Status Report

Hubble Space Telescope Daily Report #2727 10/13/00

By SpaceRef Editor
October 13, 2000
Filed under

PERIOD COVERED:  0000Z (UTC) 10/12/00 – 0000Z (UTC) 10/13/00
Daily Status Report as of 287/0000Z
    1.1 Completed WF/PC-2 8599 (A Census of Nuclear Star Clusters in Late-Type Spiral Galaxies)
        The WF/PC-2 was used to conduct an I-band snapshot survey of a well-defined sample of nearby, face-on spiral galaxies of type Scd or later.  The proposal completed nominally.
    1.2 Completed Five Sets of STIS/CCD 8562 (Probing the Large Scale Structure: Cosmic Shear Observations)
        The Space Telescope Imaging Spectrograph (CCD) was used to probe the distortion of light bundles from distant galaxies, looking at the statistical properties of the intervening inhomogeneous {dark} matter distribution.  The proposal completed nominally.
    1.3 Completed Two Sets of STIS/CCD 8837 (CCD Dark Monitor-Part 1)
        The Space Telescope Imaging Spectrograph (CCD) was used to monitor the darks.  The proposal completed with no reported problems.
    1.4 Completed WF/PC-2 8701 (Multiplicity among Very-Low Mass Stars and Brown Dwarfs in Alpha Persei and the Pleiades)
        The WF/PC-2 was used to observe open clusters which provide excellent hunting grounds for brown dwarf {BD} searches.  The AlphaPer and Pleiades clusters are young, nearby and have low extinction.  They are considered to be the best-suited places to study the Substellar Mass.  A dozen of cool faint AlphaPer and Pleiades members have been confirmed as “bona-fide” BDs with the lithium test.  By comparison with those, about 60 very good cluster BD candidates are currently known.  The Pleiades SMF obtained using the most recent deep large CCD surveys indicates that BDs are quite numerous but do not make a significant contribution to the total cluster mass.  The observations completed with no reported problems.
    1.5 Completed WF/PC-2/STIS/CCD 8559 (The Role of Dark Matter in Cluster Formation and Galaxy Evolution)
        The WF/PC-2 and the Space Telescope Imaging Spectrograph (CCD) were used to observe the outer regions of massive clusters that represent transitional areas of great cosmological importance where field galaxies encounter the steep potential wells of dark matter and baryonic hot gas.  Little is known about either the dark matter profile at large radii or the morphological properties of infalling galaxies at those redshifts where strong evolution is observed in the cluster cores.  The proposal completed normally, with no reported problems.
    1.6 Completed WF/PC-2 8581 (A Search For Low-Mass Companions To Ultracool Dwarfs)
        The WF/PC-2 was used to search for very low-mass {VLM} companions to a complete sample of 120 late-M and L dwarfs, drawn mainly from the 2MASS and SDSS surveys.  The primary goal is to determine the multiplicity of M < 0.1 M_odot dwarfs.  In particular, we aim to identify binary systems suitable for long-term astrometric monitoring and mass measurement, and systems with cool, sub-1000K companions.  The proposal completed with no reported problems.
    1.7 Completed Two Sets of STIS/CCD/MA2 8695 (The Nature and Distribution of O VI Absorbers in the Vicinity of Galaxies)
        The Space Telescope Imaging Spectrograph (CCD and MA2) was used to study PG0953+415 with the E140M echelle mode to substantially improve the statistical base of observed O VI absorbers {including weak lines} for comparison with the cosmological models and to constrain the physical conditions and abundances in these systems and their relationships with galaxies.  With these observations we will {1} measure the number of O VI absorbers per unit redshift {dN/dz} with a limiting equivalent width of W_Lambda ~25 mAngstrom , {2} examine whether the O VI absorption arises in photoionized, collisionally ionized, or multiphase gas, {3} estimate the absorber metallicities, and {4} study the dependence of the absorber properties on the proximity of luminous galaxies.  The observations completed nominally.
    1.8 Completed Three Sets of WF/PC-2 8805 (POMS Test Proposal: WFII Parallel Archive Proposal Continuation)
        The WF/PC-2 was used to perform a generic target version of the WFPC2 Archival Pure Parallel program.  The program will be used to take parallel images of random areas of the sky, following the recommendations of the Parallels Working.  The proposal completed with no reported problems.
    1.9 Completed FGS/1R 8832 (Long Term Monitoring in Position Mode)
        Fine Guidance Sensor-!R was used to observe the relative positions of stars in a standard cluster at a fixed telescope pointing and orientation coordinates.  The evolution of rhoA and kA were monitored and calibrated to preserve the astrometric integrity of the FGS.  It is well known for our experience with FGS3, and later with FGS1r, that an FGS experiences long term evolution, presumably due to disorption of water from the instrument’s graphite epoxy composites.  This manifests principally as a change in the plate scale and secondarily as a change in the
distortions.  The proposal completed nominally, with no reported problems.
    1.10 Completed STIS/CCD 8838 (Bias Monitor – Part 1)
        The Space Telescope Imaging Spectrograph (CCD) was used to monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.  The proposal completed nominally.
    1.11 Completed WF/PC-2 7407 (Continuation of Temporal Monitoring of the Crab Synchrotron Nebula)
        The WF/PC-2 was used to observe the synchrotron nebula surrounding the Crab pulsar that has been the subject of intensive study for decades.  It is generally accepted that the structure and activity in this region are due to wave phenomena near the termination shock of the pulsar wind, observations of which hold unique promise of leading to more complete models of the pulsar and its magnetosphere.  Unfortunately, this promise has not been fulfilled, largely because of the low spatial resolution and uneven temporal coverage of existing studies.  Recent WF/PC-2 observations of the Crab synchrotron nebula offer new hope in this quest.  These data, which reach the natural size scale defined by the Larmor radius of energetic electrons, resolve the majority of the the known features in the Crab.  For the first time it is possible to reliably establish the physical conditions {e.g., emissivities, equipartition fields, and pressures} of features associated with the wind and its termination shock.  The observation completed as planned.
    1.12 Completed WF/PC-2 8826 (Cycle 9 Supplemental Darks pt 1)
        The WF/PC-2 was used to perform a T dark calibration program that obtains three dark frames every day in order to provide data for monitoring and characterizing the evolution of hot pixels.  There were no reported anomalies.
    2.1 Guide Star Acquisitions:
      Scheduled Acquisitions: 8
Successful: 8
  Scheduled Re-acquisitions: 7
Successful: 7
    2.2 FHST Updates:
Scheduled: 20
Successful: 20
    2.3 Operations Notes:
        At 286/1235Z, the K10 bypass relay was closed and the flight software was re-configured to reflect the changes.
        The NSSC-1 status buffer was dumped and reset at 286/1506Z, using ROP NS-3.
        The SSR EDAC error counter was cleared at 286/1511Z per ROP SR-1A.
        Continuation of normal science observations and calibrations.

SpaceRef staff editor.