explanation blue bibcodes open ADS page with paths to full text
Author name code: marquette
ADS astronomy entries on 2022-09-14
author:"Marquette, William H."
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Title: Performance of Major Flare Watches from the Max Millennium
Program (2001 - 2010)
Authors: Bloomfield, D. S.; Gallagher, P. T.; Marquette, W. H.;
Milligan, R. O.; Canfield, R. C.
2016SoPh..291..411B Altcode: 2015arXiv151204518B; 2016SoPh..tmp....1B
The physical processes that trigger solar flares are not well
understood, and significant debate remains around processes governing
particle acceleration, energy partition, and particle and energy
transport. Observations at high resolution in energy, time, and
space are required in multiple energy ranges over the whole course of
many flares to build an understanding of these processes. Obtaining
high-quality, co-temporal data from ground- and space- based instruments
is crucial to achieving this goal and was the primary motivation for
starting the Max Millennium program and Major Flare Watch (MFW) alerts,
aimed at coordinating observations of all flares ≥ X1 GOES X-ray
classification (including those partially occulted by the limb). We
present a review of the performance of MFWs from 1 February 2001 to
31 May 2010, inclusive, which finds that (1) 220 MFWs were issued
in 3407 days considered (6.5 % duty cycle), with these occurring in
32 uninterrupted periods that typically last 2 - 8 days; (2) 56%
of flares ≥ X1 were caught, occurring in 19 % of MFW days; (3)
MFW periods ended at suitable times, but substantial gain could have
been achieved in percentage of flares caught if periods had started
24 h earlier; (4) MFWs successfully forecast X-class flares with a
true skill statistic (TSS) verification metric score of 0.500, that is
comparable to a categorical flare/no-flare interpretation of the NOAA
Space Weather Prediction Centre probabilistic forecasts (TSS = 0.488).
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Title: The Big Bear Solar Observatory Ca II K-line index for solar
cycle 23
Authors: Naqvi, M. F.; Marquette, W. H.; Tritschler, A.; Denker, C.
2010AN....331..696N Altcode:
No abstract at ADS
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Title: Synoptic Observing at Big Bear Solar Observatory
Authors: Denker, C.; Naqvi, M.; Deng, N.; Tritschler, A.; Marquette,
W. H.
2007ASPC..368..515D Altcode:
Synoptic solar observations in the chromospheric absorption lines
Ca II K and Hα have a long tradition at Big Bear Solar Observatory
(BBSO). The advent of the New Solar Telescope (NST) will shift the
focus of BBSO's synoptic observing program toward high-resolution
observations. We present an overview of the telescopes and
instrumentation and show some of the most recent results. This includes
Ca II K data to track solar irradiance variations, Hα full-disk data to
monitor eruptive events, Dopplergrams from two-dimensional spectroscopy,
as well as image restorations of diffraction-limited quality.
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Title: The New Solar Telescope at Big Bear Solar Observatory -
A Progress Report
Authors: Denker, C.; Cao, W.; Chae, J.; Coulter, R.; Kuhn, J. R.;
Marquette, W. H.; Moon, Y.; Park, Y.; Ren, D.; Tritschler, A.; Varsik,
J. R.; Wang, H.; Yang, G.; Shoumko, S.; Goode, P. R.
2005AGUSMSP43A..07D Altcode:
The New Solar Telescope (NST) is a new 1.6-meter, off-axis telescope
for the Big Bear Solar Observatory (BBSO) in California. The NST is
collaboration between BBSO, the Korean Astronomical Observatory (KAO)
and Institute for Astronomy (IfA) at the University of Hawaii. BBSO
is an ideal site for high-spatial resolution observations, since this
mountain-lake site provides consistent seeing conditions with extended
periods of excellent seeing from sunrise to sunset. These unique seeing
characteristics make BBSO ideally suited for combined high-resolution
campaigns and synoptic observations, which are essential for studies
of solar activity and space weather. In this progress report, we
present the latest information on the optical design, the optical
support structure, the telescope control system and the requisite
instrumentation for the telescope. Acknowledgements: This work has been
supported by NSF under grants ATM-0236945, ATM-0342560, MRI-0320540,
and Air Force DURIP F-49620-03-1-0271.
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Title: The New Solar Telescope at Big Bear Solar Observatory
Authors: Denker, C.; Marquette, W. H.; Varsik, J.; Wang, H.; Goode,
P. R.; Moretto, G.; Kuhn, J.; Coulter, R.
2004AAS...204.6908D Altcode: 2004BAAS...36R.795D
The New Solar Telescope (NST) at Big Bear Solar Observatory is
the replacement of the current 65 cm vacuum telescope. We present
the optical design of this novel off-axis telescope with a 1.6 m
clear aperture. The NST has been designed to exploit the excellent
seeing conditions at a lake-site observatory and provide data with a
spatial resolution close the telescope's diffraction limit from the
visible to the near-infrared (NIR) wavelength region. The post-focus
instrumentation is located in the Coudé-room, a new optical laboratory
below the observing floor, which also hosts a high-order adaptive optics
system. The main instruments are two imaging spectro-polarimeters for
visible and NIR observations and a real-time image reconstruction system
for visible-light multi-color photometry. This unique combination of
instruments will realize its full potential in the studies of active
region evolution and space weather forecasts.
