%...Journal: PASP
%...MainTag: '<UCP-HEADER'
%R=BibCode
%A=Authors
%B=Abstract
%c=Copyright
%D=Date of publication
%E=Electronic file
%F=Original File
%I=Institute and/or Footnotes
%J-last page
%K=Keywords
%T=Title
%Z=Editor's Notes sup. meterial

%R 2002PASP..114.1051S
%F ori/PASPv114n800 
%J-1069
%T Deconvolution in Astronomy: A Review. (Review).
%A Starck, J.L.
%A Pantin, E.
%I Service d'Astrophysique, SAP/SEDI, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex,
   France; (jstarck@cea.fr), (epantin@cea.fr)
%A Murtagh, F.
%I School of Computer Science, Queen's University Belfast, Belfast BT7 1NN,
   Northern Ireland; and Observatoire de Strasbourg, Universit\'e Louis Pasteur,
   F-67000 Strasbourg, France; (f.murtagh@qub.ac.uk)
%B This article reviews different deconvolution methods. The all-pervasive
   presence of noise is what makes deconvolution particularly difficult. The
   diversity of resulting algorithms reflects different ways of estimating the
   true signal under various idealizations of its properties. Different ways
   of approaching signal recovery are based on different instrumental noise
   models, whether the astronomical objects are pointlike or extended, and indeed
   on the computational resources available to the analyst. We present a number
   of recent results in this survey of signal restoration, including in the
   areas of superresolution and dithering. In particular, we show that most
   recent published work has consisted of incorporating some form of multiresolution
   in the deconvolution process.
%K Methods: Data Analysis
%K Techniques: Image Processing

%R 2002PASP..114.1070S
%F ori/PASPv114n800 
%J-1086
%T A New Method for Computing Differential Color Refraction.
%A Stone, Ronald C.
%I US Naval Observatory, Flagstaff Station, P.O. Box 1149, Flagstaff, AZ 86002;
   (rcs@nofs.navy.mil)
%B A new method for computing differential color refraction (DCR) is presented
   in this paper that uses observations taken through a conventional filter
   as well as through a narrowband interference filter that serves as a template
   for the reductions. The method is tested with observations taken through
   Johnson {\em BV} and Cousins {\em RI} filters, and, in general, there is
   good agreement (excellent in all but one case) between observed and predicted
   values of DCR. A full description of the method is given as well as a discussion
   of the refraction model used to make the predictions. As expected, DCR is
   strongest in the {\em B} passband and weakest in the {\em I} band because
   of the wavelength dependence of atmospheric refraction. Furthermore, the
   common practice of calibrating DCR against a stellar color is investigated,
   finding that the procedure is justified, albeit the intrinsic scatter in
   the calibration can vary widely with the choice for the color. This scatter
   can be minimized with a judicious choice for the color system, and examples
   are given for the {\em BVRI} passbands considered in the paper. Nonetheless,
   there will always be some remaining error caused by the calibrating process,
   which will affect mostly star positions determined at large zenith distances.
   Further gains in positional accuracy are possible by choosing a passband
   for which the DCR is very small. Two such passbands are the Cousins {\em
   I} band (FWHM=1900 {AA}) and the passband (FWHM=630 {AA}) chosen for the USNO CCD
   Astrograph Catalog project. The ranges in the DCR for these passbands are,
   respectively, only 19 and 12 mas at a zenith distance of ZD=60{deg}. When calibrated
   against stellar color, remaining errors in the DCR calibrations for both
   of these passbands are expected to be under 5 mas. In the final section of
   the paper, numerical results are given for other possible passbands with
   small ranges ({<=}20 mas) in DCR.
%K Astrometry

