HUBBLE SPACE TELESCOPE

   DAILY REPORT #2835

PERIOD COVERED:  0000Z (UTC) 03/22/01 - 0000Z (UTC) 03/23/01

Daily Status Report as of 082/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 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.

    1.2 Completed Four Sets of STIS/CCD 9248 (Probing the Large Scale 
Structure: Cosmic Shear Observations)

        The Space Telescope Imaging Spectrograph (CCD) was used to measure 
the distortion of light bundles from distant galaxies that probe the 
statistical properties of the intervening inhomogeneous {dark} matter 
distribution.  Its tidal gravitational field distorts the observable image 
shapes thereby causing a coherent ellipticity pattern {Cosmic Shear}.  As 
described 2.1 and HSTAR 8130, the acquisition for the first iteration of 
this proposal failed, affecting one observation.  Otherwise, the 
observations completed nominally.

    1.3 Completed Two Sets of WF/PC-2 8698 (Identification of the Galaxy's 
Missing Mass)

         The WF/PC-2 was used to observe the nature of dark matter that is 
one of the key astrophysical questions of the day.  The existence of dark 
matter and its dynamical dominance in the outer parts of our Galaxy and 
spiral galaxies with flat rotation curves is well established.  The MACHO 
project has identified ~half of the Milky Way's dark matter with stellar 
objects of ~0.5 M_sun, probably white dwarfs.  But the location of the 
microlensing in the halo is disputed.  Several have detected two candidate 
halo white dwarfs of L/L_sun ~ 10^-5 in the Hubble Deep Field with 25 +/- 5 
mas/year proper motions.  As described 2.1 and HSTAR 8130, the acquisition 
for the first iteration of this proposal failed, affecting one 
observation.  Otherwise, the observations completed with no further 
reported problems.

    1.4 Completed Five 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.  As described 2.1 and HSTAR 8130, the acquisition for the first two 
iterations of this proposal failed, affecting one observation in each 
iteration.  Otherwise, the proposal completed nominally.

    1.5 Completed STIS/CCD/MA1/MA2 8595 (Does the D/H Ratio Vary in Local 
Interstellar Gas?)

        The Space Telescope Imaging Spectrograph (CCD, MA1, and MA2) was 
used to take measurements of the D/H ratio in the Local Interstellar Cloud 
{LIC} that are consistent with 1.5 +/- 0.1 X 10^-5, while for other clouds 
within ~ 100 pc, the measurement uncertainties are larger.  Two target 
white dwarfs {WDs}, HZ 43 and GD 153, are chosen because EUVE data show low 
HI column densities, thereby reducing the probabilities of multiple 
velocity components and saturation of the DI line.  The WDs have pure-H 
atmospheres, so contamination of the interstellar lines by photospheric 
metal lines is not an issue.  The measurements completed with no reported 
problems.

    1.6 Completed Four Sets of 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.

    1.7 Completed WF/PC-2 8824 (Decontaminations and Associated 
Observations Pt. 3/4)

        The WF/PC-2 was used for the monthly WFPC2 decons.  Also included 
are instrument monitors tied to decons: photometric stability check, focus 
monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, 
UV throughput check, VISFLAT sweep, and internal UV flat check.  There were 
no reported problems.

    1.8 Completed Three Sets of 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.

    1.9 Completed Two Sets of 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.

    1.10 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.

    1.11 Completed FGS/1R 8833 (Long Term Stability of FGS1r in Transfer Mode)

        Fine Guidance Sensor #1R was used to monitor the temporal stabilty 
of the FGSr1 S-curves.  During its first 1.5 years onboard HST FGS1r 
demonstrated evolution of its S-curves, both in fringe visibility 
{amplitude} and fringe morphology.  By June of 1998 the fringes appeared to 
have stabilized.  The articulated mirror assembly, or AMA, was adjusted in 
Sept. 1998 to re-optimize the instrument's interferometric response.  The 
S-curves were monitored for the remainder of cycles 7 and 8.  Remarkably, 
no changes larger that typical "observational noise" {induced by spacecraft 
jitter} have been seen in either the X or Y axis S-curves since September 
1998.  Until now the monitoring of FGS1r was carried out by periodically 
observing the standard star UPGREN69 at the center of the FGS1r FOV in 
Transfer mode with both the F583W filter and the 2/3 PUPIL stop.  This 
proposal marks a departure from that approach.  Four standard stars of 
different B-V colors from the FGS1r Transfer Mode calibration library will 
be observed once each.  There was no anomalous activity.

    1.12 Completed STIS/CCD 8236 (Black Holes and Gas Disks in a Complete 
Sample of Radio-Loud Ellipticals - II: Kinematics)

        The Space Telescope Imaging Spectrograph (CCD) was used to make 
observations of the radio-loud elliptical galaxy NGC-4261.  From these 
observations we will measure the black hole masses, determine the nature, 
kinematics, and structure of the central gas disks and obtain a modeled 
upper limit to their mass accretion rates.  A wavelength calibration image 
was also taken.  The observations were completed as planned, and no 
problems were reported.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:
       Scheduled Acquisitions:  7
Successful:  7

        Per HSTAR 8130, the acquisition scheduled for 081/023037Z filed 
when trackers 2 and 3 exceeded the search radius limit.  The above 
statistics were not affected since it occurred in the previous operations 
reporting day.  Proposals described in 1.2, 1.3, and 1.3 were affected:
  Scheduled Re-acquisitions:  8
Successful:  8

    2.2 FHST Updates:
Scheduled: 17
Successful: 17

    2.3 Operations Notes:

        The SSR EDAC error counter was cleared twice, using ROP SR-1A.

        The engineering status buffer limits were adjusted on three 
occasions per ROP DF-18A.

        TTRs were written for two required re-transmits: at 082/0430Z 
during a NSSC-1 load and at 082/0746Z during a 486 load.

        SI C&DH errors were reset at 082/0436Z as directed by ROP NS-5.

3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of normal science observations and calibrations.

/CAW