leibacher

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Author name code: leibacher
ADS astronomy entries on 2022-09-14
author:"Leibacher, John W."

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Title: Editorial Appreciation
Authors: Arregui, Iñigo; Leibacher, John; Mandrini, Cristina H.;
van Driel-Gesztelyi, Lidia; Wheatland, Michael S.
2022SoPh..297...11A Altcode:
No abstract at ADS

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Title: A journey of exploration to the polar regions of a star:
probing the solar poles and the heliosphere from high helio-latitude
Authors: Harra, Louise; Andretta, Vincenzo; Appourchaux, Thierry;
Baudin, Frédéric; Bellot-Rubio, Luis; Birch, Aaron C.; Boumier,
Patrick; Cameron, Robert H.; Carlsson, Matts; Corbard, Thierry;
Davies, Jackie; Fazakerley, Andrew; Fineschi, Silvano; Finsterle,
Wolfgang; Gizon, Laurent; Harrison, Richard; Hassler, Donald M.;
Leibacher, John; Liewer, Paulett; Macdonald, Malcolm; Maksimovic,
Milan; Murphy, Neil; Naletto, Giampiero; Nigro, Giuseppina; Owen,
Christopher; Martínez-Pillet, Valentín; Rochus, Pierre; Romoli,
Marco; Sekii, Takashi; Spadaro, Daniele; Veronig, Astrid; Schmutz, W.
2021ExA...tmp...93H Altcode: 2021arXiv210410876H
A mission to view the solar poles from high helio-latitudes (above 60°)
will build on the experience of Solar Orbiter as well as a long heritage
of successful solar missions and instrumentation (e.g. SOHO Domingo et
al. (Solar Phys. 162(1-2), 1-37 1995), STEREO Howard et al. (Space
Sci. Rev. 136(1-4), 67-115 2008), Hinode Kosugi et al. (Solar
Phys. 243(1), 3-17 2007), Pesnell et al. Solar Phys. 275(1-2),
3-15 2012), but will focus for the first time on the solar poles,
enabling scientific investigations that cannot be done by any other
mission. One of the major mysteries of the Sun is the solar cycle. The
activity cycle of the Sun drives the structure and behaviour of the
heliosphere and of course, the driver of space weather. In addition,
solar activity and variability provides fluctuating input into the
Earth climate models, and these same physical processes are applicable
to stellar systems hosting exoplanets. One of the main obstructions
to understanding the solar cycle, and hence all solar activity,
is our current lack of understanding of the polar regions. In this
White Paper, submitted to the European Space Agency in response to the
Voyage 2050 call, we describe a mission concept that aims to address
this fundamental issue. In parallel, we recognise that viewing the Sun
from above the polar regions enables further scientific advantages,
beyond those related to the solar cycle, such as unique and powerful
studies of coronal mass ejection processes, from a global perspective,
and studies of coronal structure and activity in polar regions. Not
only will these provide important scientific advances for fundamental
stellar physics research, they will feed into our understanding of
impacts on the Earth and other planets' space environment.

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Title: A Journey of Exploration to the Polar Regions of a Star:
Probing the Solar Poles and the Heliosphere from High Helio-Latitude
Authors: Finsterle, W.; Harra, L.; Andretta, V.; Appourchaux, T.;
Baudin, F.; Bellot Rubio, L.; Birch, A.; Boumier, P.; Cameron, R. H.;
Carlsson, M.; Corbard, T.; Davies, J. A.; Fazakerley, A. N.; Fineschi,
S.; Gizon, L. C.; Harrison, R. A.; Hassler, D.; Leibacher, J. W.;
Liewer, P. C.; Macdonald, M.; Maksimovic, M.; Murphy, N.; Naletto, G.;
Nigro, G.; Owen, C. J.; Martinez-Pillet, V.; Rochus, P. L.; Romoli,
M.; Sekii, T.; Spadaro, D.; Veronig, A.
2020AGUFMSH0110005F Altcode:
A mission to view the solar poles from high helio-latitudes (above
60°) will build on the experience of Solar Orbiter as well as a long
heritage of successful solar missions and instrumentation (e.g. SOHO,
STEREO, Hinode, SDO), but will focus for the first time on the solar
poles, enabling scientific investigations that cannot be done by
any other mission. One of the major mysteries of the Sun is the solar
cycle. The activity cycle of the Sun drives the structure and behaviour
of the heliosphere and is, of course, the driver of space weather. In
addition, solar activity and variability provides fluctuating input
into the Earth climate models, and these same physical processes
are applicable to stellar systems hosting exoplanets. One of the
main obstructions to understanding the solar cycle, and hence all
solar activity, is our current lack of understanding of the polar
regions. We describe a mission concept that aims to address this
fundamental issue. In parallel, we recognise that viewing the Sun
from above the polar regions enables further scientific advantages,
beyond those related to the solar cycle, such as unique and powerful
studies of coronal mass ejection processes, from a global perspective,
and studies of coronal structure and activity in polar regions. Not
only will these provide important scientific advances for fundamental
stellar physics research, they will feed into our understanding of
impacts on the Earth and other planets' space environment.

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Title: Editorial Appreciation
Authors: Leibacher, John; Mandrini, Cristina H.; van Driel-Gesztelyi,
Lidia; Wheatland, Michael S.
2019SoPh..294....3L Altcode:
We are pleased to acknowledge, with sincere thanks, the following
colleagues who supported the community by reviewing articles for Solar
Physics during 2018.

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Title: Searching for g modes. I. A new calibration of the GOLF
instrument
Authors: Appourchaux, T.; Boumier, P.; Leibacher, J. W.; Corbard, T.
2018A&A...617A.108A Altcode: 2018arXiv180700998A
Context. The recent claims of g-mode detection have restarted the
search for these potentially extremely important modes. These claims
can be reassessed in view of the different data sets available from
the SoHO instruments and ground-based instruments. Aims: We
produce a new calibration of the GOLF data with a more consistent
p-mode amplitude and a more consistent time shift correction compared
to the time series used in the past. Methods: The calibration
of 22 yr of GOLF data is done with a simpler approach that uses
only the predictive radial velocity of the SoHO spacecraft as a
reference. Using p modes, we measure and correct the time shift between
ground- and space-based instruments and the GOLF instrument. 
Results: The p-mode velocity calibration is now consistent to within
a few percent with other instruments. The remaining time shifts are
within ±5 s for 99.8% of the time series. The new calibrated
series (FITS) are available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/617/A108">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/617/A108</A>

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Title: VizieR Online Data Catalog: Sun velocities from GOLF instrument
(Appourchaux+, 2018)
Authors: Appourchaux, T.; Boumier, P.; Leibacher, J. W.; Corbard, T.
2018yCat..36170108A Altcode:
Three time series as FITS file comprising 34797600 data points of GOLF
velocity in m/s sampled at 20 sec (no time provided). The time series
starts on April 11, 1996 0:00 UT and ends on April 10, 2018 23:59:40
UT. The time series are provided for the photomultipliers PM1 and PM2,
and their arithmetic average. (2 data files).

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Title: Editorial: Last Print Issue of Solar Physics
Authors: Leibacher, John; Mandrini, Cristina H.; van Driel-Gesztelyi,
Lidia; Wheatland, Michael S.
2017SoPh..292..196L Altcode:
No abstract at ADS

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Title: Editorial Appreciation
Authors: Leibacher, John; Mandrini, Cristina H.; van Driel-Gesztelyi,
Lidia; Wheatland, Michael S.
2017SoPh..292...19L Altcode:
We are pleased to acknowledge, with sincere thanks, the following
referees who supported the community by refereeing articles for Solar
Physics during 2016.

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Title: A Distant Mirror: Solar Oscillations Observed on Neptune by
the Kepler K2 Mission
Authors: Gaulme, P.; Rowe, J. F.; Bedding, T. R.; Benomar, O.;
Corsaro, E.; Davies, G. R.; Hale, S. J.; Howe, R.; Garcia, R. A.;
Huber, D.; Jiménez, A.; Mathur, S.; Mosser, B.; Appourchaux, T.;
Boumier, P.; Jackiewicz, J.; Leibacher, J.; Schmider, F. -X.; Hammel,
H. B.; Lissauer, J. J.; Marley, M. S.; Simon, A. A.; Chaplin, W. J.;
Elsworth, Y.; Guzik, J. A.; Murphy, N.; Silva Aguirre, V.
2016ApJ...833L..13G Altcode: 2016arXiv161204287G
Starting in 2014 December, Kepler K 2 observed Neptune continuously
for 49 days at a 1 minute cadence. The goals consisted of studying its
atmospheric dynamics, detecting its global acoustic oscillations, and
those of the Sun, which we report on here. We present the first indirect
detection of solar oscillations in intensity measurements. Beyond
the remarkable technical performance, it indicates how Kepler would
see a star like the Sun. The result from the global asteroseismic
approach, which consists of measuring the oscillation frequency
at maximum amplitude ν max and the mean frequency
separation between mode overtones Δν, is surprising as the ν
max measured from Neptune photometry is larger than the
accepted value. Compared to the usual reference ν max,⊙
= 3100 μHz, the asteroseismic scaling relations therefore make the
solar mass and radius appear larger by 13.8 ± 5.8% and 4.3 ± 1.9%,
respectively. The higher ν max is caused by a combination
of the value of ν max,⊙, being larger at the time
of observations than the usual reference from SOHO/VIRGO/SPM data
(3160 ± 10 μHz), and the noise level of the K 2 time series, being
10 times larger than VIRGO’s. The peak-bagging method provides
more consistent results: despite a low signal-to-noise ratio (S/N),
we model 10 overtones for degrees ℓ = 0, 1, 2. We compare the K 2
data with simultaneous SOHO/VIRGO/SPM photometry and BiSON velocity
measurements. The individual frequencies, widths, and amplitudes mostly
match those from VIRGO and BiSON within 1σ, except for the few peaks
with the lowest S/N.

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Title: Editorial: 50 Years of Solar Physics
Authors: Charbonneau, Paul; Leibacher, John; Mandrini, Cristina;
van Driel-Gesztelyi, Lidia; Wheatland, Michael S.
2016SoPh..291.3461C Altcode: 2016SoPh..tmp..189C
No abstract at ADS

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Title: Preface to Topical Issue: Recalibration of the Sunspot Number
Authors: Clette, F.; Cliver, E. W.; Lefèvre, L.; Svalgaard, L.;
Vaquero, J. M.; Leibacher, J. W.
2016SoPh..291.2479C Altcode: 2016SoPh..tmp..184C
This topical issue contains articles on the effort to recalibrate
the sunspot number (SN) that was initiated by the Sunspot Number
Workshops. These workshops led to a revision of the Wolf sunspot number
(WSN) and a new construction of the group sunspot number (GSN),
both published herein. In addition, this topical issue includes
three independently proposed alternative SN time series (two Wolf
and one group), as well as articles providing historical context,
critical assessments, correlative analyses, and observational data,
both historical and modern, pertaining to the sunspot-number time
series. The ongoing effort to understand and reconcile the differences
between the various new sunspot number series is briefly discussed.

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Title: Are Resonant Helioseimic Modes Excited by Solar Flares?
Authors: Leibacher, John W.; Baudin, Frédéric; Rabello Soares,
Maria Cristina
2016SPD....47.0710L Altcode:
We critically examine reports that flares have been observed to
excite resonant p-modes by:-looking in detail at the results of
the ring-diagram analysis in terms of duty cycle and center-to-limb
variation of ring-diagram power.-applying the same analysis to the
Halloween flare using GONG and MDI data.-assessing the stability in
terms of oscillation power of both instruments.

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Title: Editorial Appreciation
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2016SoPh..291..337L Altcode: 2016SoPh..tmp...10L
No abstract at ADS

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Title: Preface: Probing the Sun Inside and Out
Authors: Harra, Louise; Baker, Deborah; Howe, Rachel; Leibacher,
John; van Driel-Gesztelyi, Lidia
2015SoPh..290.3091H Altcode: 2015SoPh..tmp..167H
No abstract at ADS

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Title: Preface: Radio Heliophysics: Science and Forecasting
Authors: Bisi, Mario M.; Americo Gonzalez-Esparza, J.; Jackson,
Bernard V.; Tokumaru, Munetoshi; Leibacher, John
2015SoPh..290.2393B Altcode: 2015SoPh..tmp..143B
No abstract at ADS

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Title: Excitation of Resonant Helioseimic Modes by Solar Flares.
Authors: Leibacher, John W.; Baudin, Frédéric; Rabello Soares,,
Maria Cristina
2015IAUGA..2257140L Altcode:
Flares are known to excite propagating sound waves in the solar
atmosphere, and Maurya et al. (2009), using a local analysis (ring
diagrams) of the 2003 Halloween flare, showed that they excite resonant
p-modes as well. We confirm and extend here these results by:-applying
the same analysis to other locations on the Sun at the time of the
Halloween flare-analyzing other events also showing a signature of
p-mode excitation-looking in detail at the results of the ring diagrams
analysis in terms of noise fitting and the center-to-limb variation
of ring-diagram power.

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Title: Excitation of Resonant Helioseimic Modes by Solar Flares
Authors: Leibacher, John William; Baudin, Frédéric; Rabello Soares,
Maria Cristina
2015TESS....110302L Altcode:
Flares are known to excite propagating sound waves in the solar
atmosphere, and Maurya et al. (2009), using a local analysis (ring
diagrams) of the 2003 Halloween flare, showed that they excite resonant
p-modes as well. We confirm and extend here these results by: applying
the same analysis to other locations on the Sun at the time of the
Halloween flare, analyzing other events also showing a signature
of p-mode excitation, looking in detail at the results of the ring
diagrams analysis in terms of noise fitting and the center-to-limb
variation of ring-diagram power.

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Title: Editorial Appreciation
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2015SoPh..290..657L Altcode: 2015SoPh..tmp...24L
No abstract at ADS

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Title: Helioseismic Ring-diagram Diagnostics of Solar Fares.
Authors: Leibacher, John W.; Baudin, Frédéric
2014AAS...22421817L Altcode:
Flares are known to excite waves in the solar atmosphere. Maurya et
al. (2009), using a local analysis (ring diagrams) of the 2003 Halloween
flare, also showed they excite p-modes. We confirm and extend here
these results by:-applying the same analysis to other locations on the
Sun at the time of the Halloween flare-analyzing another event also
showing a signature of p-mode excitation-looking in details at the
results of the ring diagrams analysis in terms of noise fitting.The
Halloween flare present an apparent localized excitation of p-modes,
similar to what is observed for the other event analyzed.

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Title: Editorial Appreciation
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2014SoPh..289.1455L Altcode: 2014SoPh..tmp....6L
No abstract at ADS

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Title: Solar Origins of Space Weather and Space Climate: Preface
Authors: González Hernández, I.; Komm, R.; Pevtsov, A.; Leibacher,
J. W.
2014SoPh..289..437G Altcode:
No abstract at ADS

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Title: Fifty Years of Seismology of the Sun and Stars
Authors: Jain, K.; Tripathy, S. C.; Hill, F.; Leibacher, J. W.;
Pevtsov, A. A.
2013ASPC..478.....J Altcode:
No abstract at ADS

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Title: Preface
Authors: Tomczyk, Steven; Zhang, Jie; Bastian, Timothy; Leibacher,
John W.
2013SoPh..288..463T Altcode:
No abstract at ADS

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Title: Preface
Authors: Mansour, Nagi N.; Kosovichev, Alexander G.; Komm, Rudolf;
Longcope, Dana; Leibacher, John W.
2013SoPh..287....1M Altcode:
No abstract at ADS

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Title: Preface
Authors: Berghmans, D.; De Groof, A.; Dominique, M.; Hochedez, J. -F.;
Leibacher, J. W.
2013SoPh..286....1B Altcode:
No abstract at ADS

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Title: Preface
Authors: Ireland, J.; Young, C. A.; Leibacher, J. W.
2013SoPh..283....3I Altcode:
No abstract at ADS

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Title: Preface
Authors: Fleck, Bernhard; Heber, Bernd; Vourlidas, Angelos; van
Driel-Gesztelyi, Lidia; Mandrini, Cristina H.; Leibacher, John
2012SoPh..281....1F Altcode: 2012SoPh..tmp..223F
No abstract at ADS

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Title: Preface
Authors: Nakariakov, V. M.; Georgoulis, M. K.; Poedts, S.; van
Driel-Gesztelyi, L.; Mandrini, C. H.; Leibacher, J.
2012SoPh..280..295N Altcode: 2012SoPh..tmp..226N
No abstract at ADS

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Title: Extracting Low-Degree Timeseries and Modes from Imaged
Helioseismology
Authors: Leibacher, John W.
2012AAS...22020502L Altcode:
Results from a new approach to obtaining helioseismic mode time series
will be presented.

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Title: Preface
Authors: Fan, Yuhong; Fisher, George; Leibacher, John
2012SoPh..277....1F Altcode: 2011SoPh..tmp..423F
No abstract at ADS

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Title: The Sun-Earth Connection near Solar Minimum: Placing it
into Context
Authors: Bisi, Mario M.; Thompson, Barbara J.; Emery, Barbara A.;
Gibson, Sarah E.; Leibacher, John; van Driel-Gesztelyi, Lidia
2011SoPh..274....1B Altcode:
No abstract at ADS

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Title: Helioseismic Observations of Solar Convection Zone Dynamics
Authors: Hill, Frank; Howe, Rachel; Komm, Rudi; Hernández, Irene
González; Kholikov, Shukur; Leibacher, John
2011IAUS..271...15H Altcode:
The large-scale dynamics of the solar convection zone have been inferred
using both global and local helioseismology applied to data from the
Global Oscillation Network Group (GONG) and the Michelson Doppler
Imager (MDI) on board SOHO. The global analysis has revealed temporal
variations of the “torsional oscillation” zonal flow as a function of
depth, which may be related to the properties of the solar cycle. The
horizontal flow field as a function of heliographic position and depth
can be derived from ring diagrams, and shows near-surface meridional
flows that change over the activity cycle. Time-distance techniques
can be used to infer the deep meridional flow, which is important for
flux-transport dynamo models. Temporal variations of the vorticity can
be used to investigate the production of flare activity. This paper
summarizes the state of our knowledge in these areas.

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Title: Deep Meridional Flow Measurements from GONG: Temporal and
Depth Variations
Authors: Kholikov, Shukur; Leibacher, J.; Hill, F.
2011SPD....42.1618K Altcode: 2011BAAS..43S.1618K
We present measurements of meridional flow using time-distance analysis
of GONG data. To push the depth profile of the flow deeper, we average
time-difference measurements over 15 years. In order to increase the
signal-to-noise ratio, and to reduce contamination from other modes,
we utilized both phase velocity and low-m filtering. This approach
seems to be capable of extending the meridional-flow measurements
down to 0.7 Rsun. Our preliminary results indicate that the precision
achieved is very close to that required to measure the reverse flow
down to the base of the solar convection zone where it is expected to be
situated. Typical uncertainties for most depths within mid-latitudes are
less than 0.02 seconds. At high latitudes, due to projection effects,
error bars increase up to 0.06 seconds. There is a significant change in
the nature of the time differences at the bottom of the convection zone.