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Title: First results from the NSO/NJIT solar adaptive optics system
Authors: Rimmele, Thomas R.; Richards, Kit; Hegwer, Stephen; Fletcher,
Stephen; Gregory, Scott; Moretto, Gilberto; Didkovsky, Leonid V.;
Denker, Carsten J.; Dolgushin, Alexander; Goode, Philip R.; Langlois,
Maud; Marino, Jose; Marquette, William
2004SPIE.5171..179R Altcode:
The National Solar Observatory and the New Jersey Institute of
Technology have developed two 97 actuator solar adaptive optics
(AO) systems based on a correlating Shack-Hartmann wavefront sensor
approach. The first engineering run was successfully completed
at the Dunn Solar Telescope (DST) at Sacramento Peak, New Mexico
in December 2002. The first of two systems is now operational at
Sacramento Peak. The second system will be deployed at the Big Bear
Solar Observatory by the end of 2003. The correlating Shack-Hartmann
wavefront sensor is able to measure wavefront aberrations for
low-contrast, extended and time-varying objects, such as solar
granulation. The 97-actuator solar AO system operates at a loop
update rate of 2.5 kHz and achieves a closed loop bandwidth (0dB
crossover error rejection) of about 130 Hz. The AO system is capable
of correcting atmospheric seeing at visible wavelengths during median
seeing conditions at both the NSO/Sacramento Peak site and the Big Bear
Solar Observatory. We present an overview of the system design. The
servo loop was successfully closed and first AO corrected images were
recorded. We present first results from the new, high order AO system.
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Title: Long-Term Seeing Characteristics at Big Bear Solar Observatory
Authors: Denker, C.; Espinosa, O. D.; Nenow, J.; Marquette, W. H.
2003SPD....34.2018D Altcode: 2003BAAS...35R.847D
We present observations of long-term seeing characteristics from June
1997 to September 2002 obtained with Seykora-type scintillometers
at Big Bear Solar Observatory (BBSO). BBSO is an ideal site for
ground-based campaign-style observations. Since BBSO is situated on a
small island in a 2,000 m high mountain lake in the cloudless mountains
of Souther California, it benefits from excellent seeing conditions all
day long. The atmospheric turbulence that degrades images originates
primarily from two layers near the ground and at the level of the jet
stream. BBSO's dome is located at the end of a 300 m long causeway
jutting into the lake. Since the lake, with its cool waters, provides
a natural inversion, and the dome has three kilometers of open water
to its west, the boundary layer seeing is effectively suppressed. In
addition, the east-west orientation of the Big Bear Valley provides a
natural channel for the prevailing winds from the west resulting in a
nearly laminar flow at the observatory site. We present a comparison
of scintillometer data with climate data and analyze a one year long
sub-set for local seeing variations near the lake shore and at the
observatory island. <P />We would like to thank Jacques Beckers and the
National Solar Observatory for providing the scintillometer data. This
work was supported by NSF under grant ATM 00-86999, ATM 00-76602,
and ATM 02-36945 and by NASA under grant NAG 5-9682.
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Title: Hα Full Disk Observations of Chromospheric Differential
Rotation
Authors: Smith, G. A.; Varsik, J.; Nenow, J.; Marquette, W. H.; Wang,
H.; Denker, C.
2003SPD....34.0708S Altcode: 2003BAAS...35..821S
We studied the solar chromospheric rotation profile using full-disk
Hα images of the Sun obtained at the Big Bear Solar Observatory
(BBSO). The method is based on Local Correlation Tracking (LCT). As a
unique feature the entire full-disk image is used, i. e., quiet sun
as well as solar active regions, whereas most other methods rely on
images of distinct individual features such as filaments, plages,
and sunspots. Six months of Hα full-disk data sets from June to
December 2001, which consists of 600 to 800 daily images at 30 s to 60
s cadence, have been processed and analyzed. The images were checked
for a number of problems, including overexposure, underexposure, and
skewed images. All images were normalized by having the solar disk
recentered, the dark frame subtracted, and the limb darkening function
calculated and subtracted from the image. The images are locally
cross-correlated with each other to find the displacements between
them. The angular velocities are projected onto the central meridian
and a differential rotation profile is fitted to the data (either as
Legendre polynomials or as polynomials in sin <SUP>2n</SUP>θ , quad
n=0,1, 2, ..., where θ is the heliographic longitude). The currently
used settings in the processing of the six months data were optimized
for both accuracy and speed. A number of different parameters were
experimented with, such as various grid sizes, grid spacing, sampling
window sizes, weighing functions and also different implementations of
cross-correlation algorithms, to find the best combination. <P />This
work was supported by NSF under grant ATM 00-86999, ATM 00-76602,
and ATM 02-36945 and by NASA under grant NAG 5-9682.
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Title: Solar adaptive optics: a progress report
Authors: Rimmele, Thomas R.; Richards, Kit; Hegwer, Steven L.; Ren,
Deqing; Fletcher, S.; Gregory, Scott; Didkovsky, Leonid V.; Denker,
Carsten J.; Marquette, William; Marino, J.; Goode, Philip R.