%R 2002PASP..114.1087L
%F ori/PASPv114n800 
%J-1091
%T Noise and the Strong-Signal Limit in Radio Astronomical Measurement.
%A Liszt, H.
%I National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville,
   VA 22903-2475; (hliszt@nrao.edu)
%B The random error of radio astronomical measurements is usually computed
   in the weak-signal limit, which assumes that the system temperature is sensibly
   the same on and off source, or with and without a spectral line. This assumption
   is often very poor. We give examples of common situations in which it is
   important to distinguish the system noise in signal-bearing and signal-free
   regions.
%K Instrumentation: Miscellaneous
%K Methods: Data Analysis
%K Methods: Statistical

%R 2002PASP..114.1092N
%F ori/PASPv114n800 
%J-1096
%T Interpretations of the Accelerating Universe.
%A Narlikar, J.V.(1)
%A Vishwakarma, R.G.(1)
%A Burbidge, G.(2)
%B It is generally argued that present cosmological observations support
   the accelerating models of the universe, as driven by a cosmological constant
   or ``dark energy.'' We argue here that an alternative model of the universe
   is possible, which explains the current observations of the universe. We
   demonstrate this with a reinterpretation of the magnitude-redshift relation
   for Type Ia supernovae, since this was the test that gave a spurt to the
   current trend in favor of the cosmological constant.
%K Cosmology: Theory
%I (1) Inter-University Centre for Astronomy and Astrophysics, Post Bag
   4, Pune 411007, India.
%I (2) Center for Astrophysics and Space Sciences, Box 0424, University
   of California, San Diego, CA 92093-0424.

%R 2002PASP..114.1097S
%F ori/PASPv114n800 
%J-1107
%T CN Abundance Inhomogeneities in the Globular Cluster M3: Results Based on
   Merged Data Sets from the Literature.
%A Smith, Graeme H.
%I University of California Observatories/Lick Observatory, University of California,
   Santa Cruz, CA 95064; (graeme@ucolick.org)
%B Measurements of the {lambda}3883 CN band absorption strength in spectra
   of red giant members of the globular cluster M3 have been compiled from several
   sources in the literature, including the pioneering survey of N. B. Suntzeff,
   and transformed onto a common system. The homogenized indices give a picture
   of the behavior of the CN band strength over a range in stellar magnitude
   of ~3.6 mag, from the tip of the red giant branch (RGB) to M_V_~+1.0. As
   with other well-studied globular clusters, the red giant branch stars of
   M3 exhibit a bimodal distribution of CN band strengths that extends to the
   limit of the available survey. The asymptotic giant branch stars also show
   evidence of an intrinsic spread in CN content. Anticorrelations exist between
   the CN band strength and both carbon and oxygen abundances, suggesting that
   the high nitrogen abundances of the CN-strong giants have derived from a
   conversion of C and/or O into nitrogen, either within the cluster stars themselves
   or in some primordial site. Among both CN-strong and CN-weak stars, the [C/Fe]
   abundance decreases with increasing luminosity on the RGB. Stellar atmosphere
   models indicate that in the magnitude range -1.5<M_V_<0, the CxN abundance
   product is roughly constant among the CN-weak giants, while it decreases
   toward the upper RGB among CN-strong stars. This decrease in the product
   of CxN may indicate that carbon-to-nitrogen conversion plus deep mixing is
   occurring within the CN-strong giants to a greater degree than in the CN-weak
   giants. These results, when interpreted with additional constraints from
   the giant branch luminosity function of M3, suggest that the C and N abundance
   pattern requires a hybrid scenario involving interior mixing within red giants
   as well as primordial abundance inhomogeneities that precede the RGB phase
   of evolution.
%K Galaxy: Globular Clusters: Individual: Messier Number: M3
%K Stars: Abundances
%K Stars: Population II