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Title: AIA Observations of Sunspot Waves
Authors: Leibacher, John W.; Soubrié, E.; Auchère, F.; Baudin, F.
2011SPD....42.2115L Altcode: 2011BAAS..43S.2115L
Waves in the low solar atmosphere above sunspots i) present an
interesting phenomenon in their own right, ii) are potentially a probe
of magnetic structures (e.g. "plumes") in the sunspot atmosphere and a
source of excitation of higher, coronal loop waves, and iii) are coupled
to umbral flashes and sub-surface, helioseismic waves in a manner that
is not fully understood. We present an analysis of AIA observations
of waves in AR 11092, showing their propagation, temporal coherence,
and angular symmetry; characterizing them in terms of frequency,
amplitude, and propagation speed.

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Title: Helioseismic Studies With Multi-wavelength Data From HMI And
AIA Onboard SDO
Authors: Hill, Frank; Jain, K.; Tripathy, S.; Kholikov, S.; Gonzalez
Hernandez, I.; Leibacher, J.; Howe, R.; Baudin, F.; Carlsson, M.;
Chaplin, W.; Tarbell, T.
2011SPD....42.2111H Altcode: 2011BAAS..43S.2111H
The successful launch of the Solar Dynamics Observatory (SDO) in
February 2010 opens important, new possibilities for helioseismic
exploration of the solar interior and atmosphere using multi-wavelength
observations from multiple instruments. In order to better understand
the solar interior and atmosphere, as well as the physics of the
helioseismic modes and waves themselves, we exploit the potential of
the Atmospheric Imaging Assembly (AIA) 1600 and 1700 Angstrom continuum
measurements and the contemporaneous Helioseismic and Magnetic Imager
(HMI) Fe I 6173.3 Angstrom velocity and intensity observations. Standard
techniques of helioseismology e.g Sun-as-a-star, spherical harmonic
analysis, ring diagrams, and time- distance analysis are applied to
obtain acoustic mode parameters and other characteristics. Here we
present our preliminary results, and interpret these in the context
of the differences in the heights of formation of the lines.

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Title: The extreme physical properties of the CoRoT-7b super-Earth
Authors: Léger, A.; Grasset, O.; Fegley, B.; Codron, F.; Albarede,
A. F.; Barge, P.; Barnes, R.; Cance, P.; Carpy, S.; Catalano, F.;
Cavarroc, C.; Demangeon, O.; Ferraz-Mello, S.; Gabor, P.; Grießmeier,
J. -M.; Leibacher, J.; Libourel, G.; Maurin, A. -S.; Raymond, S. N.;
Rouan, D.; Samuel, B.; Schaefer, L.; Schneider, J.; Schuller, P. A.;
Selsis, F.; Sotin, C.
2011Icar..213....1L Altcode: 2011arXiv1102.1629L
The search for rocky exoplanets plays an important role in our quest for
extra-terrestrial life. Here, we discuss the extreme physical properties
possible for the first characterised rocky super-Earth, CoRoT-7b (
R pl = 1.58 ± 0.10 R Earth, M pl
= 6.9 ± 1.2 M Earth). It is extremely close to its star
( a = 0.0171 AU = 4.48 R st), with its spin and orbital
rotation likely synchronised. The comparison of its location in the
( M pl, R pl) plane with the predictions of
planetary models for different compositions points to an Earth-like
composition, even if the error bars of the measured quantities and the
partial degeneracy of the models prevent a definitive conclusion. The
proximity to its star provides an additional constraint on the model. It
implies a high extreme-UV flux and particle wind, and the corresponding
efficient erosion of the planetary atmosphere especially for volatile
species including water. Consequently, we make the working hypothesis
that the planet is rocky with no volatiles in its atmosphere, and derive
the physical properties that result. As a consequence, the atmosphere
is made of rocky vapours with a very low pressure ( P ⩽ 1.5 Pa),
no cloud can be sustained, and no thermalisation of the planet is
expected. The dayside is very hot (2474 ± 71 K at the sub-stellar
point) while the nightside is very cold (50-75 K). The sub-stellar
point is as hot as the tungsten filament of an incandescent bulb,
resulting in the melting and distillation of silicate rocks and the
formation of a lava ocean. These possible features of CoRoT-7b could be
common to many small and hot planets, including the recently discovered
Kepler-10b. They define a new class of objects that we propose to name
" Lava-ocean planets".

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Title: Editorial Appreciation
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2011SoPh..269....1L Altcode: 2011SoPh..tmp...21L
No abstract at ADS

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Title: Meridional-Flow Measurements from 15 Years of GONG
Spherical-Harmonic Time Series
Authors: Kholikov, S.; González Hernández, I.; Hill, F.; Leibacher,
J.
2011JPhCS.271a2052K Altcode:
We present results of meridional-flow measurements for 1995-2009, using
travel-time differences from velocity images reconstructed using GONG
spherical harmonic (SH) coefficients after applying phase-velocity and
low-m filters. This filtering technique increases the signal-to-noise
ratio and thus extends travel-time measurements to relatively high
latitudes and deep into the convection zone. Preliminary analyses shows
a strong one-year periodicity presumably due to solar pole misalignment
and B0-angle artifacts, which makes it difficult to see
underlying temporal variations. Removing a simple one-year-period sine
wave fit reveals long-term temporal variations of the flow on top
of this yearly periodicity. High-latitude measurements are affected
more stronger by foreshortening and B0 -angle artifacts. We
analyze different B0-angle intervals separately, so in each
hemisphere better high-latitude visibility comes six months apart. This
approach suggests why at high latitudes travel-time measurements of
meridional flow shows a tendency to change sign instead of continuing
towards the poles.

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Title: Angular-degree dependence of p-mode frequencies during solar
cycle 23
Authors: Tripathy, S. C.; Jain, K.; Salabert, D.; Garcia, R. A.;
Hill, F.; Leibacher, J. W.
2011JPhCS.271a2055T Altcode:
We analyze simultaneous helioseismic observations collected by the
ground- and space-based instruments during solar cycle 23 by computing
oscillation frequencies for low- and intermediate-degree p-modes on a
time scale of 36 days. We find that the frequency shifts corresponding
to different angular degree, ell, indicate different epochs for the
onset of the solar cycle 24. The analysis also indicates the presence
of double minima between cycles 23 and 24 for some range of ell values.

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Title: The Future of IHY Campaigns: Transition to the International
Space Weather Initiative
Authors: Raulin, Jean-Pierre; Davila, Joseph M.; Bogdan, Thomas;
Yumoto, Kiyohumi; Leibacher, John
2010HiA....15..501R Altcode:
We will present the relevant activities performed during the
International Heliophysical Year (IHY) program during the 5 year
period 2004 - 2008. The IHY was a major international effort that
involved the deployment of new instrumentation, new observations from
the ground and in space, and a strong education component. Under the
United Nations Office for Outer Space program called Basic Space
Science Initiative (UNBSSI), instrument arrays have been deployed
to provide global measurements of heliophysical phenomena. As
a result, significant scientific and educational collaborations
emerged between the organizing groups and the host country teams. In
view of the great successes achieved by the IHY during these years,
we propose to continue the highly successful collaboration with the
UN program to study the universal processes in the solar system
that affect the interplanetary and terrestrial environments, and
to continue to coordinate the deployment and operation of new and
existing instrumentation arrays aimed at understanding the impacts of
Space Weather on Earth and the near-Earth environment. To this end,
we propose a new program, the International Space Weather Initiative
(ISWI). The ISWI strongly complements the International Living With a
Star (ILWS) program, providing more attention nationally, regionally,
and internationally for the ILWS program. Based on a three-year program
activity, the ISWI would provide the opportunity for scientists around
the world to participate in this exciting quest to understand the
effect of space disturbances on our Earth environment.

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Title: Using helioseismology to understand and predict the solar cycle
Authors: Hill, Frank; Komm, Rudi; Howe, Rachel; Gonzalez Hernandez,
Irene; Kholikov, Shukur; Leibacher, John
2010shin.confE.156H Altcode:
Helioseismology is now being used to investigate the subsurface
flows that are related to the solar cycle. The relevant flows are the
east-west zonal flows (torsional oscillation), and the north-south
meridional flows. This poster will summarize the relationship of the
timing of the solar cycle with the characteristics of the zonal and
meridional flows; as well as what we know about the nature of the deep
meridional flows that play a role in the dynamo.

---------------------------------------------------------
Title: What Solar Oscillation Tell Us About the Solar Minimum
Authors: Jain, K.; Tripathy, S. C.; Burtseva, O.; H´Ndez, I. G.;
Hill, F.; Howe, R.; Kholikov, S.; Komm, R.; Leibacher, J.
2010ASPC..428...57J Altcode: 2010arXiv1002.2411J
The availability of continuous helioseismic data for two consecutive
solar minima has provided a unique opportunity to study the changes
in the solar interior that might have led to this unusual minimum. We
present preliminary analysis of intermediate-degree mode frequencies in
the 3 mHz band during the current period of minimal solar activity and
show that the mode frequencies are significantly lower than those during
the previous activity minimum. Our analysis does not show any signature
of the beginning of cycle 24 until the end of 2008. In addition, the
zonal and meridional flow patterns inferred from inverting frequencies
also hint at a delayed onset of a new cycle. The estimates of travel
time are higher than the previous minimum confirming a relatively weak
solar activity during the current minimum.

---------------------------------------------------------
Title: Meridional Flow Measurements from 15 Years of GONG Spherical
Harmonic Time Series
Authors: Leibacher, John W.; Kholikov, S.; Hill, F.
2010AAS...21640003L Altcode: 2010BAAS...41..855L
We present the results of a meridional flow time-distance analysis
based on GONG data. In order to increase the signal-to-noise ratio,
and to reduce contamination from other modes, we utilize a low-m
filtering technique, which seems capable of extending the meridional
flow measurements down to the deep layers of the convection zone
(0.7R°). Our preliminary results indicate that the precision
achieved is very close to that required to measure the reverse flow
down to the base of the solar convection zone where it is expected to
be situated. To avoid projection effects at high latitudes, and to
extend the analysis to higher latitudes, we analyze extreme B-angle
time periods separately. We discuss the significance of temporal
variations of meridional flow in the presence of additional flows
around active regions.

---------------------------------------------------------
Title: Solar Observation Target Identification Convention for use
in Solar Physics
Authors: Leibacher, John; Sakurai, Takashi; Schrijver, Carolus J.;
van Driel-Gesztelyi, Lidia
2010SoPh..263....1L Altcode: 2010SoPh..263....1.; 2010SoPh..tmp...71.
We strongly encourage the use of a standardized target identification
to be included in pub- lications on solar events. The primary purpose
is to enable the automated identification of publications on the same
event, or on other related events, in the on-line literature by search
engines such as the Astrophysics Data System (ADS). The convention does
not aim to categorize or classify events, but is limited specifically
to the identification of regions in space and intervals in time within
which events occur.

---------------------------------------------------------
Title: Preface
Authors: Ireland, J.; Young, C. A.; Leibacher, J.
2010SoPh..262..233I Altcode: 2010SoPh..tmp...46I; 2010SoPh..tmp...58I
No abstract at ADS

---------------------------------------------------------
Title: Editorial Appreciation
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2010SoPh..262....1L Altcode: 2010SoPh..tmp...18L
No abstract at ADS

---------------------------------------------------------
Title: Unusual Trends in Solar P-Mode Frequencies During the Current
Extended Minimum
Authors: Tripathy, S. C.; Jain, K.; Hill, F.; Leibacher, J. W.
2010ApJ...711L..84T Altcode: 2010arXiv1002.1690T
We investigate the behavior of the intermediate-degree mode frequencies
of the Sun during the current extended minimum phase to explore the
time-varying conditions in the solar interior. Using contemporaneous
helioseismic data from the Global Oscillation Network Group (GONG) and
the Michelson Doppler Imager (MDI), we find that the changes in resonant
mode frequencies during the activity minimum period are significantly
greater than the changes in solar activity as measured by different
proxies. We detect a seismic minimum in MDI p-mode frequency shifts
during 2008 July-August but no such signature is seen in mean shifts
computed from GONG frequencies. We also analyze the frequencies of
individual oscillation modes from GONG data as a function of latitude
and observe a signature of the onset of the solar cycle 24 in early
2009. Thus, the intermediate-degree modes do not confirm the onset
of the cycle 24 during late 2007 as reported from the analysis of the
low-degree Global Oscillations at Low Frequency frequencies. Further,
both the GONG and MDI frequencies show a surprising anti-correlation
between frequencies and activity proxies during the current minimum,
in contrast to the behavior during the minimum between cycles 22 and 23.

---------------------------------------------------------
Title: Variation of Oscillation Mode Parameters over Solar Cycle 23:
An Analysis on Different Time Scales
Authors: Tripathy, S. C.; Hill, F.; Jain, K.; Leibacher, J. W.
2009ASPC..416..285T Altcode: 2009arXiv0903.2074T
We investigate the variation in the mode parameters obtained from time
series of length nine, 36, 72 and 108 days to understand the changes
occurring on different time-scales. The regression analysis between
frequency shifts and activity proxies indicates that the correlation
and slopes are correlated and both increase in going from time series
of nine to 108 days. We also observe that the energy of the mode is
anti-correlated with solar activity while the rate at which the energy
is supplied remains constant over the solar cycle.

---------------------------------------------------------
Title: Solar Physics Publication Ethics Policies
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2009SoPh..260....1L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Helioseismic Spectral Diagnostics - An Update
Authors: Leibacher, John W.; Baudin, F.; Belkacem, K.; Dupret, M.;
Goupil, M.; Gouttebroze, P.; Samadi, R.
2009SPD....40.0716L Altcode:
In order to test models of the excitation of p modes and their behavior
in the visible atmosphere, we calculate time sequences of Fraunhofer
absorption line profiles of the Ni, Fe, K, Na, and Ca lines used in
helioseismology, focusing on Sun-as-a-star observations in this initial
work. The atmospheric models, which give rise to the line profiles, are
based on the VAL-C, perturbed by realistic p-mode eigenfunctions. The
time sequences of line profiles are analyzed as for various instruments,
to compare predicted and observed mode amplitudes as a function of
temporal frequency

---------------------------------------------------------
Title: Measurement of Low Signal-To-Noise Ratio Solar p-Modes in
Spatially Resolved Helioseismic Data
Authors: Salabert, D.; Leibacher, J.; Appourchaux, T.; Hill, F.
2009ApJ...696..653S Altcode: 2009arXiv0902.2561S
We present an adaptation of the rotation-corrected, m-averaged
spectrum technique designed to observe low signal-to-noise ratio
(S/N), low-frequency solar p-modes. The frequency shift of each
of the 2l + 1 m spectra of a given (n, l) multiplet is chosen that
maximizes the likelihood of the m-averaged spectrum. A high S/N can
result from combining individual low S/N, individual-m spectra, none
of which would yield a strong enough peak to measure. We apply the
technique to Global Oscillation Network Group and Michelson Doppler
Imager data and show that it allows us to measure modes with lower
frequencies than those obtained with classic peak-fitting analysis
of the individual-m spectra. We measure their central frequencies,
splittings, asymmetries, lifetimes, and amplitudes. The low frequency,
low- and intermediate-angular degrees rendered accessible by this
new method correspond to modes that are sensitive to the deep solar
interior down to the core (l &lt;= 3) and to the radiative interior
(4 &lt;= l &lt;= 35). Moreover, the low-frequency modes have deeper
upper turning points, and are thus less sensitive to the turbulence and
magnetic fields of the outer layers, as well as uncertainties in the
nature of the external boundary condition. As a result of their longer
lifetimes (narrower linewidths) at the same S/N the determination of
the frequencies of lower frequency modes is more accurate, and the
resulting inversions should be more precise.

---------------------------------------------------------
Title: Editorial Appreciation
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2009SoPh..255....1L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: POLAR investigation of the Sun—POLARIS
Authors: Appourchaux, T.; Liewer, P.; Watt, M.; Alexander, D.;
Andretta, V.; Auchère, F.; D'Arrigo, P.; Ayon, J.; Corbard, T.;
Fineschi, S.; Finsterle, W.; Floyd, L.; Garbe, G.; Gizon, L.; Hassler,
D.; Harra, L.; Kosovichev, A.; Leibacher, J.; Leipold, M.; Murphy,
N.; Maksimovic, M.; Martinez-Pillet, V.; Matthews, B. S. A.; Mewaldt,
R.; Moses, D.; Newmark, J.; Régnier, S.; Schmutz, W.; Socker, D.;
Spadaro, D.; Stuttard, M.; Trosseille, C.; Ulrich, R.; Velli, M.;
Vourlidas, A.; Wimmer-Schweingruber, C. R.; Zurbuchen, T.
2009ExA....23.1079A Altcode: 2008ExA...tmp...40A; 2008arXiv0805.4389A
The POLAR Investigation of the Sun (POLARIS) mission uses a combination
of a gravity assist and solar sail propulsion to place a spacecraft
in a 0.48 AU circular orbit around the Sun with an inclination of 75°
with respect to solar equator. This challenging orbit is made possible
by the challenging development of solar sail propulsion. This first
extended view of the high-latitude regions of the Sun will enable
crucial observations not possible from the ecliptic viewpoint or from
Solar Orbiter. While Solar Orbiter would give the first glimpse of
the high latitude magnetic field and flows to probe the solar dynamo,
it does not have sufficient viewing of the polar regions to achieve
POLARIS’s primary objective: determining the relation between the
magnetism and dynamics of the Sun’s polar regions and the solar cycle.