2003SPIE.4839..635R Altcode:
We present a progress report of the solar adaptive optics (AO)
development program at the National Solar Observatory (NSO) and the
Big Bear Solar Observatory (BBSO). Examples of diffraction-limited
observations obtained with the NSO low-order solar adaptive optics
system at the Dunn Solar Telescope (DST) are presented. The design
of the high order adaptive optics systems that will be deployed at
the DST and the BBSO is discussed. The high order systems will provide
diffraction-limited observations of the Sun in median seeing conditions
at both sites.
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Title: High-order adaptive optical system for Big Bear Solar
Observatory
Authors: Didkovsky, Leonid V.; Dolgushyn, Alexander; Marquette,
William; Nenow, Jeff; Varsik, John; Goode, Philip R.; Hegwer, Steven
L.; Ren, Deqing; Fletcher, Steve; Richards, Kit; Rimmele, Thomas;
Denker, Carsten J.; Wang, Haimin
2003SPIE.4853..630D Altcode:
We present a high-order adaptive optical system for the 26-inch vacuum
solar telescope of Big Bear Solar Observatory. A small elliptical
tip/tilt mirror is installed at the end of the existing coude
optical path on the fast two-axis tip/tilt platform with its resonant
frequency around 3.3 kHz. A 77 mm diameter deformable mirror with 76
subapertures as well as wave-front sensors (correlation tracker and
Shack-Hartman) and scientific channels for visible and IR polarimetry
are installed on an optical table. The correlation tracker sensor
can detect differences at 2 kHz between a 32×32 reference frame
and real time frames. The WFS channel detects 2.5 kHz (in binned
mode) high-order wave-front atmosphere aberrations to improve solar
images for two imaging magnetographs based on Fabry-Perot etalons in
telecentric configurations. The imaging magnetograph channels may work
simultaneously in a visible and IR spectral windows with FOVs of about
180×180 arc sec, spatial resolution of about 0.2 arc sec/pixel and
SNR of about 400 and 600 accordingly for 0.25 sec integration time.
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Title: Seeing Characteristic at a Lake-Site Observatory
Authors: Denker, C.; Didkovsky, L.; Marquette, W. H.; Goode, P. R.;
Venkateswaran, K.; Rimmele, T. R.
2003ASPC..286...23D Altcode: 2003ctmf.conf...23D
No abstract at ADS
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Title: Control and Acquisition Software for the Visible-Light
Fabry-Pérot Interferometer at the Big Bear Solar Observatory
Authors: Shumko, Sergiy; Denker, Carsten J.; Varsik, John; Didkovsky,
Leonid V.; Marquette, William; Goode, Philip R.; Wang, Haimin
2002SPIE.4848..483S Altcode:
We describe our progress in the development of a software package to
control a Fabry-Pérot interferometer (FPI) at the Big Bear Solar
Observatory (BBSO). The FPI is a key part of our new Visible-Light
Imaging Magnetograph (VIM). We describe the software libraries
and methods that we use to develop the software. We also present
specifications and characteristics of this new instrument.
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Title: The new global high-resolution Hα network: preliminary
results on the chromospheric differential rotation
Authors: Steinegger, M.; Denker, C.; Goode, P. R.; Marquette, W. H.;
Varsik, J.; Wang, H.; Otruba, W.; Freislich, H.; Hanslmeier, A.; Luo,
G.; Chen, D.; Zhang, Q.
2001ESASP.464..315S Altcode: 2001soho...10..315S
A new global network for high-resolution Hα full-disk observations of
the sun has been established at the Big Bear Solar Observatory (U.S.A.),
the Kanzelhöhe Solar Observatory (Austria), and the Yunnan Astronomical
Observatory (China). Each of the three stations have a 2K×2K pixel CCD
detector available to monitor the sun with a spatial resolution of 1
arcsec per pixel and a cadence of at least 1 image per minute. Having
high-cadence data from three observing stations available enables us to
accurately track solar rotation rates and meridional motions by local
correlation (LCT) and feature tracking techniques. This includes, e.g.,
tracking over several days the motions around active regions. After
an overview of the new Hα network and its scientific objectives, we
present and discuss the first preliminary results of the determination
of the chromospheric differential rotation by LCT from a high-cadence
time-series of Hα full-disk images. The obtained equatorial rotation
rate of 13.3044 deg/day (2.6876 μrad/s) agrees well with the values
obtained by other authors. Finally, we briefly outline our future
plans for the continuation of this work.
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Title: The Big Bear Solar Observatory's Digital Vector Magnetograph
Authors: Spirock, T.; Denker, C.; Chen, H.; Chae, J.; Qiu, J.; Varsik,
J.; Wang, H.; Goode, P. R.; Marquette, W.
2001ASPC..236...65S Altcode: 2001aspt.conf...65S
No abstract at ADS
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Title: Synoptic Observations of the Sun from Big Bear Solar
Observatory (CD-ROM Directory: contribs/goode)
Authors: Goode, P. R.; Denker, C.; Marquette, W. H.; Wang, H.
