HUBBLE SPACE TELESCOPE

   DAILY REPORT #2605

PERIOD COVERED:  0000Z (UTC) 04/18/00 - 0000Z (UTC) 04/19/00

Daily Status Report as of 110/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 Completed FGS 8292 (Calibrating the Mass-Luminosity Relation at the 
End of the Main Sequence)

        The Fine Guidance Sensor (FGS1R) was used to make astrometric 
observations of the star GJ1245 and other nearby reference stars.  This is 
part of a study to calibrate the mass-luminosity relation for stars less 
massive than 0.2 Msun, with special emphasis on objects near the 
stellar/brown dwarf border.  The observations were completed as planned, 
and no problems were reported.

    1.2 Completed Three Sets of STIS/CCD 8437 (Dark Monitor-Part 2 C8)

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

    1.3 Completed Three Sets of WF/PC-2 8460 (Cycle 8 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 observations completed with no reported problems.

    1.4 Completed STIS/CCD 8439 (Bias Monitor-Part 2 C8)

        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 reported problems.

    1.5 Completed STIS/CCD 8228 (The Black Hole Versus Bulge Mass 
Relationship in Spiral Galaxies)

        The Space Telescope Imaging Spectrograph (CCD) was used to make 
observations of the galaxy NGC-5248 in order to study the black hole versus 
bulge mass relationship in spiral galaxies.  A wavelength calibration image 
was also taken.  The observations were executed as scheduled, and no 
anomalies were noted.

    1.6 Completed WF/PC-2 8457 (UV Earth Flats)

        The WF/PC-2 was used to obtain a series of Ultraviolet Earth 
flats.  The observations were completed with no reported problems.

    1.7 Completed WF/PC-2 8445 (WF/PC-2 Cycle 8 Earth Flats)

        The WF/PC-2 was used to make Cycle 8 Earth flat calibration 
observations.  This is to obtain sequences of earth streak flats to 
construct high quality flat fields for the WF/PC-2 filter set.  The 
observations were executed as scheduled, and no anomalies were noted.

    1.8 Completed STIS/CCD/MA1 8243 (SINS: The Supernova Intensive Study - 
Cycle 8)

        The Space Telescope Imaging Spectrograph (CCD and MA1) was used to 
make observations of supernova SN1998S.  Supernovae reveal the last stages 
of stellar evolution, create the chemical history of the Universe, energize 
the interstellar gas, and occupy the center of attention for the 
extragalactic distance scale and cosmology.  A wavelength calibration image 
was also taken.  The observations were completed as planned, and no 
problems were reported.

    1.9 Completed Three Sets of WF/PC-2 8459 (Decontaminations and 
Associated Observations Pt. 2/2)

        The WF/PC-2 was used to perform the monthly decons.  Also included 
are instrument monitors tied to decons: photometric stability check, focus 
monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, 
and UV throughput checks.  The observations were completed nominally.

    1.10 Completed STIS/CCD/MA2 8647 (Black Hole Accretion Outbursts In 
Soft X- Ray Transients)

        The Space Telescope Imaging Spectrograph (CCD and MA2) was used to 
make UV observations of soft X-ray transient {SXT} XTE-J1118 . This is part 
of an extensive multiwavelength target of opportunity campaign to monitor 
newly discovered SXTs in outburst and throughout the subsequent 
decline.  Recent work establishes that a high proportion of SXTs harbor 
black holes, so these observations provide an unrivalled opportunity to 
obtain high quality data from an accreting black hole.  UV data is a 
keystone of this multiwavelength campaign because the disk regions of 
interest radiate predominantly in the UV.  Emission lines will give the 
ability to probe the kinematics of the inner disk region.  Tthe relative 
strengths of the reprocessed X-ray flux emitted in the UV will be examined, 
and the UV flux generated by viscous heating in the accretion 
flow.  Multiwavelength observations will probe the physics of the accretion 
flow throughout the outburst.  The observations will yield detailed 
quantitative tests of the models for SXT outbursts.  The new STIS/MAMA 
capability to perform UV spectroscopy with 125 microsecond time resolution 
will be exploited.  A proven HST/RXTE echo-mapping experiment will measure 
the size of the reprocessing regions in the accretion disk, and thus probe 
morphology changes as the decline proceeds.  It is unknown what rapid UV 
variability may be found.  Recent RXTE discoveries suggest this may prove a 
rich source of information on the dynamics close to the event horizon.  The 
observations completed with no reported problems.

    1.11 Completed STIS/CCD 8474 (Coronographic Imaging of Protoplanetary 
Disks)

        The Space Telescope Imaging Spectrograph (CCD) was used to obtain 
broad-band optical coronographic imaging that will be used to search for 
circumstellar disks and indirect signatures of the presence of massive 
planets toward the nearby Herbig Ae/Be and T Tauri stars.  The observations 
completed with no reported problems.

    1.12 Completed Two Sets of STIS/CCD 8202 (Bright Quasar Close Lensing 
Search)

        The Space Telescope Imaging Spectrograph (CCD) was used to make 
observations of HCLQ1058-2 and HCLQ1537+2 as part of a second generation 
survey to search for bright lensing quasars.  With the restored PSF, new 
images will be considerably more sensitive to the presence of both close 
separation and faint lens components, and because STIS reaches two 
magnitudes fainter the PC, the new snapshot images will have much greater 
dynamic range.  The observations were executed as scheduled, and no 
anomalies were noted.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:
       Scheduled Acquisitions: 10
Successful: 10

  Scheduled Re-acquisitions:  6
Successful:  6

    2.2 FHST Updates:
Scheduled: 25
Successful: 24

        The update at 110/060131Z failed.

    2.3 Operations Notes:

        HST operations continues to be run from the Building 23 back-up 
facility.

        Using ROP SR-1A, the SSR EDAC error counter was cleared twice.

        ROP IC-1 was utilized three times to manage the MA transponder.

        Six battery pressure test modifications were executed at 109/1051Z, 
per ROP IP-01.  Then, at 109/1129Z, the Voltage/Temperature Front End 
(VTFE) curve update procedure was run as directed by ROP IP-05A.  When this 
was successful, the new Trim Relay Software Charge Control (TRSWCC) flight 
software was uplinked at 109/1422Z.  Using ROP IP-5B, the trim relay charge 
control procedure (with a failed K61 relay) was performed at 
109/1425Z.  Telemetry diagnostics for monitoring the new flight software 
load were installed at 109/1428Z, and at 109/1433Z, the Servicing Mission 
recovery SPC load was patched.  Limits for parameters involved in 
TRSWCC/VTFE were then adjusted.

        An HST486 table dump was performed at 109/2024Z, per ROP DF-1A.

3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of normal science observations and calibrations.

/CAW