---------------------------------------------------------
Title: solarFLAG hare and hounds: estimation of p-mode frequencies
from Sun-as-star helioseismology data
Authors: Jiménez-Reyes, S. J.; Chaplin, W. J.; García, R. A.;
Appourchaux, T.; Baudin, F.; Boumier, P.; Elsworth, Y.; Fletcher,
S. T.; Lazrek, M.; Leibacher, J. W.; Lochard, J.; New, R.; Régulo,
C.; Salabert, D.; Toutain, T.; Verner, G. A.; Wachter, R.
2008MNRAS.389.1780J Altcode: 2008arXiv0807.0989J; 2008MNRAS.tmp..954J; 2008MNRAS.tmp.1026J
We report on the results of the latest solarFLAG hare-and-hounds
exercise, which was concerned with testing methods for extraction
of frequencies of low-degree solar p modes from data collected
by Sun-as-a-star observations. We have used the new solarFLAG
simulator, which includes the effects of correlated mode excitation and
correlations with background noise, to make artificial time-series data
that mimic Doppler velocity observations of the Sun-as-a-star. The
correlations give rise to asymmetry of mode peaks in the frequency
power spectrum. 10 members of the group (the hounds) applied their
`peak-bagging' codes to a 3456-d data set, and the estimated
mode frequencies were returned to the hare (who was WJC) for
comparison. Analysis of the results reveals a systematic bias in the
estimated frequencies of modes above ~1.8mHz. The bias is negative,
meaning the estimated frequencies systematically underestimate the
input frequencies. We identify two sources that are the dominant
contributions to the frequency bias. Both sources involve failure to
model accurately subtle aspects of the observed power spectral density
in the part (window) of the frequency power spectrum that is being
fitted. One source of bias arises from a failure to account for the
power spectral density coming from all those modes whose frequencies lie
outside the fitting windows. The other source arises from a failure to
account for the power spectral density of the weak l = 4 and 5 modes,
which are often ignored in Sun-as-a-star analysis. The Sun-as-a-star
peak-bagging codes need to allow for both sources, otherwise the
frequencies are likely to be biased.

---------------------------------------------------------
Title: AsteroFLAG — from the Sun to the stars
Authors: Chaplin, W. J.; Appourchaux, T.; Arentoft, T.; Ballot, J.;
Baudin, F.; Bazot, M.; Bedding, T. R.; Christensen-Dalsgaard, J.;
Creevey, O. L.; Duez, V.; Elsworth, Y.; Fletcher, S. T.; García,
R. A.; Gough, D. O.; Jiménez, A.; Jiménez-Reyes, S. J.; Houdek, G.;
Kjeldsen, H.; Lazrek, M.; Leibacher, J. W.; Monteiro, M. J. P. F. G.;
Neiner, C.; New, R.; Régulo, C.; Salabert, D.; Samadi, R.; Sekii,
T.; Sousa, S. G.; Toutain, T.; Turck-Chièze, S.
2008JPhCS.118a2048C Altcode:
We stand on the threshold of a critical expansion of asteroseismology
of Sun-like stars, the study of stellar interiors by observation
and analysis of their global acoustic modes of oscillation. The
Sun-like oscillations give a very rich spectrum allowing the internal
structure and dynamics to be probed down into the stellar cores to
very high precision. Asteroseismic observations of many stars will
allow multiple-point tests of crucial aspects of stellar evolution
and dynamo theory. The aims of the asteroFLAG collaboration are to
help the community to refine existing, and to develop new, methods
for analysis of the asteroseismic data on the Sun-like oscillators.

---------------------------------------------------------
Title: Development of a new analysis technique to measure low
radial-order p modes in spatially-resolved helioseismic data
Authors: Salabert, David; Leibacher, John W.; Appourchaux, Thierry
2008JPhCS.118a2086S Altcode: 2007arXiv0711.2825S
In order to take full advantage of the long time series collected by
the GONG and MDI helioseismic projects, we present here an adaptation
of the rotation-corrected m-averaged spectrum technique in order to
observe low radial-order solar p modes. Modeled profiles of the solar
rotation demonstrated the potential advantage of such a technique
[1, 2, 3]. Here we develop a new analysis procedure which finds the
best estimates of the shift of each m of a given (n, ι) multiplet,
commonly expressed as an expansion in a set of orthogonal polynomials,
which yield the narrowest mode in the m-averaged spectrum. We apply the
technique to the GONG data for modes with 1 &lt;= ι &lt;= 25 and show
that it allows us to measure lower-frequency modes than with classic
peak-fitting analysis of the individual-m spectra.

---------------------------------------------------------
Title: Preface
Authors: Gizon, Laurent; Cally, Paul; Leibacher, John
2008SoPh..251....1G Altcode: 2008SoPh..tmp..148G
No abstract at ADS

---------------------------------------------------------
Title: Solar Interior Meridional Flows using Zonal Modes from GONG
Authors: Leibacher, J. W.; Kholikov, S.
2008AGUSMSP41A..07L Altcode:
We present two different time-distance techniques to measure
meridional-flow-induced travel-time differences. We use GONG zonal
spherical harmonic coefficients ( m = 0 ) and longitude-averaged time
series for the 1995 -- 2007 time period. Both data sets represents
isolated waves propagating only in the North -- South direction. We
demonstrate that it is possible to obtain travel-time differences with
lower turning point about 200 Mm, which correspond to the tachocline
region. We do not see any evidence of equatorward flow.

---------------------------------------------------------
Title: Low-Frequency Solar p Modes in GONG and MDI Observations
using m-Averaged Spectra
Authors: Leibacher, J.; Salabert, D.; Appourchaux, T.; Hill, F.
2008AGUSMSP41A..06L Altcode:
The GONG and MDI global helioseismology pipelines provide solar acoustic
mode parameters for 108- and 72-day time series respectively by fitting
the 2 ℓ + 1 individual-m spectra of a given (n, ℓ/) multiplet
either individually (GONG) or simultaneously (MDI). Our knowledge of
the variable solar interior through helioseismic observations derives
primarily from these two analysis pipelines. We have developed a
new method to extract the mode parameters by adjusting the rotation-
and structure-induced frequency shift for each m-spectrum to minimize
the mode width in the m-averaged spectrum. The m-averaged spectrum
appears to be a powerful tool for low signal-to-noise-ratio modes in the
low-frequency range where the modes have very long lifetimes. Indeed,
in the case of spatially-resolved helioseismic data (MDI, GONG, HMI),
for a given multiplet (n, ℓ/), there exist 2 ℓ + 1 individual-m
spectra, which can result in an average spectrum with a SNR ≫ 1 even
when the individual-m spectra have a SNR &lt; 1. We show here that
the m-averaged spectrum technique, applied to the GONG 108-day and MDI
72-day time series, gives us access to a whole new range of predicted,
low-SNR modes that had not been successfully fitted by the current
MDI and GONG peak-fitting pipelines. We show that the modes that are
measured by both techniques are extracted without bias. We apply this
technique to 360-, 720-, 1080-, and 1440-day long GONG time series to
infer the variability of the mode parameters with solar activity in
the low-frequency range below ~ 1500 μHz.

---------------------------------------------------------
Title: Searching for p-modes in MOST Procyon data: another view
Authors: Baudin, F.; Appourchaux, T.; Boumier, P.; Kuschnig, R.;
Leibacher, J. W.; Matthews, J. M.
2008A&A...478..461B Altcode: 2007arXiv0711.0601B
Context: Photometry of Procyon obtained by the MOST satellite in
2004 has been searched for p modes by several groups, with sometimes
contradictory interpretations. Aims: We explore two possible
factors that complicate the analysis and may lead to erroneous reports
of p modes in these data. Methods: Two methods are used to
illustrate the role of subtle instrumental effects in the photometry:
time-frequency analysis, and a search for regularly spaced peaks in a
Fourier spectrum based on the echelle diagramme approach. Results:
We find no convincing evidence of a p-mode signal in the MOST Procyon
data. We can account for an apparent excess of power close to the p-mode
frequency range and signs of structure in an echelle diagramme in terms
of instrumental effects. Based on data from the MOST satellite,
a Canadian Space Agency mission, jointly operated by Dynacon Inc., the
University of Toronto Institute for Aerospace Studies and the University
of British Columbia, with the assistance of the University of Vienna.

---------------------------------------------------------
Title: Preface: A Topical Issue in Honor of Professor Bernard Roberts
Authors: Ballester, J. L.; Erdélyi, R.; Hood, A. W.; Leibacher,
J. W.; Nakariakov, V. M.
2007SoPh..246....1B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Joint Discussion 17 Highlights of recent progress in the
seismology of the Sun and Sun-like stars
Authors: Bedding, Timothy R.; Brun, Allan S.; Christensen-Dalsgaard,
Jørgen; Crouch, Ashley; De Cat, Peter; García, Raphael A.; Gizon,
Laurent; Hill, Frank; Kjeldsen, Hans; Leibacher, John W.; Maillard,
Jean-Pierre; Mathis, S.; Rabello-Soares, M. Cristina; Rozelot,
Jean-Pierre; Rempel, Matthias; Roxburgh, Ian W.; Samadi, Réza; Talon,
Suzanne; Thompson, Michael J.
2007HiA....14..491B Altcode:
The seismology and physics of localized structures beneath the surface
of the Sun takes on a special significance with the completion in
2006 of a solar cycle of observations by the ground-based Global
Oscillation Network Group (GONG) and by the instruments on board the
Solar and Heliospheric Observatory (SOHO). Of course, the spatially
unresolved Birmingham Solar Oscillation Network (BiSON) has been
observing for even longer. At the same time, the testing of models of
stellar structure moves into high gear with the extension of deep probes
from the Sun to other solar-like stars and other multi-mode pulsators,
with ever-improving observations made from the ground, the success of
the MOST satellite, and the recently launched CoRoT satellite. Here
we report the current state of the two closely related and rapidly
developing fields of helio- and asteroseimology.

---------------------------------------------------------
Title: Solar Oscillation Frequency Changes on Time Scales of Nine Days
Authors: Tripathy, S. C.; Hill, F.; Jain, K.; Leibacher, J. W.
2007SoPh..243..105T Altcode: 2006astro.ph..8348T
We establish that global solar p-mode frequencies can be measured with
sufficient precision on time scales as short as nine days to detect
activity-related shifts. Using ten years of GONG data, we report
that mode-mass and error-weighted frequency shifts derived from nine
days are significantly correlated with the strength of solar activity
and are consistent with long-duration measurements from GONG and the
SOHO/MDI instrument. The analysis of the year-wise distribution of the
frequency shifts with change in activity indices shows that both the
linear-regression slopes and the magnitude of the correlation varies
from year to year and they are well correlated with each other. The
study also indicates that the magnetic indices behave differently in the
rising and falling phases of the activity cycle. For the short-duration
nine-day observations, we report a higher sensitivity to activity.

---------------------------------------------------------
Title: Rotation Of The Deep Solar Interior From A Solar Cycle Of
Gong Data
Authors: Leibacher, John W.; Salabert, D.; Appourchaux, T.; Hill,
F.; Howe, R.
2007AAS...210.2219L Altcode: 2007BAAS...39..127L
We use 3960 days of Global Oscillation Network Group (GONG) data
to derive the rotation of the deep solar interior. We obtain the
splitting of low signal-to-noise multiplets - at low radial order
and low spherical harmonic degree - using the m-averaged spectra - a
technique that works well even when none of the individual-m spectra are
clean enough to be fit. Central frequencies and rotational splittings
are estimated down to l = 1 and 1 mHz. We illustrate here the validity
of our method and infer the radial rotation profile down to 0.2 solar
radius. This work utilizes data obtained by the Global Oscillation
Network Group (GONG) program, managed by the National Solar Observatory,
which is operated by AURA, Inc. under a cooperative agreement with
the National Science Foundation. The data were acquired by instruments
operated by the Big Bear Solar Observatory, High Altitude Observatory,
Learmonth Solar Observatory, Udaipur Solar Observatory, Instituto de
Astrofisica de Canarias, and Cerro Tololo Interamerican Observatory.

---------------------------------------------------------
Title: Recent Advances From The GONG Time-distance Helioseismology
Team
Authors: Hill, Frank; Kholikov, S.; Burtseva, O.; Leibacher, J. W.
2007AAS...210.2213H Altcode: 2007BAAS...39..126H
We present some recent work using the time-distance method of local
helioseismology as applied to Global Oscillation Network Group (GONG)
data. Four projects will be included: 1) North-south travel time
differences for zonal modes (m=0) have been computed for the period
1995-2006. These measurements provide information on the meridional
flow, and can be used to study temporal variations over the activity
cycle. 2) The autocorrelations of the low-degree (l=0, 1, 2, 3)
time series have been computed. These functions have been analyzed
to obtain a very precise measurement of the large splitting and solar
acoustic radius. A significant temporal variation correlated with the
activity level can be clearly seen. 3) The lifetimes of high-degree
modes have been estimated with the time-distance method. The results for
high and low activity will be discussed. 4) A project to search
for active regions prior to their emergence has been initiated. Some
approaches to the problem will be outlined. The National Solar
Observatory is operated by the Association of Universities for Research
in Astronomy under a cooperative agreement with the National Science
Foundation, for the benefit of the astronomical community.

---------------------------------------------------------
Title: On cross-spectrum capabilities for detecting stellar
oscillation modes
Authors: Appourchaux, T.; Leibacher, J.; Boumier, P.
2007A&A...463.1211A Altcode:
Aims:Long-lived stellar oscillation modes are usually detected using
Fourier transforms of time series of stellar radial velocities or
brightness. It is commonly thought that one could use the cross spectrum
of the two signals, or alternatively use the interleaved series of a
single signal, to considerably improve the detection level by reducing
the noise level. Methods: We use a statistical analysis of the
cross spectrum to compute its mean value and rms value, and use the
associated signal-to-noise ratio for stochastically excited modes. Results: Here, we demonstrate that the gain in the signal-to-noise
ratio can indeed be improved for modes with a shorter lifetime than
the observation time, but not those with a longer lifetime than the
observation time.

---------------------------------------------------------
Title: Some remarks on the state of helioseismology
Authors: Leibacher, J. W.
2007AN....328..368L Altcode:
I offer some very brief questions and remarks on the state of
helioseismology, specifically: i) What is the relationship between
the study of a phenomenon in its own right, its use as a tool, and
the broader phenomena to which the tool can be applied? ii) Does the
jargon of our local helioseismic techniques serve us well? iii) What
is the role of the interactions with the areas of science with which
helioseismology interacts most closely?

---------------------------------------------------------
Title: Solar MHD Theory and Observations: A High Spatial Resolution
Perspective
Authors: Leibacher, John; Stein, Robert F.; Uitenbroek, Han
2006ASPC..354.....L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Temporal variations of travel-time differences from GONG++
Authors: Kholikov, S.; Leibacher, J.
2006ESASP.624E..47K Altcode: 2006soho...18E..47K
No abstract at ADS

---------------------------------------------------------
Title: Changes to global mode parameters over a solar cycle
Authors: Tripathy, S. C.; Hill, F.; Jain, K.; Leibacher, J. W.
2006ESASP.624E..93T Altcode: 2006soho...18E..93T
No abstract at ADS

---------------------------------------------------------
Title: Future missions and activities
Authors: Leibacher, J.
2006IAUJD..17E..27L Altcode:
This overview will present the outstanding scientific questions and
the various observational programs to address them that are underway,
in development, and on the drawing boards.

---------------------------------------------------------
Title: MDI and GONG Inferences of the Changing Sun
Authors: Burtseva, O.; González Hernández, I.; Hill, F.; Howe, R.;
Jain, K.; Kholikov, S.; Komm, R.; Leibacher, J.; Toner, C.; Tripathy,
S.; Haber, D.; Hindman, B.; Ladenkov, O.; Chou, D. -Y.
2006ESASP.617E..41B Altcode: 2006soho...17E..41B
No abstract at ADS

---------------------------------------------------------
Title: Frequency Shifts on Time Scales of Nine Days
Authors: Tripathy, Sushanta C.; Hill, F.; Jain, K.; Leibacher, J. W.
2006SPD....37.0501T Altcode: 2006BAAS...38R.223T
Since the p-mode frequency changes are thought to be associated
with individual active regions that come and go continuously, one
would anticipate that the frequencies alsochange continuously on
any time scale. However, due to the finite life time of the mode,
the correlation between the frequency and activity may depend on the
length of the observing run. To test this hypothesis, we calculate and
analyze frequency variations on time scales as short as nine-days. Using
10 years of GONG data, we establish that the global p-mode frequencies
can be measured with sufficient precision on this timescale to exhibit
temporal variations. We also find that these modes are significantly
correlated with the strength of solar activity but the correlation
coefficients are smaller as compared to long-term measurements from
the GONG and SOHO/MDI.

---------------------------------------------------------
Title: Solar FLAG hare and hounds: on the extraction of rotational
p-mode splittings from seismic, Sun-as-a-star data
Authors: Chaplin, W. J.; Appourchaux, T.; Baudin, F.; Boumier, P.;
Elsworth, Y.; Fletcher, S. T.; Fossat, E.; García, R. A.; Isaak,
G. R.; Jiménez, A.; Jiménez-Reyes, S. J.; Lazrek, M.; Leibacher,
J. W.; Lochard, J.; New, R.; Pallé, P.; Régulo, C.; Salabert, D.;
Seghouani, N.; Toutain, T.; Wachter, R.
2006MNRAS.369..985C Altcode: 2006MNRAS.tmp..515C; 2006astro.ph..6748C
We report on results from the first solar Fitting at Low-Angular
degree Group (solar FLAG) hare-and-hounds exercise. The group
is concerned with the development of methods for extracting the
parameters of low-l solar p-mode data (`peak bagging'), collected by
Sun-as-a-star observations. Accurate and precise estimation of the
fundamental parameters of the p modes is a vital pre-requisite of all
subsequent studies. Nine members of the FLAG (the `hounds') fitted
an artificial 3456-d data set. The data set was made by the `hare'
(WJC) to simulate full-disc Doppler velocity observations of the
Sun. The rotational frequency splittings of the l = 1, 2 and 3 modes
were the first parameter estimates chosen for scrutiny. Significant
differences were uncovered at l = 2 and 3 between the fitted splittings
of the hounds. Evidence is presented that suggests this unwanted bias
had its origins in several effects. The most important came from the
different way in which the hounds modelled the visibility ratio of
the different rotationally split components. Our results suggest that
accurate modelling of the ratios is vital to avoid the introduction of
significant bias in the estimated splittings. This is of importance
not only for studies of the Sun, but also of the solar analogues
that will be targets for asteroseismic campaigns. Solar FLAG
URL: http://bison.ph.bham.ac.uk/~wjc/Research/FLAG.html E-mail:
wjc@bison.ph.bham.ac.uk ‡ George Isaak passed away in 2005 June
5, prior to the completion of this work. He is greatly missed by us all.