%R 2002PASP..114.1108T
%F ori/PASPv114n800 
%J-1116
%T The Dwarf Novae of Shortest Period(1).
%A Thorstensen, John R.
%I Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College,
   Hanover, NH 03755-3528; (thorstensen@dartmouth.edu)
%A Patterson, Joseph
%A Kemp, Jonathan
%I Department of Astronomy, Columbia University, 538 West 120th Street, New
   York, NY 10027; (jop@astro.columbia.edu)
%A Vennes, St\'ephane
%I Department of Mathematics, Australian National University, Canberra, ACT
   0200, Australia; (vennes@wintermute.anu.edu.au)
%B We present observations of the dwarf novae GW Lib, V844 Her, and DI
   UMa. Radial velocities of H{alpha} yield orbital periods of 0.05332+/-0.00002
   days (=76.78 minutes) for GW Lib and 0.054643+/-0.000007 days (=78.69 minutes)
   for V844 Her. Recently, the orbital period of DI UMa was found to be only
   0.054564+/-0.000002 days (=78.57 minutes) by Fried et al., so these are the
   three shortest orbital periods among dwarf novae with normal-abundance secondaries.
   GW Lib has attracted attention as a cataclysmic binary showing apparent ZZ
   Ceti type pulsations of the white dwarf primary. Its spectrum shows sharp
   Balmer emission flanked by strong, broad Balmer absorption, indicating a
   dominant contribution by white dwarf light. Analysis of the Balmer absorption
   profiles is complicated by the unknown residual accretion luminosity and
   lack of coverage of the high Balmer lines. Our best-fit model atmospheres
   are marginally hotter than the ZZ Ceti instability strip, in rough agreement
   with recent ultraviolet results from the {\em Hubble Space Telescope}. The
   spectrum and outburst behavior of GW Lib make it a near twin of WZ Sge, and
   we estimate it to have a quiescent M_V_~12. Comparison with archival data
   reveals proper motion of 65+/-12 mas.yr^-1^. The mean spectrum of V844 Her
   is typical of SU UMa dwarf novae. We detected superhumps in the 1997 May
   superoutburst with P_sh_=0.05597+/-0.00005 days. The spectrum of DI UMa appears
   normal for a dwarf nova near minimum light. These three dwarf novae have
   nearly identical short periods but completely dissimilar outburst characteristics.
   We discuss possible implications.
%K stars: binaries
%K stars: individual
%K stars: variables
%I (1) Based in part on observations obtained at the Michigan-Dartmouth-MIT
   Observatory.

%R 2002PASP..114.1117T
%F ori/PASPv114n800 
%J-1123
%T QZ Serpentis: A Dwarf Nova with a 2 Hour Orbital Period and an Anomalously
   Hot, Bright Secondary Star(1).
%A Thorstensen, John R.
%A Fenton, William H.
%I Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College,
   Hanover, NH 03755-3528; (john.thorstensen@dartmouth.edu), (w.h.fenton@dartmouth.edu)
%A Patterson, Joseph
%A Kemp, Jonathan (2)
%A Halpern, Jules
%I Department of Astronomy, Columbia University, 538 West 120th Street, New
   York, NY 10027; (jop@astro.columbia.edu), (j.kemp@jach.hawaii.edu), (jules@astro.columbia.edu)
%A Baraffe, Isabelle
%I \'Ecole Normale Sup\'erieure, 69364 Lyon Cedex 07, France; (ibaraffe@ens-lyon.fr)
%B We present spectroscopy and time-series photometry of the dwarf nova
   QZ Ser. The spectrum shows a rich absorption-line spectrum of type K4+/-2.
   K-type secondary stars are generally seen in dwarf novae with orbital periods
   P_orb_~6 hr, but in QZ Ser the absorption radial velocities show an obvious
   modulation [semiamplitude 207(5) km.s^-1^] at P_orb_=119.752(2) minutes,
   much shorter than typical for such a relatively warm and prominent secondary
   spectrum. The H{alpha} emission-line velocity is modulated at the same period
   and roughly opposite phase. Time-series photometry shows flickering superposed
   on a modulation with two humps per orbit, consistent with ellipsoidal variation
   of the secondary's light. QZ Ser is a second example of a relatively short
   period dwarf nova with a surprisingly warm secondary. Model calculations
   suggest that the secondary is strongly enhanced in helium and had already
   undergone significant nuclear evolution when mass transfer began. Several
   sodium absorption features in the secondary spectrum are unusually strong,
   which may indicate that the present-day surface was the site of CNO-cycle
   hydrogen burning in the past.
%K Stars: Binaries: Close
%K stars: individual (QZ Serpentis)
%K stars: individual (1RXS J232953.9+062814)
%K Stars: Variables: Other
%I (1) Based in part on observations obtained at the MDM Observatory, operated
   by Dartmouth College, Columbia University, Ohio State University, and the
   University of Michigan.
%I (2) Also at Joint Astronomy Center, Hilo, HI.

