HUBBLE SPACE TELESCOPE

  DAILY REPORT #2850

PERIOD COVERED:  0000Z (UTC) 04/12/01 - 0000Z (UTC) 04/13/01

Daily Status Report as of 103/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 Completed Two Sets of WF/PC-2 8827 (Cycle 9 Supplemental Darks pt2/3)

        The WF/PC-2 was used to obtain three dark frames every day to 
provide data for monitoring and characterizing the evolution of hot 
pixels.  The proposal completed nominally.

    1.2 Completed STIS/CCD 8865 (Bias Monitor-Part 2)

        The Space Telescope Imaging Spectrograph (CCD) was used to monitor 
the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at 
gain = 4, to build up high-S/N superbiases and track the evolution of hot 
columns.  The proposal completed with no anomalous activity.

    1.3 Completed WF/PC-2 8712 (The Wind Accretion Wake In A Detached 
Binary System)

        The WF/PC-2 was used to observe RW Hya {= HD 117970}, the only 
known detached binary system, where direct observational evidence for wind 
accretion onto a white dwarf is found.  UV
observations will enable the investigator to advance knowledge in a field 
which has for long had to remain a theoretical subject.  RW Hya is an 
eclipsing system containing a mass-losing M-giant and a hot white dwarf on 
circular orbits {370 days}.  The observation completed with no reported 
problems.

    1.4 Completed WF/PC-2 9244 (POMS Test Proposal: WFII Parallel Archive 
Proposal Continuation)

        The WF/PC-2 was used to perform a generic target version of the 
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 Group.  The observations completed with no anomalous 
activity.

    1.5 Completed STIS/CCD 8864 (CCD Dark Monitor-Part 2)

        The Space Telescope Imaging Spectrograph (CCD) was used to monitor 
the darks for the CCD.  The proposal completed nominally.

    1.6 Completed Six Sets of WF/PC-2 8699 (The Origin of Short-Period Comets)

        The WF/PC-2 was used to detect and characterize cometary nuclei in 
order to determine the basic physical properties of a large fraction of the 
population of short-period comets.  By acquiring statistically significant 
data, we can study the origin of this family of comets and test the 
hypothesis that they are collisional fragments from the Kuiper Belt 
Objects.  The observations completed with no reported problems.

    1.7 Completed Two Sets of STIS/MA1 8860 (MAMA Fold Distribution)

        The Space Telescope Imaging Spectrograph (MA1) was used to monitor 
the performance of MAMA microchannel plates using a MAMA fold analysis 
procedure.  The fold analysis provides a measurement of the distribution of 
charge cloud sizes incident upon the anode giving some measure of changes 
in the pulse-height distribution of the MCP and, therefore, MCP 
gain.  There were no problems.

    1.8 Completed STIS/MA1 8843 (Cycle 9 MAMA Dark Measurements)

        The Space Telescope Imaging Spectrograph (MA1) was used to perform 
the routine monitoring of the MAMA detector dark noise.  The proposal 
completed nominally.

    1.9 Completed Two Sets of STIS/MA2 8863 (NUV-MAMA Cycle 9 Flats)

        The Space Telescope Imaging Spectrograph (MA2) was used to obtain 
NUV-MAMA observations of the internal Deuterium lamp to construct an NUV 
flat applicable to all NUV modes.  There were no reported problems.

    1.10 Completed WF/PC-2 8634 (Atmospheric Variability on Uranus and Neptune)

        The WF/PC-2 was used to obtain snapshot observations of Uranus and 
Neptune to monitor changes in their atmospheres on time scales of months to 
years.  Uranus is rapidly approaching equinox in 2007, with another 4 
degrees of latitude in the northern hemisphere becoming visible every 
year.  Recent HST images during this unique epoch have revealed: {i} 
strongly wavelength-dependent latitudinal structure, {ii} the presence of 
numerous visible-wavelength cloud features in the northern hemisphere, and, 
{iii} in the near-IR, discrete features northward of 25degrees N that have 
the highest contrast ever seen for a Uranian cloud.  Long-term ground- 
based observations show seasonal brightness changes whose origins are not 
well understood.  Recent IR images of Neptune obtained using adaptive 
optics on the Keck Telescope indicate that a new "Bright Companion" type of 
feature has recently appeared in the southern hemisphere.  Snapshot 
observations of these two dynamic planets can supply context in which to 
discern the nature of long-term changes in their latitudinal atmospheric 
bands and to track the appearance, movement, and disappearance of discrete 
albedo features.  There were no reported problems.

    1.11 Completed STIS/MA1 8862 (FUV-MAMA Cycle 9 Flats)

        The Space Telescope Imaging Spectrograph (MA1) was used to obtain 
FUV-MAMA observations of the internal Krypton lamp to construct an FUV flat 
applicable to all FUV modes.  No problems were encountered.

    1.12 Completed WF/PC-2 8816 (Cycle 9 UV Earthflats)

        The WF/PC-2 was used to obtain sequences of Earth streak flats to 
improve the quality of pipeline flat fields for the WFPC2 UV filter set and 
in order to monitor flat field stability.  There were no reported problems.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:
       Scheduled Acquisitions: 14
Successful: 12

        Per HSTAR 8162, the acquisition at 103/032029Z failed after four 
attempts to achieve finelock when the search radius limit was exceeded on 
FGS-3.  Two proposals, each occurring during the period of the next report, 
were affected: WF/PC 8699 and STIS 8863.

        Per HSTAR 8163, the acquisition at 103/045707Z when the search 
radius limit was exceeded on both FGS-1 and FGS-3.  Two proposals, each 
occurring during the period of the next report, were affected: WF/PC 8699 
and STIS 8862.
  Scheduled Re-acquisitions:  0
Successful:  0

    2.2 FHST Updates:
Scheduled: 26
Successful: 26

    2.3 Operations Notes:

        Using ROP DF-18A, the CCS engineering status buffer (ESB) limits 
were adjusted four times.  The ESB was also dumped and cleared four times, 
using the same ROP.

        The SSR EDAC error counter was cleared at 102/1444Z per ROP SR-1A.

        Operations personnel supported GSFC Internal Simulation #7 (EVA-3) 
yesterday, in the STOC area, from 8:15 a.m. until 12:30 p.m.

3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of normal science observations and calibrations.

/CAW