---------------------------------------------------------
Title: Editorial Appreciation
Authors: Engvold, Oddbjørn; Harvey, Jack; Leibacher, John; Sakurai,
Takashi; Švestka, Zdeněk; van Driel-Gesztelyi, Lidia; Solar Physics
editors
2006SoPh..233....1E Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Editorial
Authors: Leibacher, John; Sakurai, Takashi; van Driel-Gesztelyi, Lidia
2005SoPh..229....3L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The GONG Farside Project
Authors: Leibacher, J. W.; Braun, D.; González Hernández, I.;
Goodrich, J.; Kholikov, S.; Lindsey, C.; Malanushenko, A.; Scherrer, P.
2005AGUSMSP11B..14L Altcode:
The GONG program is currently providing near-real-time helioseismic
images of the farside of the Sun. The continuous stream of low
resolution images, obtained from the 6 earth based GONG stations, are
merged into a single data series that are the input to the farside
pipeline. In order to validate the farside images, it is crucial
to compare the results obtained from different instruments. We show
comparisons between the farside images provided by the MDI instrument
and the GONG ones. New aditions to the pipeline will allow us to create
full-hemisphere farside images, examples of the latest are shown in
this poster. Our efforts are now concentrated in calibrating the
farside signal so it became a reliable solar activity forecasting
tool. We are also testing single-skip acoustic power holography
at 5-7 mHz as a prospective means of reinforcing the signatures of
active regions crossing the the east and west limb and monitoring
acoustic emission in the neighborhoods of Sun's the poles. This work
utilizes data obtained by the Global Oscillation Network Group (GONG)
Program, managed by the National Solar Observatory, which is operated
by AURA, Inc. under a cooperative agreement with the National Science
Foundation. The data were acquired by instruments operated by the Big
Bear Solar Observatory, High Altitude Observatory, Learmonth Solar
Observatory, Udaipur Solar Observatory, Instituto de Astrofisico de
Canarias, and Cerro Tololo Interamerican Observatory, as well as
the Michaelson Doppler Imager on SoHO, a mission of international
cooperation between ESA and NASA. This work has been supported by the
NASA Living with a Star - Targeted Research and Technology program.

---------------------------------------------------------
Title: How Well do the Oscillation Frequencies Track the Activity ?
Authors: Tripathy, S. C.; Leibacher, J. W.
2005AGUSMSP13A..04T Altcode:
Variations of solar oscillation frequencies with the solar cycle at
both low and intermediate degrees are now well established. This is
manifested by an increase in frequencies of the modes from minimum to
maximum of the activity cycle. It is also known that the shifts are
strongly correlatd with different activity indices on time scales of
72 and 108 days for MDI and GONG data respectively. However, earlier
results from cycle 22 indicated that the frequencies change over
shorter periods of weeks to months. It is therefore interesting to
analyse mode frequencies and other mode parameters from time series
of shorter duration. Here, we present results from an analysis where
the frequencies are computed from 36 and 108 days long time series;
the time series being shifted by three days over a period of about 5
months. The frequencies calculated from the 36 day long time series
are much better correlated with the activity indices.

---------------------------------------------------------
Title: Parker Lecture: Local Helioseismology
Authors: Leibacher, J. W.
2005AGUSMSP23C..01L Altcode:
This brief introduction to the science of local helioseismolgy - the
study of travelling sound waves in addition to the standing waves
familiar from global helioseismology - will demonstrate how we can
now probe the temporally varying spatial inhomogeneities within the
solar interior, and illustrate this with results on meridional flows
and torsional oscillations, sunspot and active region structure,
supergranulation, images of farside of the Sun, as well as signatures
of flares.

---------------------------------------------------------
Title: GONG Travel Time Measurements of Meridional Flows for a Decade
Authors: Kholikov, S.; Leibacher, J.
2005AGUSMSP11B..04K Altcode:
We present measurements of sub-surface meridional flows derived
from the difference in travel time between northward and southward
propagating sound waves, and their variations during the period from
May 1995 to February 2004. We show that for measurements at depths
of 20 Mm or deeper, the original low spatial resolution GONG data
can be used to extend our study of temporal variations of meridional
flows back to the previous solar minimum. In addition to the usual
approach using velocity images, we demonstrate that spherical harmonic
(SH) coefficient time series for m = 0 provide an effective means
for filtering for waves that are propagating directly northward or
southward. Another advantage of using SH coefficient time series more
generally is that phase velocity filtering can be done for any l range,
without an implicit of plane-wave assumption.

---------------------------------------------------------
Title: Remarkable Low Temperature Emission of the 4 November 2003
Limb Flare
Authors: Leibacher, J. W.; Harvey, J. W.; Kopp, G.; Hudson, H.;
GONG Team
2004AAS...204.0213L Altcode: 2004BAAS...36..669L
Strong (&gt; 1.5 times normal intensity) continuum and photospheric line
emission of the 4 November 2003 X28 flare was recorded simultaneously
by three widely separated GONG instruments. Emission was seen from
on the disk to &gt; 20" above the limb for nearly one hour, likely
making this event the longest duration white light flare observed
to date. GONG observations are one-minute duration integrations of
intensity averaged across a Lyot filter bandpass of about 90 pm FWHM
centered on the Ni I line at 676.8 nm with 2.5" instrument pixel
size. Spatial resolution is limited by diffraction and seeing to
greater than 5". Additional measurements include the Doppler shift and
strength of the spectrum line. These latter measurements indicate that
continuum and line emission contributed about equally to the observed
intensity signal. Light curves and images of the flare show a notable
two-kernel disk event starting at about 19:33 UTC followed by a much
stronger event that peaked at about 19:44. Rare, white-light prominences
were visible above the limb after 19:34. Comparison of total solar
irradiance measurements from the TIM instrument on board the SORCE
spacecraft with full-disk integrated GONG intensities shows the global
five-minute oscillation and the white light flare. The latter is much
weaker in the GONG data, suggesting that most of the TIM flare signal
arises from other, most likely shorter, wavelengths. This work
utilizes data obtained by the Global Oscillation Network Group (GONG)
Program, managed by the National Solar Observatory, which is operated
by AURA, Inc. under a cooperative agreement with the National Science
Foundation. SORCE is supported by NASA NAS5-97045

---------------------------------------------------------
Title: Acoustic Holographic Studies of Solar Active Regions
Authors: Malanushenko, A.; Braun, D.; Kholikov, S.; Leibacher, J.;
Lindsey, C.
2004IAUS..223..283M Altcode: 2005IAUS..223..283M
We present results of a study of the morphology and evolution of
active regions using solar acoustic holography. These include acoustic
signatures of large far-side active regions and their relationship to
near-side activity indices a half rotation before and after the farside
image, and the direct comparison of near-side acoustic signatures with
the standard activity indicators, not only in their own right but also
to calibrate the farside acoustic signature.

---------------------------------------------------------
Title: The physics of solar and solar-like oscillations
Authors: Bedding, T. R.; Leibacher, J. W.
2004pssl.book.....B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Natural Interpolation and Consistent Extrapolation of Time
Series arising from Dense Multi-Mode Spectra
Authors: Leibacher, J. W.
2003SPD....34.0810L Altcode: 2003BAAS...35R.823L
The study of the temporal variation of phenomenon is often hampered by
the incompleteness of our observations. This is particularly disruptive
for highly periodic signals that are interrupted by periodic gaps, which
introduce sidelobes that are difficult - if not impossible - to remove
by deconvolution techniques if the spectral peaks are dense compared to
the sidelobe separation. This is the case for the study of many classes
of variable stars, including the Sun, where once per day interuptions
are the norm. However, for signals with coherence times longer than the
interuptions, there is little ambiguity as to the unobserved behaviour
of the signal - that is the frequency, phase, and amplitude of a mode
can not change significantly during a time small compared with the mode
lifetime - and the missing data can be replaced with high fidelity,
by an iterative procedure. The interpolated data is consistent with
the observed time series, and can also be used to extrapolate the time
series for times comparable with the coherence times of the constituent
modes. The method works well for spectra of unknown content, and a
priori information, e.g. the approximate frequenices of modes, can be
simply incorporated to accelerate convergence. Applications to helio-
and astereo-seismic time series will be presented.

---------------------------------------------------------
Title: The LoHCo Project. 1 -- Comparison of Ring-Diagram Local
Helioseismology on GONG++, MDI and Mt. Wilson Data Sets
Authors: Bogart, R. S.; Schou, J.; Basu, S.; Bolding, J.; Hill, F.;
Howe, R.; Komm, R. W.; Leibacher, J. W.; Toner, C. G.; Corbard, T.;
Haber, D. A.; Hindman, B. W.; Toomre, J.; Rhodes, E. J.; Rose, P. J.;
LoHCo Project Team
2003SPD....34.0804B Altcode: 2003BAAS...35..822B
Full deployment of the GONG+ enhanced observing network in October
2001 and implementation of ring-diagram helioseismology in the
GONG++ analysis pipeline this year has enabled us to make a detailed
intercomparison of results obtained through multiple paths, from
observation through each of the analysis steps. Such comparisons
can provide a certain degree of validation of the implementations
of the analysis procedures, hints of systematic errors, and better
characterization of the observations, possibly leading to improved
calibrations. The Local Helioseismology Comparison (LoHCo) Project
has been established to provide standards for intercomparison of
results obtained with different local helioseismic analysis techniques
applied to the available observational data sources. We present here
a detailed comparison of ring-diagram determinations of localized
sub-surface flows and frequency shifts obtained from both MDI and
GONG in common observing intervals during Carrington Rotation 1988
(2002/3/30 -- 2002/4/26), using both the MDI and the GONG analysis
pipelines. We also present preliminary results of similar analyses of
data obtained by the Mt. Wilson MOF during the same times. This
work is partially supported by grants from NASA and NSF.

---------------------------------------------------------
Title: Local Helioseismology and Continuous Magnetograms with GONG+
Authors: Leibacher, J.; GONG Team
2003EAEJA.....8124L Altcode:
The upgrade from the GONG classic [256x256 rectangular pixel
detectors] to the GONG+ system [ 1024x1034 square pixel detectors,
and continuous magnetograms] has been successful, and the data are
becoming available. The upgrade from the GONG Classic science products
[mode frequencies out to nominally spherical harmonic degree &lt; 180]
to the GONG+ science products [local helioseismology data products to
support "ring diagrams", "time-distance", and "helioseismic holography",
high-l global helioseismology, and continuous magnetograms] is well
underway, with the pipeline process integration underway. We present
the status of the GONG+ data, processing, and preliminary sub-surface
flow maps. NSO is sponsored by the National Science Foundation through a
cooperative agreement with the Association of Universities for Research
in Astronomy, Inc.

---------------------------------------------------------
Title: Global and Local Helioseismology with GONG+
Authors: Leibacher, John
2003IAUJD..12E..46L Altcode:
The upgrade from the GONG classic [256x256 rectangular pixel
detectors] to the GONG+ system [ 1024x1034 square pixel detectors and
continuous magnetograms] has been successful and the data are becoming
available. The upgrade from the GONG Classic science products [mode
frequencies out to nominally spherical harmonic degree &lt; 180] to the
GONG+ science products [local helioseismology data products to support
""ring diagrams"" ""time-distance"" and ""helioseismic holography""
and high-l global helioseismology] is well underway with the pipeline
process integration underway. We present the status of the GONG
Classic and GONG+ data processing as well preliminary sub-surface flow
maps. GONG is an international community based collaboration with
the NSO Big Bear Solar Observatory Mauna Loa Observatory Learmonth
Solar Observatory Udaipur Solar Observatory Observatorio del Teide and
the Cerro Tololo Interamerican Observatory. NSO is sponsored by
the National Science Foundation through a cooperative agreement with
the Association of Universities for Research in Astronomy Inc.

---------------------------------------------------------
Title: Interpolation and Extrapolation of Time Series
Authors: Leibacher, John
2003IAUJD..12E..45L Altcode:
Study of the temporal variation of phenomenon is often hampered by the
incompleteness of our observations. This is particularly disruptive
for highly periodic signals that are interrupted by periodic gaps which
introduce sidelobes that are difficult - if not impossible - to remove
by deconvolution techniques if the spectral peaks are dense compared to
the sidelobe separation. This is the case for the study of many classes
of variable stars including the Sun where once per day interuptions are
the norm. For signals with coherence times longer than the interuptions
there is little ambiguity as to the unobserved behaviour of the signal
- that is the frequency phase and amplitude of a mode cannot change
significantly during a time small compared with the mode lifetime -
and the missing data can be replaced with high fidelity by an iterative
procedure. The interpolated data is consistent with the observed time
series and can also be used to extrapolate the time series for times
comparable with the coherence times of the constituent modes. The method
works well for spectra of unknown content and prior information can be
simply incorporated to accelerate convergence. Applications to helio-
and astereo-seismic time series will be presented.

---------------------------------------------------------
Title: NOAO Newsletter
Authors: Isbell, Doug; Lauer, Tod R.; Bell, Dave; vanderBliek, Nicole;
Green, Richard; Hinkle, Ken; Adams, Sally; Leibacher, John; Piano,
Priscilla; Hopkins, Stephen
2002STIN...0273025I Altcode:
This journal issue is the newsletter of the National Optical
Astronomical Observatory for the month of September, 2002. It summarizes
recent research, and contains information on the US Gemini Program
(USGP), telescope access time and other issues at observatories,
operations at Kitt Peak National Observatory (KPNO), the National Solar
Observatory (NSO), as well as public affairs and educational outreach.

---------------------------------------------------------
Title: MDI and GONG inferences of the changing solar interior
Authors: Barban, C.; Howe, R.; Hill, F.; Komm, R. W.; Leibacher, J.;
Toner, C.; Bogart, R.; Braun, D.; Haber, D.; Hindman, B.; Lindsey, C.
2002ESASP.508...55B Altcode: 2002soho...11...55B
The Global Oscillation Network Group (GONG) and the Solar Oscillations
Investigation (SOI) using the Michelson Doppler Imager (MDI) instrument
aboard the SOHO spacecraft provide combined data sets that now cover
more than six years and allow us to probe the changing dynamics of the
convection zone in unprecedented detail. Here we present the latest
combined results from both projects, showing the evolution of the
migrating zonal flows close to the surface and also changes close to
and below the base of the convection zone, as well as changes in the
mode parameters related to surface magnetic activity variation in time
and latitude.

---------------------------------------------------------
Title: Natural Interpolation and Consistent Extrapolation of Time
Series arising from Dense Multi-Mode Spectra
Authors: Leibacher, J. W.
2002AAS...200.0405L Altcode: 2002BAAS...34..644L
The study of the temporal variation of phenomenon is often hampered by
the incompleteness of our observations. This is particularly disruptive
for highly periodic signals that are interrupted by periodic gaps,
which introduce sidelobes that are difficult - if not impossible -
to remove by deconvolution techniques if the spectral peaks are dense
compared to the sidelobe separation. This is the case for the study
of many classes of variable stars, including the Sun, where once per
day interruptions are the norm. However, for signals with coherence
times longer than the interruptions, there is little ambiguity as
to the unobserved behavior of the signal - that is the frequency,
phase, and amplitude of a signal cannot change significantly during a
time small compared with the signal lifetime - and the missing data
can be replaced with high fidelity, by an iterative procedure. The
interpolated data is consistent with the observed time series, and can
also be used to extrapolate the time series for times comparable with
the coherence times of the constituent modes. The method works well
for spectra of unknown content, and a priori information, e.g. the
approximate frequencies of modes, can be simply incorporated to
accelerate convergence. The National Solar Observatory is operated
under a cooperative agreement between the Association of Universities
for Research in Astronomy, Inc. and the National Science Foundation.

---------------------------------------------------------
Title: The GONG+ Network
Authors: Leibacher, J. W.
2001AGUSM..SP31A03L Altcode:
The Global Oscillation Network Group obtains helioseismic data
from a six-station network with an overall duty cycle of ≈ 90%
and will continue observing for a full solar cycle. The initial,
2562 rectangular pixel detectors are being replaced with
10242 square pixel ones, to enable high quality, continuous
local helioseismology and probing closer to the surface. The GONG+
system will also provide continuous magnetograms, and offers the
possibility of observing with a cadence as short as 16 seconds. We will
present results from the prototype GONG+ instrument and the status of
the deployment of the complete network. The Global Oscillation Network
Group (GONG) project is supported by the National Science Foundation
and operates in collaboration with the Big Bear Solar Observatory,
High Altitude Observatory, Learmonth Solar Observatory, Udaipur Solar
Observatory, Instituto de Astrofísico de Canarias, and Cerro Tololo
Interamerican Observatory.

---------------------------------------------------------
Title: Generation of Causal Time Series arising from Spectra of
Narrow-Band Asymmetric Peaks.
Authors: Leibacher, J. W.
2001AGUSM..SP31A04L Altcode:
Synthetic time series with known spectral properties are frequently used
in the development of analysis techniques, most commonly by assigning
random phases to an amplitude spectrum with the desired properties -
an approach with significant limitations. For narrow band peaks of
the sort encountered in helioseismology, a simple auto-regressive [AR]
description yields a physically realisable signal quite naturally. In
fact, a second-order AR model is just a discrete representation of the
second-order differential equation giving rise to the modes. It is
now widely appreciated that the profiles of helioseismic resonances
are significantly asymmetric, and this can be incorporated into the
generation of artificial time series quite simply by extending the
AR approach to include moving averages [MA] excitation. This ARMA
model provides an immediate source of the correlated noise that has
been invoked to describe the asymmetries. The NSO is sponsored by the
National Science Foundation through a cooperative agreement with the
Association of Universities for Research in Astronomy, Inc.

---------------------------------------------------------
Title: The GONG+ Network
Authors: Leibacher, J.
2001AAS...198.7101L Altcode: 2001BAAS...33..892L
The Global Oscillation Network Group obtains helioseismic data
from a six-station network with an overall duty cycle of ≈ 90%
and will continue observing for a full solar cycle. The initial,
2562 rectangular pixel detectors are being replaced with
10242 square pixel ones, to enable high quality, continuous
local helioseismology and probing closer to the surface. The GONG+
system will also provide continuous magnetograms, and offers the
possibility of observing with a cadence as short as 16 seconds. We will
present results from the prototype GONG+ instrument and the status of
the deployment of the complete network. The Global Oscillation Network
Group (GONG) project is supported by the National Science Foundation
and operates in collaboration with the Big Bear Solar Observatory,
High Altitude Observatory, Learmonth Solar Observatory, Udaipur Solar
Observatory, Instituto de Astrofísico de Canarias, and Cerro Tololo
Interamerican Observatory.

---------------------------------------------------------
Title: Natural Interpolation and Consistent Extrapolation of Time
Series arising from Dense Multi-Mode Spectra
Authors: Leibacher, J. W.
2001AGUSM..SP31A05L Altcode:
The study of the temporal variation of phenomenon is often hampered by
the incompleteness of our observations. This is particularly disruptive
for highly periodic signals that are interrupted by periodic gaps, which
introduce sidelobes that are difficult - if not impossible - to remove
by deconvolution techniques if the spectral peaks are dense compared to
the sidelobe separation. This is the case for the study of many classes
of variable stars, including the Sun, where once per day interuptions
are the norm. However, for signals with coherence times longer than the
interuptions, there is little ambiguity as to the unobserved behaviour
of the signal - that is the frequency, phase, and amplitude of a mode
cannot change significantly during a time small compared with the mode
lifetime - and the missing data can be replaced with high fidelity,
by an iterative procedure. The interpolated data is consistent with
the observed time series, and can also be used to extrapolate the time
series for times comparable with the coherence times of the constituent
modes. The method works well for spectra of unknown content, and a
priori information, e.g. the approximate frequenices of modes, can be
simply incorporated to accelerate convergence. The NSO is sponsored
by the National Science Foundation through a cooperative agreement
with the Association of Universities for Research in Astronomy, Inc.