2001ASPC..223..656G Altcode: 2001csss...11..656G
No abstract at ADS
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Title: Dynamics of Quiet Sun Magnetic Fields
Authors: Denker, C.; Spirock, T.; Varsik, J. R.; Chae, J.; Marquette,
W. H.; Wang, H.; Goode, P. R.
2001ASPC..236..463D Altcode: 2001aspt.conf..463D
No abstract at ADS
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Title: Multi-Wavelength Observations of Solar Fine-Structure with
High Spatial Resolution (CD-ROM Directory: contribs/denker)
Authors: Denker, C.; Spirock, T. J.; Jefferies, S. M.; Chen, H.;
Marquette, W. H.; Wang, H.; Goode, P. R.
2001ASPC..223..607D Altcode: 2001csss...11..607D
No abstract at ADS
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Title: Measuring Seeing from Solar Scintillometry and the Spectral
Ratio Technique
Authors: Goode, P. R.; Wang, H.; Marquette, W. H.; Denker, C.
2000SoPh..195..421G Altcode:
In principle, the optical transfer function can be described by a
single parameter, the Fried parameter r<SUB>0</SUB>, which reveals
the net effect of the turbulence along the line of sight. We present
measurements of the Fried parameter obtained from the spectral ratio
technique and compare them to data from solar scintillometry and
from angle-of-arrival fluctuations. The measurements were performed
at the Big Bear Solar Observatory (BBSO) in 1997 and 1998 - before
and after a series of steps were taken to reduce dome seeing. The
results show that the dome seeing was considerably reduced and now
approaches the seeing conditions measured outside the dome. The Fried
parameter as measured by the spectral ratio technique now frequently
exceeds r<SUB>0</SUB>=10 cm at our lake site observatory. Accounting
for the remaining dome and window seeing, the scintillometer and the
angle-of-arrival data imply the potential for an r<SUB>0</SUB>>20
cm for BBSO during days of good seeing.
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Title: Hα Linear Polarization Observations of Solar Flares: The
Search for Proton Beams
Authors: Johns-Krull, C. M.; Fisher, G. H.; Varsik, J.; Marquette, W.
2000SPD....31.0254J Altcode: 2000BAAS...32..820J
The role of ~ 100 keV proton beams in flare energy transport is
currently unknown. Claims in the literature range from an energetically
negligible role for such protons during flares to claims that 100 keV
proton beams carry the majority of the energy released in the corona
to the photosphere during a solar flare. Much of the uncertainty
concerning protons is due to the fact that 100 keV protons produce
very few distinguishable radiative emissions. One such distinguishing
emission is the production of linear polarization in the core of the
Hα emission line during the impulsive phase of a solar flare. This
linear polarization is produced as accelerated, directed, protons
collide with ambient hydrogen atoms in the solar chromosphere. The
geometry of the situation is such that the linear polarization should
be strongest at the limb of the Sun and vanish at disk center, while the
orientation of the polarization should always be along the line between
the flare location and disk center. The expected signal is 5 -- 10%
linear polarization at the limb. We have modified the Big Bear Solar
Observatory (BBSO) video magnetograph (VMG) to operate in the core
of the Hα line. Here, we present observations of a handful of solar
flares using this system. We show that our sensitivity level is ~ 1%,
and we discuss in detail observations of a long duration GOES class
M2 flare observed at the West limb on 5 August 1999. CMJ-K would like
to acknowledge partial funding support of this work by CalSpace.
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Title: The New Global High-Resolution Hα Network: First Observations
and First Results
Authors: Steinegger, M.; Denker, C.; Goode, P. R.; Marquette, W. H.;
Varsik, J.; Wang, H.; Otruba, W.; Freislich, H.; Hanslmeier, A.; Luo,
G.; Chen, D.; Zhang, Q.
2000ESASP.463..617S Altcode: 2000sctc.proc..617S
No abstract at ADS
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Title: Large-Scale Structures of Solar Flares
Authors: Denker, C.; Marquette, W.; Wang, H.; Goode, P. R.;
Johannesson, A.
1999AAS...194.2207D Altcode: 1999BAAS...31..860D
Since December 1997, the Big Bear Solar Observatory (BBSO) has
provided daily, contrast enhanced, Hα full disk images of unsurpassed
quality, temporal resolution of about 30 s, and spatial resolution of
about 2 arcsec which allow us to study the evolution of small-scale
structures and low-contrast features. This data set has the right
qualities to allow us to study large-scale phenomena associated with
major solar flares such as Moreton waves, transient brightening of
the Hα network, filament eruptions and disappearances. In 1998, 31
flares of magnitude M3.0 or larger were observed by the Geosynchronous
Operational Environmental Satellites (GOES). Eight of them occurred
during the typical observing hours at BBSO and seven were actually
covered by Hα full disk observations presented here. We provide a
detailed description of various chromospheric disturbances initiated by
the flares, the influence of magnetic fields on their appearance, and
their association with coronal mass ejections. This work was supported
by ONR under grant N00014-97-1-1037, by NSF under grant ATM 97-14796,
and by NASA under grant NAG 5-4919 and NAG 5-7350.
