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>&gt;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