---------------------------------------------------------
Title: The GONG+ Network
Authors: Leibacher, J. W.; GONG Project Team
2000SPD....31.0116L Altcode: 2000BAAS...32..803L
The Global Oscillation Network Group obtains helioseismic data
from a six-station network with an overall duty cycle of ≈ 90%
and will continue observing for a full solar cycle. The initial,
2562 rectangular pixel detectors are being replaced with
10242 square pixel ones, to enable high quality, continuous
local helioseismology and probing closer to the surface. The GONG+
system will also provide continuous magnetograms, and offers the
possibility of observing with a cadence as short as 16 seconds. We will
present results from the prototype GONG+ instrument demonstrating its
capabilities. The Global Oscillation Network Group (GONG) project
is supported by the National Science Foundation and operates in
collaboration with the Big Bear Solar Observatory, High Altitude
Observatory, Learmonth Solar Observatory, Udaipur Solar Observatory,
Instituto de Astrofísico de Canarias, and Cerro Tololo Interamerican
Observatory.

---------------------------------------------------------
Title: Oscillations of the upper chromosphere
Authors: Gouttebroze, P.; Vial, J. -C.; Bocchialini, K.; Lemaire,
P.; Leibacher, J. W.
1999SoPh..184..253G Altcode:
Variations of intensity and wavelength in several UV lines have been
observed with the SUMER spectroheliometer onboard SOHO, and they have
been analysed to obtain oscillation spectra and phase differences
between lines of different ions. Lines intensities of neutral or
singly ionized atoms (with temperature of formation ≤ 30 000 K)
exhibit an increase of oscillatory power between 2.5 and 7 mHz, which
may be considered as the signature of p modes. Lines of highly ionized
elements (with a temperature of formation ≥ 50 000 K) yield power
spectra which are continuously decreasing with frequency. Brightness
variations of the continuum at different wavelengths between 1000
and 1400 Å present oscillations in the same frequency range. Thus,
p modes seem to be efficiently stopped by the transition region. No
clear evidence is found for the existence of a chromospheric oscillation
mode. Phase comparisons between lines formed at different altitudes
(in particular Si i and Si ii) indicate that these lines oscillate in
phase, within the precision of the measurements.

---------------------------------------------------------
Title: The global oscillation network group (GONG) project
Authors: Leibacher, John W.
1999AdSpR..24..173L Altcode:
The Global Oscillation Network Group (GONG) is an international,
community-based project to conduct a detailed study of solar internal
structure and dynamics using helioseismology. In order to exploit this
technique, GONG has developed a network of six extremely sensitive
and stable solar velocity imagers to obtain nearly continuous
observations of the Sun's “five-minute” oscillations. GONG also
provides magnetograms nominally every twenty minutes. The system became
operational in October 1995, and will operate for an eleven-year
solar cycle. The observation duty cycle has averaged about 90%, and
single-site data loss due to instrument down time is less than 2%. Data
is processed at pace with the collection rate. Progress is underway to
replace the original 256 × 242 rectangular pixel cameras, with 1024
× 1024 square pixels cameras to obtain the optimal scientific return
from the instruments from the eleven-year run. There are 175 individual
members of the GONG, from 70 different institutions, and 20 nations.

---------------------------------------------------------
Title: The Global Oscillation Network Group (GONG) Project
Authors: Leibacher, John W.; GONG Project Team
1998ESASP.418....3L Altcode: 1998soho....6....3L
The Global Oscillation Network Group (GONG) is an international,
community-based project to conduct a detailed study of solar internal
structure and dynamics using helioseismology. The system became
operational in October 1995, and should operate for an eleven-year
solar cycle. There are currently 163 individual members of the GONG,
from 70 different institutions, and 20 nations. We highlight here
recent performance, results, and progress towards the replacement of
the original 256 x 256 rectangular pixel cameras with 1024 x 1024
square pixels cameras to obtain the optimal scientific return from
the instruments from the eleven-year run.

---------------------------------------------------------
Title: GONG Spectra in three observables: What is a p-mode frequency?
Authors: Harvey, J.; Hill, F.; Komm, R.; Leibacher, J.; Pohl, B.;
GONG Team
1998IAUS..185...49H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Global Oscillation Network Group (GONG)
Authors: Leibacher, J.; GONG Project Team
1997SPD....28.0211L Altcode: 1997BAAS...29..894L
The Global Oscillation Network Group (GONG) is an international,
community-based helioseismology project conducting a detailed study
of the internal structure and dynamics of the Sun. GONG is operating
a six-station network of full-disk velocity imagers exploring the
range from l = 0 to about l = 200. Full network operation began in
October 1995. The observation duty cycle has averaged about 90%, and
single-site data loss due to instrument down time is less than 2%. The
data management group is processing the network data at pace with the
collection rate. The current status, recent modifications to the data
processing system, and plans for the future will be presented.

---------------------------------------------------------
Title: Sounding solar and stellar interiors: general introduction.
Authors: Leibacher, J.
1997IAUS..181....1L Altcode:
This Symposium marks a significant milestone in the development of
helioseismology - the beginning of observations from GONG and SoHO. A
number of very significant astrophysical processes (e.g. rotational
shear induced mixing penetrative convection, diffusion, circulation
currents) have become fairly directly accessible to our sounding
using helioseismology.

---------------------------------------------------------
Title: The seismic structure of the Sun from GONG
Authors: Anderson, E.; Antia, H. M.; Basu, S.; Chaboyer, B.; Chitre,
S. M.; Christensen-Dalsgaard, J.; Eff-Darwich, A.; Elliott, J. R.;
Giles, P. M.; Gough, D. O.; Guzik, J. A.; Harvey, J. W.; Hill,
F.; Leibacher, J. W.; Kosovichev, A. G.; Monteiro, M. J. P. F. G.;
Richard, O.; Sekii, T.; Shibahashi, H.; Takata, M.; Thompson, M. J.;
Toomre, J.; Vauclair, S.; Vorontsov, S. V.
1997IAUS..181..151A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: GONG Observations of Solar Surface Flows
Authors: Hathaway, D. H.; Gilman, P. A.; Harvey, J. W.; Hill, F.;
Howard, R. F.; Jones, H. P.; Kasher, J. C.; Leibacher, J. W.; Pintar,
J. A.; Simon, G. W.
1996Sci...272.1306H Altcode:
Doppler velocity observations obtained by the Global Oscillation Network
Group (GONG) instruments directly measure the nearly steady flows in
the solar photosphere. The sun's differential rotation is accurately
determined from single observations. The rotation profile with respect
to latitude agrees well with previous measures, but it also shows a
slight north-south asymmetry. Rotation profiles averaged over 27-day
rotations of the sun reveal the torsional oscillation signal-weak,
jetlike features, with amplitudes of 5 meters per second, that are
associated with the sunspot latitude activity belts. A meridional
circulation with a poleward flow of about 20 meters per second is
also evident. Several characteristics of the surface flows suggest
the presence of large convection cells.

---------------------------------------------------------
Title: Perspectives in Helioseismology
Authors: Gough, D. O.; Leibacher, J. W.; Scherrer, P. H.; Toomre, J.
1996Sci...272.1281G Altcode:
Helioseismology is probing the interior structure and dynamics of
the sun with ever-increasing precision, providing a well-calibrated
laboratory in which physical processes can be studied under conditions
that are unattainable on Earth. Nearly 10 million resonant modes
of oscillation are observable in the solar atmosphere, and their
frequencies need to be known with great accuracy in order to gauge the
sun's interior. The advent of nearly continuous imaged observations
from the complementary ground-based Global Oscillation Network Group
(GONG) observatories and the space-based Solar and Heliospheric
Observatory instruments augurs a new era of discovery. The flow of
early results from GONG resolves some issues and raises a number of
theoretical questions whose answers are required for understanding
how a seemingly ordinary star actually operates.

---------------------------------------------------------
Title: The Current State of Solar Modeling
Authors: Christensen-Dalsgaard, J.; Dappen, W.; Ajukov, S. V.;
Anderson, E. R.; Antia, H. M.; Basu, S.; Baturin, V. A.; Berthomieu,
G.; Chaboyer, B.; Chitre, S. M.; Cox, A. N.; Demarque, P.; Donatowicz,
J.; Dziembowski, W. A.; Gabriel, M.; Gough, D. O.; Guenther, D. B.;
Guzik, J. A.; Harvey, J. W.; Hill, F.; Houdek, G.; Iglesias, C. A.;
Kosovichev, A. G.; Leibacher, J. W.; Morel, P.; Proffitt, C. R.;
Provost, J.; Reiter, J.; Rhodes, E. J., Jr.; Rogers, F. J.; Roxburgh,
I. W.; Thompson, M. J.; Ulrich, R. K.
1996Sci...272.1286C Altcode:
Data from the Global Oscillation Network Group (GONG) project and
other helioseismic experiments provide a test for models of stellar
interiors and for the thermodynamic and radiative properties, on which
the models depend, of matter under the extreme conditions found in the
sun. Current models are in agreement with the helioseismic inferences,
which suggests, for example, that the disagreement between the predicted
and observed fluxes of neutrinos from the sun is not caused by errors in
the models. However, the GONG data reveal subtle errors in the models,
such as an excess in sound speed just beneath the convection zone. These
discrepancies indicate effects that have so far not been correctly
accounted for; for example, it is plausible that the sound-speed
differences reflect weak mixing in stellar interiors, of potential
importance to the overall evolution of stars and ultimately to estimates
of the age of the galaxy based on stellar evolution calculations.

---------------------------------------------------------
Title: The Seismic Structure of the Sun
Authors: Gough, D. O.; Kosovichev, A. G.; Toomre, J.; Anderson,
E.; Antia, H. M.; Basu, S.; Chaboyer, B.; Chitre, S. M.;
Christensen-Dalsgaard, J.; Dziembowski, W. A.; Eff-Darwich, A.;
Elliott, J. R.; Giles, P. M.; Goode, P. R.; Guzik, J. A.; Harvey,
J. W.; Hill, F.; Leibacher, J. W.; Monteiro, M. J. P. F. G.; Richard,
O.; Sekii, T.; Shibahashi, H.; Takata, M.; Thompson, M. J.; Vauclair,
S.; Vorontsov, S. V.
1996Sci...272.1296G Altcode:
Global Oscillation Network Group data reveal that the internal
structure of the sun can be well represented by a calibrated standard
model. However, immediately beneath the convection zone and at the
edge of the energy-generating core, the sound-speed variation is
somewhat smoother in the sun than it is in the model. This could be a
consequence of chemical inhomogeneity that is too severe in the model,
perhaps owing to inaccurate modeling of gravitational settling or to
neglected macroscopic motion that may be present in the sun. Accurate
knowledge of the sun's structure enables inferences to be made about
the physics that controls the sun; for example, through the opacity,
the equation of state, or wave motion. Those inferences can then be
used elsewhere in astrophysics.

---------------------------------------------------------
Title: The Global Oscillation Network Group (GONG) Project
Authors: Harvey, J. W.; Hill, F.; Hubbard, R. P.; Kennedy, J. R.;
Leibacher, J. W.; Pintar, J. A.; Gilman, P. A.; Noyes, R. W.; Title,
A. M.; Toomre, J.; Ulrich, R. K.; Bhatnagar, A.; Kennewell, J. A.;
Marquette, W.; Patron, J.; Saa, O.; Yasukawa, E.
1996Sci...272.1284H Altcode:
Helioseismology requires nearly continuous observations of the
oscillations of the solar surface for long periods of time in
order to obtain precise measurements of the sun's normal modes of
oscillation. The GONG project acquires velocity images from a network
of six identical instruments distributed around the world. The GONG
network began full operation in October 1995. It has achieved a duty
cycle of 89 percent and reduced the magnitude of spectral artifacts by
a factor of 280 in power, compared with single-site observations. The
instrumental noise is less than the observed solar background.

---------------------------------------------------------
Title: Differential Rotation and Dynamics of the Solar Interior
Authors: Thompson, M. J.; Toomre, J.; Anderson, E. R.; Antia, H. M.;
Berthomieu, G.; Burtonclay, D.; Chitre, S. M.; Christensen-Dalsgaard,
J.; Corbard, T.; De Rosa, M.; Genovese, C. R.; Gough, D. O.; Haber,
D. A.; Harvey, J. W.; Hill, F.; Howe, R.; Korzennik, S. G.; Kosovichev,
A. G.; Leibacher, J. W.; Pijpers, F. P.; Provost, J.; Rhodes, E. J.,
Jr.; Schou, J.; Sekii, T.; Stark, P. B.; Wilson, P. R.
1996Sci...272.1300T Altcode:
Splitting of the sun's global oscillation frequencies by large-scale
flows can be used to investigate how rotation varies with radius
and latitude within the solar interior. The nearly uninterrupted
observations by the Global Oscillation Network Group (GONG) yield
oscillation power spectra with high duty cycles and high signal-to-noise
ratios. Frequency splittings derived from GONG observations confirm
that the variation of rotation rate with latitude seen at the surface
carries through much of the convection zone, at the base of which is
an adjustment layer leading to latitudinally independent rotation at
greater depths. A distinctive shear layer just below the surface is
discernible at low to mid-latitudes.

---------------------------------------------------------
Title: The Global Oscillation Network Group Project
Authors: Leibacher, J. W.; Harvey, J. W.; Hill, F.; Hubbard, R.;
Kennedy, J. R.; Pintar, J. A.; Bhatnagar, A.; Kennewell, J. A.;
Marquette, W.; Patron, J.; Saa, O.; Yasukawa, E.; GONG Project Team
1996AAS...188.5301L Altcode: 1996BAAS...28..903L
The NSF-sponsored Global Oscillation Network Group (GONG) project
has developed and is operating a network of six velocity imaging
instruments around the world, and a data analysis system that can keep
up with the massive data flow, in support of a vigorous community that
shares in all aspects of this program to explore the structure and
dynamics of the solar interior. Data from the first three stations
were obtained starting in March 1995, and the full six-station
network became operational in early October 1995. The system noise
is below the solar background of incoherent surface motions, and the
overall data processing pipeline is maintaining cadence with the data
flood. The scientific objectives, design and performance of the network,
instrumentation, and data processing, and plans for the future will be
presented. The National Optical Astronomy Observatories are operated
by the Association of Universities for Research in Astronomy, Inc.,
under cooperative agreement with the National Science Foundation.

---------------------------------------------------------
Title: The Solar Acoustic Spectrum and Eigenmode Parameters
Authors: Hill, F.; Stark, P. B.; Stebbins, R. T.; Anderson, E. R.;
Antia, H. M.; Brown, T. M.; Duvall, T. L., Jr.; Haber, D. A.;
Harvey, J. W.; Hathaway, D. H.; Howe, R.; Hubbard, R. P.; Jones,
H. P.; Kennedy, J. R.; Korzennik, S. G.; Kosovichev, A. G.; Leibacher,
J. W.; Libbrecht, K. G.; Pintar, J. A.; Rhodes, E. J., Jr.; Schou, J.;
Thompson, M. J.; Tomczyk, S.; Toner, C. G.; Toussaint, R.; Williams,
W. E.
1996Sci...272.1292H Altcode:
The Global Oscillation Network Group (GONG) project estimates
the frequencies, amplitudes, and linewidths of more than 250,000
acoustic resonances of the sun from data sets lasting 36 days. The
frequency resolution of a single data set is 0.321 microhertz. For
frequencies averaged over the azimuthal order m, the median formal
error is 0.044 microhertz, and the associated median fractional error
is 1.6 x 10-5. For a 3-year data set, the fractional error
is expected to be 3 x 10-6. The GONG m-averaged frequency
measurements differ from other helioseismic data sets by 0.03 to 0.08
microhertz. The differences arise from a combination of systematic
errors, random errors, and possible changes in solar structure.

---------------------------------------------------------
Title: A First Look from the GONG Helioseismology Network
Authors: Leibacher, John W.; GONG Project Team
1995AAS...18711401L Altcode: 1995BAAS...27.1447L
Helioseismology studies the internal structure and dynamics of
the Sun, utilizing very precise measurements of the frequencies of
sound waves that propagate throughout the solar interior and are
observed at the surface. These waves interfere constructively and
form resonant modes with periods near five minutes and lifetimes
ranging from weeks to many months. Their frequencies depend directly
on the temperature, composition, and motions of the regions of the
Sun through which the sound waves propagate, and we will be able to
measure these quantities in four dimensions, with remarkable resolution
in each. These measurements should provide important new knowledge
of the Sun's central temperature, the depth of its convection zone,
the abundance of helium and heavy elements, the manner in which the
interior rotates, the nature of the internal magnetic field, and how all
of these vary in time. Efforts to accurately and precisely measure the
mode frequencies from a single observing site have met with fundamental
limitations imposed by the inevitable interruptions arising from the
day-night cycle. In order to overcome these limitations, and open a
new chapter in our understanding of the Sun and stellar interiors,
the NSF-sponsored Global Oscillation Network Group (GONG) project
has developed 1) a network of six sites around the world providing
velocity images with a duty cycle better than 90%, 2) six identical
instruments with a system noise lower than the solar background of
incoherent surface motions, 3) a data processing system that can keep
up with the massive data flow, and 4) a vigorous community that has
shared in all aspects of the development of the project. Data from the
first two stations started in February 1995 and the full six-station
network became operational in early October 1995. Preliminary results
indicate that the duty cycle, daily artifact reduction, and instrument
performance goals will be met. Merging of the images from the six-sites
is being carried out, and the overall data processing pipeline appears
to be capable of maintaining cadence with the data flood.