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Title: Solar Asphericities from BBSO Synoptic Data and MDI Splittings
Authors: Goode, P. R.; Dziembowski, W. A.; Marquette, W.
1999AAS...194.4205G Altcode: 1999BAAS...31..882G
Beneath the photosphere, on average the Sun is almost a perfect
sphere. Historically, the main photospheric asymmetry studied has been
the magnetic activity cycle as reflected in the Maunder butterfly
diagram. In recent years, more subtle signatures of asymmetries
varying with the solar cycle have been found. We have used temporal
averages of BBSO synoptic maps from the activity minimum which has just
ended to extract the low degree Legendre dependence of the data. We
present preliminary comparisons of the degree of correlation between
these Legendre coefficients varying through the solar cycle with the
temporally corresponding low degree Legendre coefficents from MDI
splitting data to enable us to garner another perspective, the role
of the magnetic field in the Sun's cycle dependent asphericity.
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Title: Acoustic Imaging in Helioseismology
Authors: Chou, Dean-Yi; Chang, Hsiang-Kuang; Sun, Ming-Tsung; LaBonte,
Barry; Chen, Huei-Ru; Yeh, Sheng-Jen; TON Team; Tang, Heng-Tai; Shiu,
Wei-Cheng; Chen, Yi-Liang; Jimenez, Antonio; Rabello-Soares, Maria
Cristina; Ai, Guoxiang; Wang, Gwo-Ping; Goode, Philip; Marquette,
William; Ehgamberdiev, Shuhrat; Khalikov, Shukur
1999ApJ...514..979C Altcode:
The time-variant acoustic signal at a point in the solar interior can
be constructed from observations at the surface, based on the knowledge
of how acoustic waves travel in the Sun: the time-distance relation
of the p-modes. The basic principle and properties of this imaging
technique are discussed in detail. The helioseismic data used in
this study were taken with the Taiwan Oscillation Network (TON). The
time series of observed acoustic signals on the solar surface is
treated as a phased array. The time-distance relation provides the
phase information among the phased array elements. The signal at any
location at any time can be reconstructed by summing the observed
signal at array elements in phase and with a proper normalization. The
time series of the constructed acoustic signal contains information on
frequency, phase, and intensity. We use the constructed intensity to
obtain three-dimensional acoustic absorption images. The features in
the absorption images correlate with the magnetic field in the active
region. The vertical extension of absorption features in the active
region is smaller in images constructed with shorter wavelengths. This
indicates that the vertical resolution of the three-dimensional images
depends on the range of modes used in constructing the signal. The
actual depths of the absorption features in the active region may be
smaller than those shown in the three-dimensional images.
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Title: Synoptic Hα Full-Disk Observations of the Sun from Big
Bear Solar Observatory - I. Instrumentation, Image Processing,
Data Products, and First Results
Authors: Denker, C.; Johannesson, A.; Marquette, W.; Goode, P. R.;
Wang, H.; Zirin, H.
1999SoPh..184...87D Altcode:
The Big Bear Solar Observatory (BBSO) has a long tradition of synoptic
full-disk observations. Synoptic observations of contrast enhanced
full-disk images in the Ca ii K-line have been used with great success
to reproduce the H i Lα irradiance variability observed with the
Upper Atmosphere Research Satellite (UARS). Recent improvements in
data calibration procedures and image- processing techniques enable us
now to provide contrast enhanced Hα full-disk images with a spatial
resolution of approximately 2” and a temporal resolution of up to 3
frames min−1.
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Title: New Digital Magnetograph At Big Bear Solar Observatory
Authors: Wang, H.; Denker, C.; Spirock, T.; Goode, P. R.; Yang, S.;
Marquette, W.; Varsik, J.; Fear, R. J.; Nenow, J.; Dingley, D. D.
1998SoPh..183....1W Altcode:
A new digital magnetograph system has been installed and tested at
Big Bear Solar Observatory. The system uses part of BBSO's existing
videomagnetograph (VMG) system: a quarter wave plate, a ferro-electric
liquid crystal to switch polarizations, and a 0.25 Å bandpass Zeiss
filter tuned at Ca i 6103 Å. A new 256×256 pixels, 12-bit Dalsa
camera is used as the detector and as the driver to switch the liquid
crystal. The data rate of the camera is 90 frames s−1. The camera
is interfaced to a Pentium-166 PC with a μTech imaging board for data
acquisition and analysis. The computer has 128 MByte of RAM, and up to
700 live images can be stored in memory for quick post-exposure image
processing (image selection and alignment). We have significantly
improved the sensitivity and spatial resolution over the old BBSO
VMG system. In particular: (1) New digital image data are in 12 bits
while the video signal is digitized as 8 bits. Polarizations weaker
than 1% can not be detected by a single pair subtraction in the video
system. The digital system can detect a polarization signal of about
0.3% by a single pair subtraction. (2) Data rate of the digital system
is 90 frames s−1, that of the video system is 30 frames s−1. So
the time difference between two polarizations is reduced in the new
system. Under good seeing conditions, the data rate of 90 frames
s−1 ensures that most of the wavefront distortions are `frozen'
and fairly closely the same for the left and right circular polarized
image pairs. (3) Magnetograms are constructed after image selection
and alignment. We discuss the characteristics of this new system. We
present the results of our first tests to reconstruct magnetograms with
speckle interferometric techniques. We also present some preliminary
results on the comparison of facular/micropore contrasts and magnetic
field structure. The experiment with this small detector lays ground
for a larger format digital magnetograph system at BBSO, as well as
a future Fabry-Pérot system, which will be able to scan across the
spectral line.