%R 2002PASP..114.1124R
%F ori/PASPv114n800 
%J-1142
%T The 7.5 Magnitude Limit Sample of Bright Short-Period Binary Stars. I. How
   Many Contact Binaries Are There?(1).
%A Rucinski, Slavek M.
%I David Dunlap Observatory, University of Toronto, P.O. Box 360, Richmond Hill,
   ON L4C 4Y6, Canada; (rucinski@astro.utoronto.ca)
%B A sample of bright contact binary stars (W UMa type or EW, and related:
   with {beta} Lyr light curves, EB, and ellipsoidal, ELL--in effect, all but
   the detached, EA) to the limit of V^max^=7.5 mag is deemed to include all
   discoverable short-period (P<1 day) binaries with photometric variation larger
   than about 0.05 mag. Of the 32 systems in the final sample, 11 systems have
   been discovered by the {\em Hipparcos} satellite. The combined spatial density
   is evaluated at (1.02+/-0.24)x10^-5^ pc^-3^. The relative frequency of occurrence
   (RFO), defined in relation to the main-sequence stars, depends on the luminosity.
   An assumption of RFO=~1/500 for M_V_>+1.5 is consistent with the data, although
   the number statistics is poor with the resulting uncertainty in the spatial
   density and the RFO by a factor of about 2. The RFO rapidly decreases for
   brighter binaries to a level of 1/5000 for M_V_<+1.5 and to 1/30,000 for
   M_V_<+0.5. The high RFO of 1/130, previously determined from the deep OGLE-I
   sample of disk population W UMa type systems toward Baade's window, is inconsistent
   with and unconfirmed by the new results. Possible reasons for the large discrepancy
   are discussed. They include several observational effects but also a possibility
   of a genuine increase in the contact-binary density in the central parts
   of the Galaxy.
%K Stars: Binaries: Close
%K Stars: Binaries: Eclipsing
%K Stars: Variables: Other
%I (1) Based on data from the {\em Hipparcos} satellite mission and from
   the David Dunlap Observatory, University of Toronto.

%R 2002PASP..114.1143T
%F ori/PASPv114n800 
%J-1149
%T Rayleigh Laser Guide Star Systems: UnISIS Bow-Tie Shutter and CCD39 Wavefront
   Camera.
%A Thompson, Laird A.(1)
%A Teare, Scott W.(2)(3)
%A Crawford, Samuel L.(4)
%A Leach, Robert W.(3)(5)
%B Laser guide star systems based on Rayleigh scattering require some means
   to deal with the flash of low-altitude laser light that follows immediately
   after each laser pulse. These systems also need a fast shutter to isolate
   the high-altitude portion of the focused laser beam to make it appear starlike
   to the wavefront sensor. We describe how these tasks are accomplished with
   UnISIS, the Rayleigh laser-guided adaptive optics system at the Mount Wilson
   Observatory 2.5 m telescope. We use several methods: a 10,000 revolution
   per minute rotating disk, dichroics, a fast sweep and clear mode of the CCD
   readout electronics on a 10 {mu}s timescale, and a Pockel's cell shutter
   system. The Pockel's cell shutter would be conventional in design if the
   laser light were naturally polarized, but the UnISIS 351 nm laser is unpolarized.
   Therefore, we have designed and put into operation a dual Pockel's cell shutter
   in a unique bow-tie arrangement.
%K Atmospheric Effects
%K Instrumentation: Adaptive Optics
%K Instrumentation: Detectors
%K instrumentation: high angular resolution
%K Telescopes
%I (1) Astronomy Department, University of Illinois Urbana-Champaign, 1002
   West Green Street, Urbana, IL 61801; (thompson@astro.uiuc.edu).
%I (2) Departments of Electrical Engineering and Physics, New Mexico Tech,
   801 Leroy Place, Socorro, NM 87801; (teare@ee.nmt.edu).
%I (3) Astronomy Department, San Diego State University, San Diego, CA 92182.
%I (4) Jet Propulsion Laboratory, California Institute of Technology, 4800
   Oak Grove Drive, Pasadena, CA 91109; (slcrawford@huey.jpl.nasa.gov).
%I (5) Astronomical Research Cameras, Incorporated, San Diego State University,
   San Diego, CA 92182; (leach@astro-cam.com).