---------------------------------------------------------
Title: Philippe Delache, 1937 - 13 October 1994.
Authors: Barlier, F.; Bonnet, R. M.; Fossat, E.; Leibacher, J.;
Frisch, U.
1995JAF....47....2B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Status of the Global Oscillation Network Group (GONG) Project
Authors: Leibacher, J. W.; GONG Project Team
1995SPD....26..102L Altcode: 1995BAAS...27..949L
No abstract at ADS

---------------------------------------------------------
Title: The Global Oscillation Network Group Project
Authors: Leibacher, J.; GONG Project Team
1995ASPC...76..381L Altcode: 1995gong.conf..381L
No abstract at ADS

---------------------------------------------------------
Title: The Global Oscillation Network Group Project
Authors: Leibacher, J. W.; GONG Project Team
1995ESASP.376a.247L Altcode: 1995heli.conf..247L; 1995soho....1..247L
The GONG Project is a community-based activity to develop and operate a
six-site, imaging helioseismic observing network, to do the basic data
reduction and provide the data and software tools to the community, and
to coordinate the scientific analysis of the data. The Project deployed
the network in 1995, and the data management and analysis center is
operational. GONG data are available to any qualified investigator
whose proposal has been accepted, however active membership in a
GONG Scientific Team will allow early access to the data and the
collaborative scientific analysis that the teams have initiated.

---------------------------------------------------------
Title: The Global Oscillation Network Group Site Survey - Part One
Authors: Hill, Frank; Fischer, George; Grier, Jennifer; Leibacher,
John W.; Jones, Harrison B.; Jones, Patricia P.; Kupke, Renate;
Stebbins, Robin T.
1994SoPh..152..321H Altcode:
The Global Oscillation Network Group (GONG) Project is planning to place
a set of instruments around the world to observe solar oscillations as
continuously as possible for at last three years. The Project has now
chosen the sites that will comprise the network. This paper describes
the methods of data collection and analysis that were used to make
this decision.

---------------------------------------------------------
Title: The Global Oscillation Network Group Site Survey - Part Two
Authors: Hill, Frank; Fischer, George; Forgach, Suzanne; Grier,
Jennifer; Leibacher, John W.; Jones, Harrison P.; Jones, Patricia
B.; Kupke, Renate; Stebbins, Robin T.; Clay, Donald W.; Ingram,
Robert E. L.; Libbrecht, Kenneth G.; Zirin, Harold; Ulrichi, Roger
K.; Websteri, Lawrence; Hieda, Lester S.; Labonte, Barry J.; Lu,
Wayne M. T.; Sousa, Edwin M.; Garcia, Charles J.; Yasukawa, Eric
A.; Kennewell, John A.; Cole, David G.; Zhen, Huang; Su-Min, Xiao;
Bhatnagar, Arvind; Ambastha, Aashok; Al-Khashlan, Abdulrahman Sa'ad;
Abdul-Samad, Muhammad-Saleh; Benkhaldoun, Zouhair; Kadiri, Samir;
Sánchez, Francisco; Pallé, Pere L.; Duhalde, Oscar; Solis, Hernan;
Saá, Oscar; González, Ricardo
1994SoPh..152..351H Altcode:
The Global Oscillation Network Group (GONG) Project will place a
network of instruments around the world to observe solar oscillations as
continuously as possible for three years. The Project has now chosen the
six network sites based on analysis of survey data from fifteen sites
around the world. The chosen sites are: Big Bear Solar Observatory,
California; Mauna Loa Solar Observatory, Hawaii; Learmonth Solar
Observatory, Australia; Udaipur Solar Observatory, India; Observatorio
del Teide, Tenerife; and Cerro Tololo Interamerican Observatory, Chile.

---------------------------------------------------------
Title: Internal Rotation of the Sun
Authors: Duvall, T. L., Jr.; Dziembowski, W.; Goode, P. R.; Gough,
D. O.; Harvey, J. W.; Leibacher, J. W.
1994snft.book..414D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A New Description of the Solar Five-Minute Oscillation
Authors: Leibacher, J.; Stein, R. F.
1994snft.book..400L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Mechanisms of Solar Variability (MSV) program
Authors: Leibacher, John W.; Noyes, Robert W.; Simon, George W.;
Neidig, Donald F.
1993STIN...9328585L Altcode:
The Mechanisms of Solar Variability (MSV) Program aims toward
understanding physical causes of variations in the radiative, magnetic,
and particle emissions from the Sun. Solar particle and field variations
influence the interplanetary medium and the magnetosphere; UV and X-ray
variations affect the Earth's upper atmosphere; and total irradiance
variations are a possibly significant perturber of tropospheric
climate. Solar magnetic variability provides a close-up arena for
studying important but otherwise unobservable astrophysical phenomena
as well. The MSV program will advance our understanding of the causes
of solar variability through high angular resolution observations
of the interaction of solar surface magnetic fields and convective
motions, as well as related x-ray, ultraviolet, and visible brightness
variations. Through these high resolution studies, MSV will complement
national programs aimed at monitoring integrated solar outputs, thus
contributing to the better understanding and ultimate predictability
of global solar variability.

---------------------------------------------------------
Title: GONG Project Update
Authors: Harvey, J.; Hill, F.; Kennedy, J.; Leibacher, J.
1993ASPC...42..397H Altcode: 1993gong.conf..397H
No abstract at ADS

---------------------------------------------------------
Title: White-light movies of the solar photosphere from the SOUP
instrument on Spacelab 2 (Advances in Space Research 1986)
Authors: Title, A. M.; Tarbell, T. D.; Simon, G. W.; Acton, L.;
Duncan, D.; Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren,
R.; Morrill, M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Topka,
K.; Harvey, J.; Leibacher, J.; Livingston, W.; November, L.
1993inas.book..100T Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Ground-based helioseismology networks
Authors: Hill, Frank; Leibacher, John
1991AdSpR..11d.149H Altcode: 1991AdSpR..11..149H
The diurnal rising and setting of the Sun severely compromises
helioseismology from a single ground-based observatory. This periodic
interruption creates sidelobes in power spectra at multiples of 1/day
(11.57 μHz) centered around each solar line, contaminating the spectra
and hampering mode identification and frequency measurement. So far,
three strategies have been used to overcome the difficulty - observing
from the Polar regions, observing with a network of stations placed
around the Earth, or observing from a fully sunlit orbit in space. This
paper reports on the status of the networks that are either currently in
operation or being planned. These include the Global Oscillation Network
Group (GONG) project, the Birmingham network, the IRIS network of the
University of Nice, the SCLERA network of the University of Arizona,
and the ESTEC network. The scientific objectives and instrumentation
of these networks are briefly described. The relationship between
networks and the helioseismology experiments on the SOHO mission
are described. Operated by the Association of Universities for
Research in Astronomy, Inc. under cooperative agreement with the
National Science Foundation.

---------------------------------------------------------
Title: The Large Earth-Based Solar Telescope (LEST) - Its Scientific
Objectives and Status
Authors: Linsky, J. L.; Leibacher, J.; Smithson, R.; Dunn, R. B.
1990BAAS...22.1238L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Large Earth-based Solar Telescope (LEST) Project
Authors: Leibacher, J. W.
1989BAAS...21..832L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Still active
Authors: Leibacher, John W.
1989Natur.337..110L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
D. M.; Shine, R. A.
1989epos.conf..303D Altcode:
The work of this team addressed the question of the response and
relationship of the flare chromosphere and transition region to the
hot coronal loops that reach temperatures of about 107K
and higher. Flare related phenomena such as surges and sprays were
also discussed. The team members debate three main topics: 1) whether
the blue-shifted components of X-ray spectral lines are signatures of
"chromospheric evaporation"; 2) whether the excess line broadening of UV
and X-ray lines is accounted for by "convective velocity distribution"
in evaporation; and 3) whether most chromospheric heating is driven by
electron beams. These debates illustrated the strengths and weaknesses
of our current observations and theories.

---------------------------------------------------------
Title: The GONG site survey.
Authors: Hill, F.; Ambastha, A.; Ball, W.; Duhalde, O.; Farris,
D.; Fischer, G.; Hieda, L.; Zhen, Huang; Ingram, B.; Jackson, P.;
Jones, H.; Jones, W.; Kennewell, J.; Kunkel, W.; Kupke, R.; Labonte,
B.; Leibacher, J.; Libbrecht, K.; Lu, W.; Morrison, L.; Odell, C.;
Pallé, P.; Saá, O.; Sousa, E.; Stebbins, T.; Xiao, Suming; GONG
Site Survey Team
1988ESASP.286..209H Altcode:
The Global Oscillation Network Group (GONG) project is planning to
place six observing stations around the world to observe the solar
oscillations as continuously as possible. This paper describes the
procedures that are being used to select the six sites. The latest
results of measurements of cloud cover obtained by networks of 6
(out of 10) radiometers show a duty cycle of over 93%, with the first
diurnal sidelobe in the window power spectrum suppressed by a factor
of 400. The results are in good agreement with the predictions of a
computer model of the expected cloud cover at individual sites.

---------------------------------------------------------
Title: The Global Oscillation Network Group (GONG)
Authors: Harvey, J. W.; Hill, F.; Kennedy, J. R.; Leibacher, J. W.;
Livingston, W. C.
1988AdSpR...8k.117H Altcode: 1988AdSpR...8..117H
As a community facility, the National Solar Observatory is establishing
a six-site ground-based solar observing network around the world. This
Global Oscillation Network Group (GONG) aims at essentially continuous
imaged observations of global solar oscillations for a minimum of three
years. Resulting data will be used to study the solar interior using
helioseismology. The heart of the observing instrument is a thermally
compensated, wide-field Fourier Techometer operated automatically by a
computer control system. Data from the six GONG stations is expected to
total over one gigabyte per day. Pipeline processing of these data will
proceed contemporaneously, reducing the raw data to several standard
product data sets at sustained throughput rates in excess of 6 megaflops
and peak rates that may exceed 50 megaflops. In support of widespread
scientific participation, software analysis tools based on the Image
Reduction and Analysis Facility (IRAF) and data distribution will be
provided. Science teams have been formed and are actively supporting
the project. The field instrument will reach the prototype stage in
early 1989 and full operation of the network is expected in 1992. Operated by the Association of Universities for Research in Astronomy,
Inc., under contract to the National Science Foundation.

---------------------------------------------------------
Title: Correlation Lifetimes of Quiet and Magnetic Granulation from
the SOUP Instrument on Spacelab 2
Authors: Title, A.; Tarbell, T.; Topka, K.; Acton, L.; Duncan, D.;
Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.; Morrill,
M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Simon, G.; Harvey,
J.; Leibacher, J.; Livingston, W.; November, L.; Zirker, J.
1988ApL&C..27..141T Altcode:
The time sequences of diffraction limited granulation images obtained by
the Solar Optical Universal Polarimeter on Spacelab 2 are presented. The
uncorrection autocorrelation limetime in magnetic regions is dominated
by the 5-min oscillation. The removal of this oscillation causes the
autocorrelation lifetime to increase by more than a factor of 2. The
results suggest that a significant fraction of granule lifetimes are
terminated by nearby explosions. Horizontal displacements and transverse
velocities in the intensity field are measured. Lower limits to the
lifetime in the quiet and magnetic sun are set at 440 s and 950 s,
respectively.

---------------------------------------------------------
Title: GONG: To See Inside Our Sun
Authors: Harvey, John W.; Kennedy, James R.; Leibacher, John W.
1987S&T....74..470H Altcode:
A world-wide program called GONG (Global Oscillation Network Group)
will permit scientists to study the depths of the sun's interior by
means of its naturally occurring oscillations. Oscillation measurements
have revealed that the rotation rate slows very slightly with deeper
penetration into the sun. Preliminary data suggest that GONG should
be able to monitor the sun 96 percent of the time; the observations
should be free from contamination by the 24-hr periodicity.

---------------------------------------------------------
Title: Ocean Waves in the Photosphere: Measurements of Oscillations
with Wavelengths of 1 - 10 Mm from SOUP White Light Images
Authors: Tarbell, T. D.; Shine, R. A.; Ferguson, S. H.; Title, A. M.;
Leibacher, J. W.
1987BAAS...19Q.936T Altcode:
No abstract at ADS

---------------------------------------------------------
Title: L'Héliosismologie Dévoile l'Intérieur du Soleil
Authors: Leibacher, J. W.; Leibacher-Ouvrard, L.
1987Rech...18..274L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Chromospheric explosions
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNeice, P.; McWhirter, R. W. P.
1986epos.conf..4.1D Altcode: 1986epos.confD...1D
Three issues relative to chromospheric explosions were debated. (1)
Resolved: The blue-shifted components of x-ray spectral lines are
signatures of chromospheric evaporation. It was concluded that
the plasma rising with the corona is indeed the primary source of
thermal plasma observed in the corona during flares. (2) Resolved:
The excess line broading of UV and X-ray lines is accounted for by a
convective velocity distribution in evaporation. It is concluded that
the hypothesis that convective evaporation produces the observed
X-ray line widths in flares is no more than a hypothesis. It is
not supported by any self-consistent physical theory. (3) Resolved:
Most chromospheric heating is driven by electron beams. Although it
is possible to cast doubt on many lines of evidence for electron
beams in the chromosphere, a balanced view that debaters on both
sides of the question might agree to is that electron beams probably
heat the low corona and upper chromosphere, but their direct impact
on evaporating the chromosphere is energetically unimportant when
compared to conduction. This represents a major departure from the
thick-target flare models that were popular before the Workshop.

---------------------------------------------------------
Title: Helioseismology
Authors: Leibacher, J. W.
1986BAAS...18R.686L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
D. M.; Shine, R. A.
1986NASCP2439....4D Altcode:
The work of this team addressed the question of the response and
relationship of the flare chromosphere and transition region to the
hot coronal loops that reach temperatures of about 107K
and higher. Flare related phenomena such as surges and sprays are
also discussed. The team members debated three main topics: 1. whether
the blue-shifted components of X-ray spectral lines are signatures of
"chromospheric evaporation"; 2. whether the excess line broadening of UV
and X-ray lines is accounted for by "convective velocity distribution"
in evaporation; and 3. whether most chromospheric heating is driven
by electron beams.

---------------------------------------------------------
Title: A Simple Irradiance Monitor for Testing Solar Global
Oscillation Network Sites
Authors: Fischer, G.; Hill, F.; Jones, W.; Leibacher, J.; McCurnin,
W.; Stebbins, R.; Wagner, J.
1986SoPh..103...33F Altcode:
We describe a simple irradiance monitor intended for use in assessing
the suitability of candidate sites for a worldwide network of small
solar telescopes. The network will observe the Sun as continuously
as possible in order to provide high quality solar oscillation data
with low diurnal sidelobe contamination and high temporal frequency
resolution.

---------------------------------------------------------
Title: White-light movies of the solar photosphere from the soup
instrument on spacelab 2
Authors: Title, A. M.; Tarbell, T. D.; Simon, G. W.; Acton, L.;
Duncan, D.; Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren,
R.; Morrill, M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Topka,
K.; Harvey, J.; Leibacher, J.; Livingston, W.; November, L.
1986AdSpR...6h.253T Altcode: 1986AdSpR...6..253T
We present initial results on solar granulation, pores and sunspots
from the white-light films obtained by the Solar Optical Universal
Polarimeter (SOUP) instrument on Spacelab 2. SOUP contains a
30-cm Cassegrain telescope, an active secondary mirror for image
stabilization, and a white-light optical system with 35-mm film
and video cameras. Outputs from the fine guidance servo provided
engineering data on the performance of the ESA Instrument Pointing
System (IPS). Several hours of movies were taken at various
disk and limb positions in quiet and active regions. The images
are diffraction-limited at 0.5 arc second resolution and are, of
course, free of atmospheric seeing and distortion. Properties of the
granulation in magnetic and non-magnetic regions are compared and are
found to differ significantly in size, rate of intensity variation,
and lifetime. In quiet sun on the order of fifty percent of the area
has at least one “exploding granule” occurring in it during a 25
minute period. Local correlation tracking has detected several types
of transverse flows, including systematic outflow from the penumbral
boundary of a spot, motion of penumbral filaments, and cellular flow
patterns of supergranular and mesogranular size. Feature tracking has
shown that in quiet sun the average granule fragment has a velocity
of about one kilometer per second.

---------------------------------------------------------
Title: Helioseismology
Authors: Leibacher, J. W.; Noyes, R. W.; Toomre, J.; Ulrich, R. K.
1985SciAm.253c..48L Altcode: 1985SciAm.253...48L
Oscillations of the sun's surface are due to sound waves resonating in
the solar interior. In actual observations, such surface displacements
are evidenced in the form of Doppler shifts in the wavelengths of
light that are absorbed by the moving gases, and as variations in
brightness. The spatial pattern and period of surface oscillation
allows investigators to deduce the three-dimensional structure of the
resonance, and to infer properties of the solar interior. Reflection
and refraction below the solar surface confine sound waves within
acoustic cavities. Such trapped waves interfere constructively with
themselves as they circle the sun, creating the resonances that are
detectable as solar surface oscillations.

---------------------------------------------------------
Title: Helioseismology.
Authors: Leibacher, J. W.; Noyes, R. W.; Toomre, J.; Ulrich, R. K.
1985SciAm.253c..34L Altcode: 1985SciAm.253...34L
Acoustic waves within the sun are visible as oscillations on the solar
surface. Their pattern and period hold clues to structure, composition
and dynamics in the sun's interior.

---------------------------------------------------------
Title: Linear models of acoustic waves in sunspot umbrae.
Authors: Gurman, J. B.; Leibacher, J. W.
1984ESASP.220..205G Altcode: 1984ESPM....4..205G
The authors interpret the 5.5 to 8.5 mHz oscillations observed in umbral
chromospheres and transition regions as acoustic waves propagating
parallel, or nearly parallel, to the temperature gradient.

---------------------------------------------------------
Title: Linear models of acoustic waves in sunspot umbrae
Authors: Gurman, J. B.; Leibacher, J. W.
1984ApJ...283..859G Altcode:
The two-dimensional, linear hydrodynamics of quiet solar and umbral
model atmospheres in a plane-parallel, adiabatic approximation
are investigated. The 5.5-8.5 mHz oscillations observed in umbral
chromospheres and transition regions are interpreted as acoustic
waves propagating parallel, or nearly parallel, to the temperature
gradient. These waves are not totally internally reflected by the steep
temperature gradient and, thus, are not trapped. Partial reflections,
however, are effective in modulating the transmission as a function
of frequency. The resonant transmission mechanism of Zugzda, Locans,
and Staude (1983) is found to produce a spectrum of resonances in the
transmission of acoustic waves in any atmosphere with a temperature
minimum. Since the observed umbral oscillations display power in only
a narrow range of frequencies, characteristics of the umbral models,
wave propagation, and observations that would tend to suppress the
higher frequency resonances are examined.

---------------------------------------------------------
Title: Internal rotation of the Sun
Authors: Duvall, T. L., Jr.; Dziembowski, W. A.; Goode, P. R.; Gough,
D. O.; Harvey, J. W.; Leibacher, J. W.
1984Natur.310...22D Altcode:
The frequency difference between prograde and retrograde sectoral
solar oscillations is analysed to determine the rotation rate of
the solar interior, assuming no latitudinal dependence. Much of the
solar interior rotates slightly less rapidly than the surface, while
the innermost part apparently rotates more rapidly. The resulting
solar gravitational quadrupole moment is J2 = (1.7+/-0.4)
× 10-7 and provides a negligible contribution to current
planetary tests of Einstein's theory of general relativity.