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Title: Magnetic Sources of the Solar Irradiance Cycle
Authors: Lean, J. L.; Cook, J.; Marquette, W.; Johannesson, A.
1998ApJ...492..390L Altcode:
Using recently processed Ca K filtergrams, recorded with a 1 Å
filter at the Big Bear Solar Observatory (BBSO), we quantitatively
assess the component of solar irradiance variability attributable to
bright magnetic features on the Sun's disk. The Ca K filtergrams,
“flattened” by removing instrumental effects and center-to-limb
variations, provide information about bright sources of irradiance
variability associated with magnetic activity in both active regions and
dispersed active region remnants broadly distributed in the supergranule
network (termed collectively “faculae”). Procedures are developed
to construct both total and UV spectral solar irradiance variations
explicitly from the processed Ca K filtergrams, independently of
direct irradiance observations. The disk-integrated bolometric and
UV facular brightness signals determined from the filtergrams between
late 1991 and mid-1995 are compared with concurrent solar irradiance
measurements made by high-precision solar radiometers on the Upper
Atmosphere Research Satellite (UARS). The comparisons suggest that
active-region and active-network changes can account for the measured
variations. This good agreement during a period covering most of the
decline in solar activity from the cycle 22 maximum to the impending
solar minimum directly implicates magnetic features as the sources
of the 11 yr irradiance cycle, apparently obviating the need for an
additional component other than spots or faculae.
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Title: A 10-Year Set of CA I K-Line Filtergrams
Authors: Johannesson, Anders; Marquette, William H.; Zirin, Harold
1998sers.conf..265J Altcode:
No abstract at ADS
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Title: A 10-Year Set of CA II K-Line Filtergrams
Authors: Johannesson, Anders; Marquette, William H.; Zirin, Harold
1998SoPh..177..265J Altcode:
We have processed a 10-year set of BBSO Caii K-line filtergrams covering
most of solar cycle 22. The excess K-line emission is integrated to
form linear and square-root activity indices that are fitted to UV data
from UARS and SME. Good fits are found both for the Mgii core-wing ratio
(linear) and total Lα irradiance (square root) and the indices are thus
good proxies for UV data. The SME Lα irradiance is systematically lower
by 20% than predicted from our corresponding K-line indices. The 10.7
cm radio data confirms that SME underestimated the flux. The network
is partly responsible for the solar cycle variation of the indices
and is relatively more important in Lα than in Mgii and Caii K. This
is due to the saturation of Lα equivalent width. We also report on
substantial improvements to the equipment and reduction software. The
system is now based on a digital CCD camera which promises more accurate
measurements in the upcoming solar cycle 23.
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Title: Comparison of Polar and Equatorial Magnetic Fields Near
Sunspot Minimum
Authors: Zhang, L. D.; Zirin, H.; Marquette, W. H.
1997SoPh..175...59Z Altcode:
We investigate the polar magnetic fields near sunspot minimum
using high-resolution videomagnetograph data from Big Bear Solar
Observatory. To avoid the problem of center-to-limb variation of the
projected longitudinal field, we compare polar with equatorial field
strengths for the same limb distance. Polar fields are stronger than
the quiet equatorial field, but no greater than equatorial limb data
containing unipolar regions. The difference is entirely in the stronger
field elements. The polar background fields are of mixed polarity
but show a net weak field opposite in sign to that of the stronger
polar elements. We believe this to be the first evidence of widespread
background field. No dependence of the measured signal on the B-angle
was found, so the high-latitude fields do not change strength near the
pole. Further, there was no significant change in the polar fields in
the 15-month period studied. We tried to derive a high-latitude rotation
rate; our data show motion of high-latitude magnetic elements, but the
diurnal trajectory is not much bigger than random motions and field
changes, so the result is inconclusive. We suggest that the polar
fields represent the accumulation of sunspot remnants, the elements
of which last for years in the absence of other fields.
