HUBBLE SPACE TELESCOPE

   DAILY REPORT #2898

PERIOD COVERED:  0000Z (UTC) 06/20/01 - 0000Z (UTC) 06/21/01

Daily Status Report as of 172/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 Completed Three Sets of WF/PC-2 8828 (Cycle 9 Supplemental Darks pt3/3)

        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 with no reported problems.

    1.2 Completed Two Sets of WF/PC-2 8592 (Pixel Microlensing of M87)

        The WF/PC-2 was used to undertake a pixel microlensing study of M87 
in order to: 1} probe the lower end of the M87 IMF via star-star lensing, 
2} possibly obtain the first evidence of Massive Compact Objects (MACHOs) 
in the halo of a galaxy other than our own, and 3} search for intracluster 
MACHOs.  The proposal completed nominally.

    1.3 Completed Two Sets of WF/PC-2 8601 (A Snapshot Survey of Probable 
Nearby Galaxies)

        The WF/PC-2 was used to continue the very successful snapshot 
survey in order to use the high spatial resolution of HST to determine 
whether selected galaxies are nearby on the basis of resolution into stars, 
and the magnitudes and colors of the brightest stars.  There were no 
reported problems.

    1.4 Completed WF/PC-2 9140 (Is GRO J1655-40 a Runaway Black Hole?)

        The WF/PC-2 was used to examine the formation of black holes which 
is one of the most intriguing problems in astronomy.  In the case of 
stellar-mass black holes, several theories propose that they are born with 
large space velocities.  To test this idea we wish to determine the space 
velocity of X-ray Nova Scorpii 1994 {GRO J16155-40}, which is one of the 
best black hole candidates of stellar mass, and a source of jets with 
apparent superluminal motions.  This intriguing object is located ~eq 
2.5^degrees above the galactic plane and the center of mass of the system 
is known to be moving with a large anomalous radial velocity with respect 
to the Local Standard of Rest.  Since GRO J16155-40 has already been imaged 
with the WFPC2 in 1995, one more image with the same instrumental set-up 
could allow us to measure its expected proper motion with an accuracy of a 
few percent.  This observation may provide the first unambiguous evidence 
for a black hole formed in the Milky Way that is migrating into 
intergalactic space.

    1.5 Completed WF/PC-2 8177 (Investigating Type Ia Supernovae and an 
Accelerating Universe)

        The WF/PC-2 was used to obtain rest frame U and B photometry for 
four z~ 0.85 Supernova (SN) Ia.  These observations will be coupled to 
ground-based rest frame V photometry and spectra.  These data, combined 
with previous samples, will extend the D_L vs. z diagram for SN Ia to 
z~0.85, and allow us to discriminate the redshift dependence of supernova 
magnitudes in an accelerating Universe from that expected to result from 
systematic effects such as age of the stellar population, chemical 
evolution, a drift in the properties of dust, and weak gravitational 
lensing.  The proposal completed with no reported problems.

    1.6 Completed WF/PC-2 9086 (Investigating the Formation History of 
Spiral Galaxy Halos)

        The WF/PC-2 was used to make observations in order to constrain the 
origin of spiral galaxy halos by studying stellar populations near the tip 
of the red giant branch.  This will be the first systematic study of this 
population in external galaxies and will quadruple the sample of normal 
spiral galaxies for which the halo metallicity distribution function is 
measured.  This larger sample will permit study of the relationship between 
the bulge, disk, and halo components and between halos and globular 
systems.  Such correlations will in turn provide indications as to whether 
the halo, bulge, and globular cluster systems built up nearly 
simultaneously in the early universe or were accreted over time through 
different kinds of merging events.  The proposal completed nominally.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:
       Scheduled Acquisitions:  5
Successful:  5

  Scheduled Re-acquisitions: 10
Successful: 10

    2.2 FHST Updates:
Scheduled: 10
Successful: 10

    2.3 Operations Notes:

        The STIS instrument remains in safe mode.

        The SSR EDAC error counter was cleared once per ROP SR-1A.

        Operations personnel participated in GSFC Internal Simulation #9 
(EVA-3/PCU) yesterday from 8:00 a.m. until just past midnight.

3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of normal science observations and calibrations.

/CAW