%R 2002PASP..114.1150H
%F ori/PASPv114n800 
%J-1155
%T Radio Seeing Monitor Interferometer.
%A Hiriart, David
%A Valdez, Jorge
%I Instituto de Astronom\'ia, Universidad Nacional Aut\'onoma de M\'exico, Apartado
   Postal 877, Ensenada 22830, BC, M\'exico; (hiriart@astrosen.unam.mx), (pocho@astrosen.unam.mx)
%A Zaca, Placido
%A Medina, Jos\'e L.
%I Centro de Investigaci\'on Cient\'ifica y de Educaci\'on Superior de Ensenada, Apartado
   Postal 2732, Ensenada 22830, BC, M\'exico; (placido@cicese.mx), (jmedina@cicese.mx)
%B A two-element interferometer for monitoring atmospheric phase fluctuations
   (radio seeing) is presented; this uses the unmodulated beacon signal at 11.715
   GHz from a geostationary satellite. The system measures phase differences
   on the signal received by two small antennas separated by 50 m. The system
   incorporates the best features from previous designs: a heterodyne phase-lock
   receiver and an IQ demodulator system. Phase fluctuations measured at this
   frequency may be extrapolated to millimetric and submillimetric wavelengths
   since the atmosphere is not dispersive at these frequencies. The instrument
   has been tested at the Observatory San Pedro Martir (Mexico) at 2800 m above
   sea level. The final destination of the instrument is Cerro la Negra (Mexico),
   where the Large Millimeter Telescope is under construction, at an altitude
   of 4600 m.
%K Atmospheric Effects
%K Site Testing
%K Techniques: Interferometric

%R 2002PASP..114.1156T
%F ori/PASPv114n800 
%J-1166
%T From Differential Image Motion to Seeing.
%A Tokovinin, A.
%I Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile; (atokovinin@ctio.noao.edu)
%B The theory of the differential image motion monitor (DIMM), a standard
   and widely spread method of measuring astronomical seeing, is reviewed and
   extended. More accurate coefficients for computing the Fried parameter from
   the measured variance of image motion are given. They are tested by numerical
   simulations that show that any DIMM measures Zernike tilts, not image centroids
   as generally assumed. The contribution of CCD readout noise to image motion
   variance is modeled. It can substantially bias DIMM results if left unsubtracted.
   The second most important DIMM bias comes from the used exposure time, which
   is typically not short enough to freeze image motion completely. This effect
   is studied quantitatively for real turbulence and wind profiles, and its
   correction by interlaced short and long exposures is validated. Finally,
   the influence of turbulence outer scale reduces image size in large telescopes
   by 10% or more compared to the standard theory; new formulae to compute FWHM
   and half-energy diameter of the atmospheric point-spread function that take
   into account outer scale are provided.
%K Atmospheric Effects
%K Site Testing