---------------------------------------------------------
Title: Comparison of Two Fitting Methods for Ring Diagram Analysis
of Very High l Solar Oscillations
Authors: Patrón, J.; González Hernández, I.; Chou, Dean-Yi;
Sun, M. -T.; Mu, T. -M.; Loudagh, S.; Bala, B.; Chou, Y. -P.; Lin,
C. -H.; Huang, I. -J.; Jiménez, A.; Rabello-Soares, M. C.; Ai, G.;
Wang, G. -P.; Zirin, H.; Marquette, W.; Nenow, J.; Ehgamberdiev, S.;
Khalikov, S.; TON Team
1997ApJ...485..869P Altcode:
A new method of fitting tridimensional power spectra of solar
oscillations is described and compared with a previous one whose
use has been more common. The new method fits the parameters of the
Lorentzian profiles in a bidimensional k - ω diagram constructed
from an azimuthal average of the tridimensional one. The horizontal
velocities are then determined keeping these parameters fixed, greatly
reducing the computation time. Both methods are compared for two radial
orders (n = 3, 4) of a tridimensional power spectrum obtained for a
region of about 15° square around solar disk center. The images used
in this work correspond to a 3 day set of 1080 × 1080 pixel intensity
images obtained at the Observatorio del Teide on 1994 November 8-10
with the Taiwanese Oscillation Network (TON) instrument. The results
of the fitted velocities agree within the estimated errors for the
two methods. The reduction of the computing time obtained with the
new method makes it convenient for the ring diagram analysis.
---------------------------------------------------------
Title: Modeling solar extreme ultraviolet irradiance variability
using emission measure distributions
Authors: Warren, H. P.; Mariska, J. T.; Lean, J.; Marquette, W.;
Johannesson, A.
1996GeoRL..23.2207W Altcode:
We introduce a new model of solar irradiance variability at extreme
ultraviolet (EUV) wavelengths. The model combines a spectral emission
line database, solar emission measure distributions, and estimates
from ground-based solar images of the fraction of the Sun covered by
the various types of activity to synthesize the irradiance. Using Call
K-line images, the model can be used to estimate the irradiance from
EUV line emission formed in the upper chromosphere and lower transition
region. Comparisons of this new model with existing empirical models
reveal both similarities and disagreements in the absolute magnitude,
the amplitude of the rotational modulation, and the intermediate-term
solar cycle variability of the predicted fluxes.
---------------------------------------------------------
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: Facular Origin of the Sun's 11-year Total Radiation Cycle
Authors: Lean, J.; Cook, J.; Marquette, W.; Johannesson, A.;
Willson, R.
1996AAS...188.7901L Altcode: 1996BAAS...28Q.955L
While the amplitude and temporal structure of the 11-year cycle in the
Sun's total radiation is relatively well established from spacebased
radiometry, the origins of the variations are not. Rotational modulation
on shorter time scales is attributable to the changing presence on the
Sun's Earth-facing disk of dark sunspots and bright faculae, both of
which occur frequently during times of high solar activity but may be
absent for days during solar minimum conditions. However, calculations
of the energy changes in sunspots and active region faculae over the
longer time scale of the 11-year cycle underestimate the observed solar
cycle irradiance modulation by about a factor of two. This apparent lack
of facular brightness has lead to speculation of a missing irradiance
brightness component, and the possibility that a non facular -- perhaps
global -- mechanism may be responsible for the observed total radiation
energy changes. Recent analysis of Ca K filtergrams, recorded with a 1
Angstrom Daystar filter at the BBSO, suggest a methodology with which to
quantitatively assess the contribution of facular brightness to total
solar irradiance variations. Following removal of instrumental effects
and limb variations from the Ca K images, the resultant "flattened"
spectroheliograms provide a surrogate for facular brightness in both
active regions and in the surrounding chromospheric network. Evolution
of the globally integrated signal from enhanced Ca K emission on the
full solar disk is compared with concurrent total solar irradiance
measurements made by the ACRIM II radiometer on the Upper Atmosphere
Research Stellite from 1992 to 1994. This period covers most of the
decline in solar activity from the cycle 22 maximum to the impending
solar minimum, and suggest that facular changes can account for
essentially all the measured variations.
---------------------------------------------------------
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: Reproduction of the Lyman \alpha Irradiance Variability from
Analysis of Full-Disk Images in the CaII K-Line
Authors: Johannesson, A.; Marquette, W.; Zirin, H.
1995SoPh..161..201J Altcode:
We have compared three years of daily CaII K-line images from the Big
Bear Solar Observatory (BBSO) with HI Lymanα irradiance data from the
Upper Atmosphere Research Satellite (UARS). The daily full-disk CaII
K-line images are reduced to a new index of integrated excess emission,
which reproduces both the 27 day rotational modulation and the solar
cycle decrease in Lyα irradiance. Our analysis shows that while plages
reproduce the 27-day variation quite well, the total K-line emission
excess above the quiet background is needed to reproduce the secular
solar cycle trend in the Lyα irradiance. The resulting K-line index
exhibits a high degree of correlation (0.9) with the time series of
measured Lyα flux.
---------------------------------------------------------
Title: Taiwan Oscillation Network
Authors: Chou, Dean-Yi; Sun, Ming-Tsung; Huang, Teng-Yi; Lai,
Shih-Ping; Chi, Pi-Jen; Ou, Knight-Tien; Wang, Chang-Chi; Lu,
Jui-Yang; Chu, An-Li; Niu, Chi-Seng; Mu, Tao-Mo; Chen, Kuan-Rong;
Chou, Yung-Ping; Jimenez, Antonio; Rabello-Soares, Maria Cristina;
Chao, Horance; Ai, Guoxiang; Wang, Gwo-Ping; Zirin, Harold; Marquette,
William; Nenow, Jeff
1995SoPh..160..237C Altcode:
The Taiwan Oscillation Network (TON) is a ground-based network to
measure solar intensity oscillations to study the internal structure
of the Sun. K-line full-disk images of 1000 pixels diameter are taken
at a rate of one image per minute. Such data would provide information
onp-modes withl as high as 1000. The TON will consist of six identical
telescope systems at proper longitudes around the world. Three telescope
systems have been installed at Teide Observatory (Tenerife), Huairou
Solar Observing Station (near Beijing), and Big Bear Solar Observatory
(California). The telescopes at these three sites have been taking
data simultaneously since October of 1994. Anl - v diagram derived
from 512 images is included to show the quality of the data.