---------------------------------------------------------
Title: A Multiwavelength Study of a Double Impulsive Flare
Authors: Strong, K. T.; Benz, A. O.; Dennis, B. R.; Leibacher, J. W.;
Mewe, R.; Poland, A. I.; Schrijver, J.; Simnett, G.; Smith, J. B.,
Jr.; Sylwester, J.
1984SoPh...91..325S Altcode:
Extensive data from the Solar Maximum Mission (SMM) and ground-based
observatories are presented for two flares; the first occurred at
12:48 UT on 31 August, 1980 and the second just 3 min later. They were
both compact events located in the same part of the active region. The
first flare appeared as a typical X-ray flare: the CaXIX X-ray lines
were broadened (≡ 190±40 km s-1) and blue shifted (≡
60±20 km s-1) during the impulsive phase, and there was
a delay of about 30 s between the hard and soft X-ray maxima. The
relative brightness of the two flares was different depending on
the spectral region being used to observe them, the first being the
brighter at microwave and hard X-ray wavelengths but fainter in soft
X-rays. The second flare showed no significant mass motions, and the
impulsive and gradual phases were almost simultaneous. The physical
characteristics of the two flares are derived and compared. The main
difference between them was in the pre-flare state of the coronal plasma
at the flare site: before the first flare it was relatively cool (3 ×
106 K) and tenuous (4 × 109 cm-3),
but owing to the residual effects of the first flare the coronal plasma
was hotter (5 × 106 K) and more dense (3 × 1011
cm-3) at the onset of the second flare. We are led to believe
from these data that the plasma filling the flaring loops absorbed most
of the energy released during the impulsive phase of the second flare,
so that only a fraction of the energy could reach the chromosphere to
produce mass motions and turbulence.

---------------------------------------------------------
Title: Helioseismological Determination of Solar Internal Rotation
Authors: Leibacher, J.
1984LIACo..25..298L Altcode: 1984tpss.conf..298L; 1984trss.conf..298L
No abstract at ADS

---------------------------------------------------------
Title: Closed coronal structures. V - Gasdynamic models of flaring
loops and comparison with SMM observations
Authors: Pallavicini, R.; Peres, G.; Serio, S.; Vaiana, G.; Acton,
L.; Leibacher, J.; Rosner, R.
1983ApJ...270..270P Altcode:
The hydrodynamic response of confined magnetic structures to strong
heating perturbations is investigated by means of a time-dependent
one-dimensional colde which incorporates the energy, momentum, and
mass conservation equations. The entire atmospheric structure from the
chromosphere to the corona is taken into account. Models with different
energy input, heating time dependence, preflare conditions and heating
location have been examined in the numerical simulations. The
result of model calculations are compared with observations of flares
obtained with the X-ray Polychromator experiment on the Solar Maximum
Mission. These include light curves of spectral lines formed over a
wide range of coronal flare temperatures, as well as determinations
of Doppler shifts for the high temperature plasma. Several examples
are used to illustrate the range of the observational variation. It is shown that the predictions of the numerical simulations
are in good overall agreement with the observed evolution of the
flare coronal plasma. The model reproduces correctly the temporal
profile of X-ray spectral lines and -- to first order at least --
their relative intensities. The upflow velocities predicted by
model calculations are in agreement with the observed blueshifts,
supporting the interpretation of the blueshifts as due to evaporation
of chromospheric material. The possibility of using the comparison
of model predictions with observations to derive information on the
processes of energy release and transfer in solar flares is discussed.

---------------------------------------------------------
Title: X-ray line ratios from helium-like ions - Updated theory and
SMM flare observations
Authors: Wolfson, C. J.; Leibacher, J. W.; Doyle, J. G.; Phillips,
K. J. H.
1983ApJ...269..319W Altcode:
The potential which the conduction of measurements of the three
principal lines emitted from helium-like ions has for the determination
of plasma electron density was initially pointed out by Gabriel and
Jordan (1969). The diagnostic technique is based on the fact that
the ratio, R, of the intensity of a forbidden line to the intensity
of an intercombination line decreases as electron density increases
due to collisional excitation of levels. In the present investigation
a further refinement of this procedure is provided by specifically
calculating the effects of cascades from levels with principal quantum
numbers up to n=6. Two improved spectrometers recently placed in
operation include the SOLEX instrument on the satellite P78-1 and the
X-ray Polychromator (XRP) instrument on the NASA Solar Maximum Mission
satellite. Measurements obtained with one of the spectrometers making up
the XRP are presented, taking into account the emission from Ne IX ions.

---------------------------------------------------------
Title: Inner-shell transitions in Fe XIX-XXII in the X-ray spectra
of solar flares and Tokamaks
Authors: Phillips, K. J. H.; Lemen, J. R.; Cowan, R. D.; Doschek,
G. A.; Leibacher, J. W.
1983ApJ...265.1120P Altcode:
Calculated spectra of the ions Fe XIX-XXII for various densities
and temperatures are presented, thereby extending the work begun by
Doschek, Feldman, and Cowan (1981). The calculations are based on a code
(the Cowan code) that computes both the level structure of an ion and
intensity factors for the 1s-2p satellite lines. A comparison is made
between the calculated spectra and those observed in solar flares by
the P78-1 and SMM instruments. The observed intensities of Fe XX lines,
which are the most sensitive to density, are found to agree well with
those calculated in the low-density limit. The agreement for lines
arising from other ions is also very good. It is also seen that the
predicted density variations in Fe XX are confirmed by the higher
density Princeton Large Torus plasmas. Thus a possible useful density
diagnostic is indicated for tokamak and high-density astrophysical
plasmas, perhaps including some solar flares.

---------------------------------------------------------
Title: Chromospheric evaporation in a well-observed compact flare
Authors: Acton, L. W.; Leibacher, J. W.; Canfield, R. C.; Gunkler,
T. A.; Hudson, H. S.; Kiplinger, A. L.
1982ApJ...263..409A Altcode:
Hudson and Ohki (1972) pointed out that the increase of the soft
X-ray emission measure during flares might be accounted for in two
different ways, either by 'coronal condensation', or by what they termed
'chromospheric rarefaction', now more commonly called 'chromospheric
evaporation'. They ruled out coronal condensation on the basis of
cornal mass content arguments. Moore et al. (1980) found it highly
probable that the bulk of the mass of the soft X-ray emitting plasma is
supplied during the rise phase by chromospheric evaporation from the
feet of the soft X-ray loops. On the other hand, Cheng et al. (1981)
argued that chromospheric evaporation is not important as a source
of soft X-ray plasma. The present investigation is concerned with
an event in which direct chromospheric observations contradict the
conclusions reached by Cheng et al. Up to now chromospheric evaporation
has always been an inference, without compelling positive evidence. In
the current investigation, observations are considered which constitute
such evidence.

---------------------------------------------------------
Title: The Transmission and Trapping of Acoustic Waves in the Umbral
Chromosphere
Authors: Gurman, J. B.; Leibacher, J. W.
1982BAAS...14Q.939G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar atmospheric dynamics. II - Nonlinear models of the
photospheric and chromospheric oscillations
Authors: Leibacher, J.; Gouttebroze, P.; Stein, R. F.
1982ApJ...258..393L Altcode:
The one-dimensional, nonlinear dynamics of the solar atmosphere is
investigated, and models of the observed photospheric (300 s) and
chromospheric (200 s) oscillations are described. These are resonances
of acoustic wave cavities formed by the variation of the temperature
and ionization between the subphotospheric, hydrogen convection zone
and the chromosphere-corona transition region. The dependence of
the oscillations upon the excitation and boundary conditions leads
to the conclusion that for the observed amplitudes, the modes are
independently excited and, as trapped modes, transport little if any
mechanical flux. In the upper photosphere and lower chromosphere,
where the two modes have comparable energy density, interference
between them leads to apparent vertical phase delays which might be
interpreted as evidence of an energy flux.

---------------------------------------------------------
Title: Impulsive Phase of Flares in Soft X-Ray Emission
Authors: Antonucci, E.; Gabriel, A. H.; Acton, L. W.; Culhane, J. L.;
Doyle, J. G.; Leibacher, J. W.; Machado, M. E.; Orwig, L. E.; Rapley,
C. G.
1982SoPh...78..107A Altcode:
Observations using the Bent Crystal Spectrometer instrument on the
Solar Maximum Mission show that turbulence and blue-shifted motions
are characteristic of the soft X-ray plasma during the impulsive phase
of flares, and are coincident with the hard X-ray bursts observed
by the Hard X-ray Burst Spectrometer. A method for analysing the
Ca XIX and Fe XXV spectra characteristic of the impulsive phase
is presented. Non-thermal widths and blue-shifted components in the
spectral lines of Ca XIX and Fe XXV indicate the presence of turbulent
velocities exceeding 100 km s-1 and upward motions of
300-400 km s-1.

---------------------------------------------------------
Title: Solar flare X-ray spectra from the Solar Maximum Mission Flat
Crystal Spectrometer
Authors: Phillips, K. J. H.; Fawcett, B. C.; Kent, B. J.; Gabriel,
A. H.; Leibacher, J. W.; Wolfson, C. J.; Acton, L. W.; Parkinson,
J. H.; Culhane, J. L.; Mason, H. E.
1982ApJ...256..774P Altcode:
High-resolution solar X-ray spectra obtained with the Flat Crystal
Spectrometer aboard the Solar Maximum Mission from two solar flares and
a nonflaring active region are analyzed. The 1-22 A region was observed
during the flare on 1980 August 25, while smaller spectral regions were
repeatedly covered during the 1980 November 5 flare. Voigt profiles
were fitted to spectral lines to derive accurate wavelengths and to
resolve blends. During the August 25 flare, 205 lines were found in
the range 5.68-18.97 A, identifications being provided for all but 40
(mostly weak) lines. Upper limits to flare densities are derived from
various line ratios, the hotter (about 10 to the 7th K) ions giving an
electron density of less than 10 to the 12th per cu cm for the August
25 flare. Other observed line ratios (e.g., in Fe XVII and Mg XII)
indicate a need for revisions in theoretical calculations.

---------------------------------------------------------
Title: Chromospheric and coronal heating mechanisms.
Authors: Leibacher, J.; Stein, R. F.
1982SAOSR.392A..23L Altcode: 1982csss....2...23L
Dissipation mechanisms in the chromosphere were examined. The problem
of a heat flux from a cool region of the star to a hot region of the
star, which violates our second law of thermodynamics is discussed. It
is suggested that this is caused by a nonthermal energy flux. While
convection transports the thermal flux, a very small percentage is
converted into a nonthermal flux. The major part of the outgoing
convective energy is turned back into the radiation field which
gets decoupled from the star when the star becomes transparent and
the radiant energy escapes to space. The small nonthermal flux is
transmitted upwards and becomes the dominant energy flux still coupled
to the star. The importance of recycling of energy via advection and
conduction is emphasized.

---------------------------------------------------------
Title: Transition region oscillations in sunspots.
Authors: Gurman, J. B.; Leibacher, J. W.; Shine, R. A.; Woodgate,
B. E.; Henze, W.
1982ApJ...253..939G Altcode:
Time series observations of the profile of the C IV resonance
line 1548.19 A obtained in eight sunspots with the Ultraviolet
Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission are
discussed. All of the sunspots exhibit significant oscillations in
line-of-sight velocity with frequencies in the range from 5.8 mHz to
7.8 mHz (periods of 129-173 s). Significant intensity oscillations
are observed at the same periods in four of the time series; the
maximum intensity is in phase with maximum blueshift. Difference
spectroheliograms ('Dopplergrams') of the two halves of the C IV line,
as well as observations in the Si IV resonance line 1402.77 A and the
O IV intersystem line 1401.16 A, also reveal velocity oscillations at
similar frequencies but only over sunspots.

---------------------------------------------------------
Title: Direct evidence for chromospheric evaporation in a
well-observed compact flare
Authors: Canfield, R. C.; Gunkler, T. A.; Hudson, H. S.; Acton, L. W.;
Leibacher, J. W.; Kiplinger, A. L.
1982AdSpR...2k.145C Altcode: 1982AdSpR...2..145C
Observations of the solar flare of May 7, 1980 using several Solar
Maximum Mission instruments are presented as an investigation of the
phenomenon of chromospheric evaporation. The total amount of plasma
at temperatures greater than 2 x 10 to the 6th K were determined from
the X-ray data, and the amount of plasma that was evaporated from
the chromosphere was determined from the H-alpha data. The H-alpha
profiles indicate that for the flare as a whole, at the time of peak
soft X-ray emission measure, the number of atoms evaporated from the
chromosphere was 7 x 10 to the 37th. The soft X-ray emission measure
of 1 x 10 to the 49th/cu cm, coupled with the flare volume estimate
of 10 to the 26th cu cm, indicates that there were 3 x 10 to the 37th
electrons in the soft X-ray plasma with temperatures greater than 2 x
10 to the 6th K. These results indicate that enough material had been
evaporated from the chromosphere to account for the X-ray plasma. Taken
together, the H-alpha, soft X-ray, and hard X-ray images indicate that
chromospheric evaporation is driven both by flare-accelerated electrons
during the impulsive phase and by conduction during the thermal phase.

---------------------------------------------------------
Title: The Sun
Authors: Leibacher, J. W.
1982obvf.conf....3L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Oscillations and pulsations.
Authors: Leibacher, J. W.; Stein, R. F.
1981NASSP.450..263L Altcode: 1981suas.nasa..263L
A theory to describe the observed photospheric 5 minute oscillations,
chromospheric 3 minute oscillations, and possible motions of the
interior with periods ranging from 40 to 160 minutes is discussed. It
is similar to the theory of nonradial stellar oscillations developed
to describe the low angluar order modes (one or two wavelengths around
a circumference); however, the solar oscillations have thousands of
wavelengths around a circumference. The properties of waves in stars,
their restoring forces, periods and wavelengths, and their propagation
and motions are discussed.

---------------------------------------------------------
Title: Wave generation.
Authors: Stein, R. F.; Leibacher, J. W.
1981NASSP.450..289S Altcode: 1981suas.nasa..289S
There are three principal kinds of wave generation mechanisms,
corresponding to each of the three conservation laws that govern fluid
motions: a changing mass flux into a stable atmosphere; convective
motion; and energy exchange between a wave and the surrounding
atmosphere. These mechanisms are applied to three kinds of waves:
acoustic, gravity, and Alfven waves. They are pure cases, distinguished
by their different restoring forces pressure for acoustic waves,
buoyancy for gravity waves, and magnetic tension for Alfven waves.

---------------------------------------------------------
Title: SMM Observations of Soft X-Ray Line Spectra
Authors: Leibacher, J. W.; Phillips, K. J. H.; Wolfson, C. J.
1981BAAS...13..555L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Direct Evidence for Chromospheric Evaporation in a
Well-Observed Compact Flare
Authors: Canfield, R. C.; Acton, L. W.; Gunkler, T. A.; Hudson, H. S.;
Kiplinger, A. L.; Leibacher, J. W.
1981BAAS...13R.819C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Significance of Multiple Flares
Authors: Strong, K. T.; Dennis, B. R.; Leibacher, J. W.; Wolfson, C. J.
1981BAAS...13..820S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar maximum mission experiment: Early results from the soft
X-ray polychromator experiment
Authors: Gabriel, A. H.; Antonucci, E.; Phillips, K. J. H.; Culhane,
J. L.; Bentley, R. D.; Parmar, A. N.; Rapley, C. G.; Acton, L. W.;
Leibacher, J. W.; Wolfson, C. J.; Strong, K. T.; Jordan, C.
1981AdSpR...1m.267G Altcode: 1981AdSpR...1Q.267G
The X-Ray Polychromator experiment has been in operation on the
SMM satellite for over three months. It is observing flares and
active regions in the wavelength range 1Å to 23Å using a number
of different modes. These include polychromatic imaging, high
resolution line profiles, high dispersion spectra, and light curves
with high time-resolution. Data are described together with some of
the preliminary analysis and interpretation.

---------------------------------------------------------
Title: Solar Maximum Mission experiment: early results from the soft
X-ray polychromator experiment.
Authors: Gabriel, A. H.; Culhane, J. L.; Acton, L. W.; Antonucci,
E.; Bentley, R. D.; Jordan, C.; Leibacher, J. W.; Parmar, A. N.;
Phillips, K. J. H.; Rapley, C. G.; Wolfson, C. J.; Strong, K. T.
1981hea..conf..267G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: UVSP/SMM observations of transition region oscillations
in sunspots
Authors: Gurman, J. B.; Shine, R. A.; Woodgate, B. E.; Leibacher,
J. W.; Henze, W.
1981phss.conf..319G Altcode:
Using Ultraviolet Spectrometer and Polarimeter data obtained in emission
lines formed at temperatures of 70,000 K to 130,000 K, transition
region oscillations in sunspots have been observed. The frequency of
these oscillations lies in the range 5.8 mHz to 7.8 mHz. Their regular
appearance in line-of-sight velocity and their frequent occurrence in
intensity in phase with maximum blue shift leads to the interpretation
of the oscillations as upward-propagating acoustic waves. The presence
in two of the C IV wavelength 1548.19 time series of a phase-shifted
oscillation in the line width may be caused by the presence of
unidentified blends in the line wings. The energy flux carried by the
umbral acoustic waves is less than 2000 erg/sq cm/s, some seven orders
of magnitude smaller than the missing radiative flux of sunspots.

---------------------------------------------------------
Title: Velocities observed with the X-ray Polychromator onboard the
Solar Maximum Mission
Authors: Leibacher, J. W.
1980BAAS...12R.906L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Large-aperture high-resolution X-ray collimator for the Solar
Maximum Mission
Authors: Nobles, R. A.; Acton, L. W.; Joki, E. G.; Leibacher, J. W.;
Peterson, R. C.
1980ApOpt..19.2957N Altcode:
A description is presented of a flight-qualified large-aperture 12
x 12-arcsec angular resolution multigrid X-ray collimator developed
for the Solar Maximum Mission (SMM) flat crystal spectrometer. This
collimator, designed for the 1.4-22.4-A wavelength range, utilizes an
optical bench/metering structure to align and support prealigned grid
subassemblies. The optical bench is a lightweight, rigid, and stable
aluminum honeycomb structure. The grids are of a compound and bimetallic
design, having 63.5-micron square holes on an 88.9-micron spacing in
8-micron thick gold, which is in turn supported by a 76-micron thick
Invar grid having 600-micron square holes on a 739-micron spacing. The
small apertures in the gold provide the 12-arcsec collimation with
the Invar grids providing wide angle off-axis blocking out to an
approximately 35 arcmin view angle. The collimator has seven individual
channels, four of a 5.1- x 10-cm area and three of a 1.3- x 10-cm
area. Laboratory measurements gave an average angular resolution of
12.5 arcsec FWHM with 0.259 transmission for the large-area channels
and 12.0 arcsec and 0.200 transmission for the small-area channels. A
thermal filter composed of two layers of approximately 1000-A thick
aluminum prevents solar heating of the front collimator grids by
absorbing longer wavelength radiation while passing most of the X
radiation in the band of interest.