---------------------------------------------------------
Title: A ground-based CaII K-line index as a proxy for the UARS
Lyman α irradiance
Authors: Johanesson, A.; Marquette, W.; Zirin, H.
1995SPD....26..511J Altcode: 1995BAAS...27..959J
No abstract at ADS
---------------------------------------------------------
Title: Calcium Plage Observations at Big Bear Solar Observatory
Authors: Marquette, W.
1992sers.conf..154M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Solar Cycle Pattern in the Direction of the Magnetic
Field along the Long Axes of Polar Filaments
Authors: Martin, Sara F.; Marquette, William H.; Bilimoria, Rajash
1992ASPC...27...53M Altcode: 1992socy.work...53M
No abstract at ADS
---------------------------------------------------------
Title: The Evolution and Orientation of Early SOLAR-CYCLE-22 Active
Regions
Authors: Cannon, Anne T.; Marquette, William H.
1991SoPh..131...69C Altcode:
The evolution of six major active regions which appeared during the
first phase of the present solar cycle (cycle 22) has been studied. It
was found that the northern hemisphere regions exhibited a broad range
of evolutionary behavior in which the commonly accepted `normal pattern'
(whereby the follower flux moves preferentially polewards ahead of
the leader flux) is represented only at one end of the range. At the
other end of the range, the leader flux is displaced polewards of the
follower flux. In the latter cases equatorward extensions of the polar
coronal hole are noted.
---------------------------------------------------------
Title: Modelling solar irradiances using ground-based measurements
Authors: Pap, J. M.; Marquette, W. H.; Donnelly, R. F.
1991AdSpR..11e.271P Altcode: 1991AdSpR..11..271P
The preliminary results of the photometry of Ca-K plage remnants
show that during the fall of 1986 the remnants gave a significant
contribution to the irradiance variations. The contribution of the
plage remnants to the combined plage and remnant index was on average
about 13 % and it changed with time.
---------------------------------------------------------
Title: BEARALERTS: A successful flare prediction system
Authors: Zirin, Harold; Marquette, William
1991SoPh..131..149Z Altcode:
We describe our BEARALERT program of predicting solar flares or rapid
development of activity in certain sunspot groups. The purpose of the
program is to test our understanding of the flare process by making
public predictions via electronic mail. Neither the exact timing
of the flare nor the possibility of emergence of new active regions
can be predicted. But high-resolution observations of the magnetic
configuration, Ha brightness and structure and other properties of
a region enabled us to announce the onset of 15 of 23 major active
regions over a two-year period, and 15 of 32 BEARALERTS were followed
by this activity. We used high-resolution real-time data available
at the Big Bear Solar Observatory (BBSO). The criteria for prediction
are given and discussed, along with those for filament eruption.
---------------------------------------------------------
Title: The Orientation of Early Cycle Active Regions and the Polar
Coronal Hole
Authors: Cannon, A. T.; Marquette, W. H.
1990BAAS...22..873C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Anomalous Orientations of the Polarities In Decaying Active
Regions
Authors: Cannon, A. T.; Marquette, W. H.
1989BAAS...21..839C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: BEARALERTS: A New Program of Flare Prediction
Authors: Marquette, W.; Zirin, H.
1989BAAS...21..836M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Development of Noble Liquid Detectors for Gamma Ray
Spectroscopy.
Authors: Marquette, William H.; Martin, Sara F.
1988SoPh..117..227M Altcode:
We describe the decay phase of one of the largest active regions of
solar cycle 22 that developed by the end of June 1987. The center of
both polarities of the magnetic fields of the region systematically
shifted north and poleward throughout the decay phase. In addition,
a substantial fraction of the trailing magnetic fields migrated
equatorward and south of the leading, negative fields. The result of
this migration was the apparent rotation of the magnetic axis of the
region such that a majority of the leading polarity advanced poleward at
a faster rate than the trailing polarity. As a consequence, this region
could not contribute to the anticipated reversal of the polar field.
---------------------------------------------------------
Title: New Information on the Spatial Distribution of Active Regions
Authors: Martin, S. F.; Hermans, L. M.; Marquette, W. H.
1981BAAS...13..551M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Factors Related to the Eruption of Quiescent Filaments
Authors: Hermans, L. M.; Martin, S. F.; Marquette, W. H.
1980BAAS...12..914H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Comparison of Solar Cycle 21 with Previous Solar Cycles
Authors: Marquette, W. H.; Martin, S. F.
1980BAAS...12..508M Altcode:
No abstract at ADS