---------------------------------------------------------
Title: A Small Impulsive Flare
Authors: Acton, L. W.; Leibacher, J. W.
1980BAAS...12..904A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Spatial Dependence of UV and X-Ray Phenomena Occurring
During the Impulsive Phase of a Flare
Authors: Frost, K. J.; Dennis, B. R.; Orwig, L. E.; Kiplinger, A. L.;
Leibacher, J.; Antonucci, E.; Parmar, A. N.; Woodgate, B.; Shine,
R.; Cheng, C. -C.
1980BAAS...12..905F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar atmospheric dynamics. I - Formation of optically thick
chromospheric lines
Authors: Gouttebroze, P.; Leibacher, J. W.
1980ApJ...238.1134G Altcode:
Two of the most representative chromospheric lines, Mg II k and Ca
II K are used to study the formation of optically thick lines in a
time-dependent, one-dimensional model of the solar atmosphere. Time
sequences of these line profiles are calculated for two kinds of
atmospheric motions: propagation of a pulse through the atmosphere,
and free oscillations. The mechanisms of formation (especially
the displacement of the emitting layers) are studied for different
parts of the profiles. Finally, the deformations of the profiles
are analyzed using methods also suitable for observations, and the
resulting parameters are compared to physical variables in order to
evaluate the diagnostic methods.

---------------------------------------------------------
Title: Dynamics of the High Temperature Flare
Authors: Leibacher, J. W.
1980BAAS...12..531L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The soft X-ray polychromator for the Solar Maximum Mission.
Authors: Acton, L. W.; Culhane, J. L.; Gabriel, A. H.; Bentley,
R. D.; Bowles, J. A.; Firth, J. G.; Finch, M. L.; Gilbreth, C. W.;
Guttridge, P.; Hayes, R. W.; Joki, E. G.; Jones, B. B.; Kent, B. J.;
Leibacher, J. W.; Nobles, R. A.; Patrick, T. J.; Phillips, K. J. H.;
Rapley, C. G.; Sheather, P. H.; Sherman, J. C.; Stark, J. P.; Springer,
L. A.; Turner, R. F.; Wolfson, C. J.
1980SoPh...65...53A Altcode:
The 1.4-22.4 Å range of the soft X-ray spectrum includes a multitude
of emission lines which are important for the diagnosis of plasmas
in the 1.5-50 million degree temperature range. In particular, the
hydrogen and helium-like ions of all abundant solar elements with Z
&gt; 7 have their primary transitions in this region and these are
especially useful for solar flare and active region studies. The soft
X-ray polychromator (XRP) is a high resolution experiment working
in this spectral region. The XRP consists of two instruments with
a common control, data handling and power system. The bent crystal
spectrometer is designed for high time resolution studies in lines of Fe
I-Fe XXVI and Ca XIX. The flat crystal scanning spectrometer provides
for 7 channel polychromatic mapping of flares and active regions in
the resonance lines of O VIII, Ne IX, Mg XI, Si XIII, S XV, Ca XIX,
and Fe XXV with 14″ spatial resolution. In its spectral scanning
mode it covers essentially the entire 1.4-22.5 Å region.

---------------------------------------------------------
Title: Small-scale dissipative processes in stellar atmospheres.
Authors: Leibacher, J. W.; Stein, R. F.
1980HiA.....5..581L Altcode:
The outer atmospheres of stars must be heated by some non-thermal
energy flux to produce chromospheres and coronae. Processes are
discussed which convert the non-thermal energy flux of organized,
macroscopic motions into random, microscopic (thermal) motions. Recent
advances in the description of the chromosphere velocity field suggest
that the acoustic waves observed there transmit very little energy,
and hence are probably incapable of heating the upper chromosphere
and corona. The apparent failure of this long held mechanism and the
growing appreciation of the importance of strong magnetic fields in
the chromosphere and corona have led to hypotheses of heating by the
dissipation of currents (both oscillatory and quasi-steady). This
follows discoveries in laboratory and ionospheric plasmas and work on
solar flares, that instabilities can concentrate currents into thin
high current density filaments where they dissipate rapidly.

---------------------------------------------------------
Title: Mechanical energy transport
Authors: Stein, R. F.; Leibacher, J. W.
1980LNP...114..225S Altcode: 1980IAUCo..51..225S; 1980sttu.coll..225S
The properties, generation, and dissipation mechanisms of acoustic,
gravity and Alfven waves are described, whose restoring forces
are pressure, buoyancy, and magnetic tension, respectively. For
acoustic waves, generation by turbulent convective motions and by the
Eddington Valve thermal overstability is discussed, considering the
'five-minute' oscillation; dissipation is possible either by radiation
or shocks. Generation of gravity waves by penetrative convective
motions and by shear arising from supergranule motions is reviewed, and
dissipation due to wave breaking, interaction with the mean horizontal
fluid flow, and very severe radiative damping is considered. Attention
is given to Alfven wave generation by convective motions and thermal
overstability, and to dissipation by mode coupling, wave decay, current
dissipation, and particle collisions producing Joule or viscous heating.

---------------------------------------------------------
Title: Some Effects of Strong Acoustic Waves on Strong Spectral Lines
Authors: Gouttebroze, P.; Leibacher, J.
1980LNP...114..212G Altcode: 1980IAUCo..51..212G; 1980sttu.coll..212G
No abstract at ADS

---------------------------------------------------------
Title: Analysis of time dependent phenomena observed with the LPSP
OSO-8 instrument
Authors: Leibacher, J. W.
1979lock.reptR....L Altcode:
Data obtained by the Laboratoire de Physique Stellaire et Planetaire's
ultraviolet spectrometer onboard the OSO-8 spacecraft were analyzed
in an effort to dynamically model the solar chromosphere as an aid
in enhancing knowledge of the dynamical processes themselves and
of spectral line formation in the dynamic chromosphere. Repeated
spectral scans of strong, optically thick resonance lines formed in
the solar chromosphere were examined for indications of oscillatory
velocities and intensities among other indications of velocity which
were studied, the blue peak is reasonably well defined, and the position
of a parabolic filter fitted by the least squares method was used to
define it. Observed chromospheric oscillation periods are discussed
as well as the variations in altitude of the emitting region which
result primarily from the motion up and down during the oscillation.

---------------------------------------------------------
Title: Analysis of time dependent phenomena observed with the LPSP
OSO-8 instrument
Authors: Leibacher, J. W.
1979lock.reptQ....L Altcode:
The dynamics of the solar photosphere and chromosphere are
studied. Observations obtained by the Laboratorie de Physique Stellaire
et Planetaire's (LPSP) ultraviolet spectrometer onboard the OSO-8
spacecraft are analyzed, and dynamic models of the chromosphere and the
emitted resonance line spectrum are calculated. Some of the unpublished
data analysis and theoretical modeling which are being prepared for
publication are discussed. A discussion of the state of the theory of
velocity fields in the solar atmosphere is also presented. An invited
review presented at the OSO-8 Workshop on the topic of oscillatory
motions in the quiet sun is included. The results of the OSO-8 data
analysis prepared in close collaboration with LPSP scientists are
presented. Material for two articles is also presented.

---------------------------------------------------------
Title: A Dynamical Representation of the Solar Chromosphere
Authors: Leibacher, J. W.; Gouttebroze, P.
1978BAAS...10..671L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Simultaneous time-resolved observations of the H Lalpha ,
Mg k 2795 Å, and Ca K solar lines.
Authors: Artzner, G.; Leibacher, J.; Vial, J. C.; Lemaire, P.;
Gouttebroze, P.
1978ApJ...224L..83A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The LPSP instrument on OSO 8. II. In-flight performance and
preliminary results.
Authors: Bonnet, R. M.; Lemaire, P.; Vial, J. C.; Artzner, G.;
Gouttebroze, P.; Jouchoux, A.; Leibacher, J. W.; Skumanich, A.;
Vidal-Madjar, A.
1978ApJ...221.1032B Altcode:
The paper describes the in-flight performance for the first 18 months of
operation of the LPSP (Laboratoire de Physique Stellaire et Planetaire)
instrument incorporated in the OSO 8 launched June 1975. By means of
the instrument, an absolute pointing accuracy of nearly one second
was achieved in orbit during real-time operations. The instrument
uses a Cassegrain telescope and a spectrometer simultaneously
observing six wavelengths. In-flight performance is discussed with
attention to angular resolution, spectral resolution, dispersion
and grating mechanism (spectral scanner) stability, scattered light
background and dark current, photometric standardization, and absolute
calibration. Real-time operation and problems are considered with
reference to pointing system problems, target acquisition, and L-alpha
modulation. Preliminary results involving the observational program,
quiet sun and chromospheric studies, quiet chromospheric oscillation
and transients, sunspots and active regions, prominences, and aeronomy
investigations are reported.

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Title: Soft X-Ray Observations during the Preflare Phase of the
Solar Flare Phenomenon.
Authors: Wolfson, C. J.; Acton, L. W.; Leibacher, J. W.
1978BAAS...10..456W Altcode:
No abstract at ADS

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Title: Early evolution of an X-ray emitting solar active region.
Authors: Wolfson, C. J.; Acton, L. W.; Leibacher, J. W.; Roethig, D. T.
1977SoPh...55..181W Altcode:
The birth and early evolution of a solar active region has been
investigated using X-ray observations from the Lockheed Mapping X-Ray
Heliometer on board the OSO-8 spacecraft. X-ray emission is observed
within three hours of the first detection of Hα plage. At that time, a
plasma temperature of 4 × 106 K in a region having a density
of the order of 1010 cm−3 is inferred. During
the fifty hours following birth almost continuous flares or flare-like
X-ray bursts are superimposed on a monotonically increasing base level
of X-ray emission produced by plasma with a temperature of the order 3
× 106 K. If we assume that the X-rays result from heating
due to dissipation of current systems or magnetic field reconnection,
we conclude that flare-like X-ray emission soon after active region
birth implies that the magnetic field probably emerges in a stressed
or complex configuration.

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Title: Velocity fields in the solar atmosphere - Theory
Authors: Leibacher, J. W.
1977MmSAI..48..475L Altcode:
An attempt is made to present an equationless description of the
hydrodynamic state of the lower solar atmosphere. Areas currently being
analyzed in some depth and areas which appear amenable to treatment
are pointed out.

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Title: EUV observations of class-C X-ray flare by the LPSP
(Laboratoire de Physique Stellaire et Planétaire du Centre National
de la Recherche Scientifique) spectrometer on OSO-8.
Authors: Jouchoux, A.; Skumanich, A.; Bonnet, R. M.; Lemaire, P.;
Artzner, G.; Leibacher, J.; Vial, J. C.; Vidal-Madjar, A.
1977BAAS....9..432J Altcode:
No abstract at ADS

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Title: The LPSP experiment on OSO-8. I - Instrumentation, description
of operations, laboratory calibrations and pre-launch performances
Authors: Artzner, G.; Bonnet, R. M.; Vial, J. C.; Jouchoux, A.;
Leibacher, J.; Vidal-Madjar, A.; Lemaire, P.
1977SSI.....3..131A Altcode:
The characteristics of OSO-8, including its solar-pointed instrument
assembly and rasters, are discussed, as well as the accompanying
Laboratoire de Physique Stellaire et Planetaire (LPSP) instrumentation,
which is designed to study the solar atmosphere with high spatial,
spectral, and temporal resolution. The LPSP instrument, which consists
of two subassemblies, a Cassegrainian telescope and a spectrometer,
is described; main optical characteristics, including spectral lines
observed, and means of correcting aberrations and eliminating stray
light, are given for the spectrometer. Detectors and their capacities,
and various filter wheel configurations available for detection of
polarized light and discrimination of low orders of diffraction, are
also described. The observation program, which consists of a study of
solar prominences, flares, and dynamic and three-dimensional physical
structures of the chromosphere, as well as determination of seasonal
variations of some gases in earth's atmosphere, is reviewed. A detailed
account of pre-launch tests and calibration procedures is also given.

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Title: Extreme-Ultraviolet Observations of New Cycle Sunspots with
the LPSP Spectrometer from OSO-8
Authors: Skumanich, A.; Jouchoux, A.; Artzner, G.; Bonnet, R. M.;
Leibacher, J.; Lemaire, P.; Vial, J. C.; Vidal-Madjar, A.
1977BAAS....9..340S Altcode:
No abstract at ADS

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Title: On VI Profiles of Solar Quiet and Active Areas Recorded by
OSO-8 LPSP Experiment".
Authors: Lemaire, P.; Artzner, G.; Vial, J. C.; Bonnet, R. M.;
Gottebroze, P.; Jouchoux, A.; Vidal-Madjar, A.; McWhirter, P.;
Leibacher, J.; Skumainich, A.
1977uxsa.coll...46L Altcode: 1977IAUCo..43...46L
No abstract at ADS

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Title: OSO-8 Observations of the EUV Chromospheric Network
Authors: Artzner, G.; Bonnet, R. M.; Leibacher, J.; Lemaire, P.;
Skumanich, A.; Vial, J. C.; Vidal-Madjar, A.
1976BAAS....8..332A Altcode:
No abstract at ADS

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Title: Solar OVI Profiles as Observed by the French Experiment
Aboard OSO-8
Authors: Lemaire, P.; Artzner, G.; Bonnet, R. M.; Vial, F. C.;
Skumanich, A.; Leibacher, J.; Vidal-Madjar, A.
1976BAAS....8R.331L Altcode:
No abstract at ADS

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Title: Evolution of sunspot and active region morphology as observed
on the resonance lines of Ca+ (K, H), Mg+
(k, h), hydrogen (Lalpha , Lbeta ), and O VI from OSO-8 (LPSP).
Authors: Artzner, G.; Skumanich, A.; Bonnet, R. M.; Vidal-Madjar,
A.; Leibacher, J.; Lemaire, P.; Vial, J. C.
1976BAAS....8..397A Altcode:
No abstract at ADS

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Title: Periodic temporal phenomena in the solar chromosphere as
observed from OSO-8 (LPSP).
Authors: Vial, J. C.; Leibacher, J.; Lemaire, P.; Artzner, G.; Bonnet,
R. M.; Skumanich, A.; Vidal-Madjar, A.
1976BAAS....8..397V Altcode:
No abstract at ADS

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Title: Spatial variations of solar profiles of Ca+ H and
K, Mg+ h and k, and Lyman alpha and beta (H I) resonance
lines as observed from OSO-8 (LPSP).
Authors: Bonnet, R. M.; Artzner, G.; Leibacher, J.; Lemaire, P.;
Skumanich, A.; Vial, J. C.; Vidal-Madjar, A.
1976BAAS....8..397B Altcode:
No abstract at ADS

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Title: Prominence Observations with the OSO-8 French Experiment
Authors: Vial, J. C.; Artzner, G.; Bonnet, R. M.; Lemaire, P.;
Leibacher, J.; Skumanich, A.; Vidalmadjar, A.
1976BAAS....8..344V Altcode:
No abstract at ADS

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Title: Non linear dynamics of stellar atmospheres
Authors: Leibacher, J.; Stein, R. F.
1976pmas.conf...69L Altcode:
No abstract at ADS

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Title: Waves in the solar atmosphere.
Authors: Stein, R. F.; Leibacher, J.
1974ARA&A..12..407S Altcode:
The wave modes in the solar atmosphere are considered, taking
into account the equations of motion, pure modes, two-force modes,
and magneto-acoustic-gravity waves. Oscillations in the quiet sun
are discussed along with models of the 'five-minute' oscillation,
oscillations in regions of strong magnetic field, and nonsinusoidal
waves. Questions regarding the generation of waves are explored,
giving attention to penetrative convection, the Lighthill mechanism,
and aspects of thermal overstability. Problems regarding the heating
of the chromosphere and the corona are also examined.

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Title: A New Description of the Solar Five-Minute Oscillation
Authors: Leibacher, J. W.; Stein, R. F.
1971ApL.....7..191L Altcode: 1970ApL.....7..191L
No abstract at ADS

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Title: Solar Atmospheric Oscillations.
Authors: Leibacher, John William
1971PhDT.........1L Altcode:
No abstract at ADS

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Title: On the Five-Minute Oscillation of the Solar Atmosphere
Authors: Stein, R. F.; Leibacher, J. W.
1969ApL.....3...95S Altcode:
No abstract at ADS

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Title: 1417 Mc/sec observations of M31
Authors: Leibacher, John
1964AJ.....69..374L Altcode:
An integrated flux of 68X 10-26 W cp has been measured in a region 8
3?5 centered on M31. The spectral index appears to decrease from -0.3
to -0.6 between 158 and 1417 Mc/sec. Comparison with the distribution
of emission at lower frequencies shows no appreciable change in spectral
index over the galaxy.

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Title: 1417 Mc/s Observations of M31
Authors: Leibacher, J. W.
1964Ast....69..374L Altcode:
No abstract at ADS

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Title: 1417 Mc/sec Observations of M31.
Authors: Leibacher, John W.
1962AJ.....67Q.580L Altcode:
Lilley) .-M31 has been observed with the maser-equipped Harvard radio
telescope at 1417 Mc/sec. The low-noise temperature of the radiometer
permitted the detection of the halo of M3 1 over a region 3? 5 X 80. The
integrated value of the flux density was found to be (68*17) X 10~2e
W m-2 cps-1. Comparing this with the 408 Mc/sec flux density of Large,
Mathewson, and Haslam (Nature 183, 1250, 1959) gives a spectral index
of -0.58 *~0.13. This value should be compared with the spectral index
obtained from the flux determinations at 408 and 158 Mc/sec (Hanbury,
Brown, and Hazard, Monthly Notices Roy. Astron. Soc. 119, 297, 1959)
of 0.38*0.11. Brightness temperature profiles along the major and minor
axes at 408 and 1417 Mc/sec have been compared; and the 1417 Mc/sec
data have been smoothed and compared with the 38 and 178 Mc/sec data
of Baldwin and Costain. Both of these comparisons of the distribution
of emission show no significant differences in the distribution of
intensity across M3 1, and are thus in agreement with the results
of Costain and of Adgie and Smith for the Galaxy. The Harvard Radio
Astronomy Proj ect is supported by the National Science Foundation.