Hubble Space Telescope Daily Report #2908 6 Jul 2001

HUBBLE SPACE TELESCOPE

DAILY REPORT #2908

PERIOD COVERED: 0000Z (UTC) 07/05/01 – 0000Z (UTC) 07/06/01

Daily Status Report as of 187/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

1.1 Completed Five Sets of WF/PC-2 9042 (An Archive To Detect The
Progenitors Of Massive, Core-Collapse Supernovae)

The WF/PC-s was used to search for supernovae which have massive
star progenitors.
The already extensive HST archive and high-resolution ground-based images
of galaxies within ~20 Mpc enables us to resolve and quantify their
individual bright stellar content. As massive, evolved stars are the most
luminous single objects in a galaxy, the progenitors of core-collapse
supernovae should be directly detectable on pre-explosion images. One Type
II progenitor has been observed this year, and the investigators have
proposed a short, companion WFPC2 proposal to confirm this candidate and
identify a second. The observations completed nominally.

1.2 Completed FGS/1 9168 (The Distances to AM CVn Stars)

Fine Guidance Sensor (FGS) #1 was used to determine the parallaxes
and proper motions of the five brightest of the seven known AM CVn systems
using the HST FGSs. AM CVn systems are binaries where mass is transferred
from a completely hydrogen-deficient, degenerate mass donor to a white
dwarf primary through a helium accretion disk. A better understanding of
these systems is crucial for a number of reasons: (1) to study the late
stages of binary evolution, (2) to study the effect of chemical composition
on the physics of accretion discs, (3) to estimate their contribution to
the Supernovae Ia rate, and (4) to estimate their contribution to the
gravitational radiation background. All observations completed with no
reported problems.

1.3 Completed Two 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.

1.4 Completed FGS/1 9097 (The Mass-Luminosity Relationship for High
Mass Stars: Resolving the `Mass Discrepancy’ with HST)

Fine Guidance Sensor #1 was used to investigate the mass-luminosity
relation for very low mass stars. This relationship is well determined for
intermediate-mass stars. The observations completed with no reported
problems.

1.5 Completed WF/PC-2 8574 (Proper Motions in Baade’s Window)

The WF/PC-2 was used to obtain third epoch observations of a rich
field in Baade’s Window. In just three orbits, very accurate proper
motions will be measured for ~ 13, 000 Galactic bulge stars down to V =
23. Such a large number of stars, combined with color information, a
relatively long baseline, and the high spatial resolution of HST, will
enable an unprecedented opportunity to model the structure and dynamics of
the Galactic bulge and bar populations. In addition, by selecting stars on
the basis of their proper motions, the investigator will be able to refine
the color-magnitude distributions of stars in the bulge and the bar, and
thus the corresponding initial mass functions and chemical enrichment
histories. No anomalous activity was noted.

1.6 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.

1.7 Completed WF/PC-2 8820 (Wavelength Stability of Narrow Band and
Linear Ramp Filters)

The WF/PC-2 was used to verify the mapping of wavelength as a
function of CCD position on linear ramp filters and to check for changes in
central wavelengths of the narrow band filters. The proposal completed
nominally.

1.8 Completed Two Sets of WF/PC-2 9104 (A Study of Proplyds and a
Protostellar Condensation at the Center of M20)

The WF/PC-2 was used to observe the Trifid nebula {M20} that is a
well-known prominent optical HII region trisected by bands of obscuring
dust lanes and excited by an O7.5 star HD 164492A. Our recent study of
near-IR ground-based observations of this region at J, H, K and L show all
seven components of HD 164492 {A to G} identified optically. Our
sub-arcsecond radio continuum VLA and ground- based observations of M20
also show free-free emission from three stellar sources {B, C and D} and a
bright rim outlining a protostellar condensation {TC1} lying close to the
O7V star {HD 164492A} at the center of the nebula. Based on a number of
strong arguments, these stars have disks associated with them and their
envelopes are photoionized externally by the UV radiation from the hot
central star, HD 164492A. These proposed WFPC2 observations are intended
to search for neutral protoplanetary disks “proplyds”, to study the
optically bright rim of ionized gas associated with TC1 for signs of star
formation, and to make a detailed subarcsecond determination of extinction
toward the dust lanes of M20 using HAlpha and 6cm data. There were no
reported problems.

1.9 Completed WF/PC-2 9162 (Local Galaxy Flows and the Local Mass
Density)

The WF/PC-2 was used to investigate dark matter which is the main
constituent of the universe. It is not know how much there is, how it is
distributed, or its composition. Galaxies contain dark matter that extends
many tens of kiloparsecs from their centers, but we do not know the
limits. The distribution of total mass in the universe can be determined
by modelling the orbits galaxies have followed. The proposal completed
with no reported problems.

1.10 Completed Two Sets of WF/PC-2 9124 (Mid-UV SNAPSHOT Survey of
Nearby Irregulars: Galaxy Structure and Evolution Benchmark)

The WF/PC-2 was used to investigate the relation between star
formation and the global physical characteristics of galaxies to interpret
the morphologies of distant galaxies in terms of their evolutionary
status. Distant galaxies are primarily observed in their rest frame
mid-ultraviolet. They resemble nearby late-type galaxies, but are they
really physically similar classes of objects? It is proposed to address
this question through a SNAPSHOT survey in the 2 mid-UV filter F300W of 98
nearby late-type, irregular and peculiar galaxies. No problems were
reported.

1.11 Completed Two Sets of WF/PC-2 8682 (A Snapshot Study of
0bservational Cosmology)

The WF/PC-2 was used to examine the observational constraints on
the cosmic star formation history that is currently among the most active
fields in observational cosmology. The most widely used tracer of the
co-moving volume-averaged star formation rate {SFR} is the UV luminosity
density, which early results found to peak at z~1- 2. The apparent
identification of the primary epoch of metal production and star formation
in the Universe led to intense theoretical and observational
interest. Nevertheless, and remarkably for such a fundamental observation,
little is known about the history of star formation in the Universe beyond
its global average. There were no reported anomalies.

1.12 Completed Two 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.

2.0 FLIGHT OPERATIONS SUMMARY:

2.1 Guide Star Acquisitions:

Scheduled Acquisitions: 19

Successful: 19

Scheduled Re-acquisitions: 2

Successful: 2

2.2 FHST Updates:

Scheduled: 29

Successful: 27

Per HSTAR 8257, the full maneuver updates scheduled for 186/214711Z
and at 186/214956Z failed due to errors for both trackers 1 and 3. The
subsequent acquisition, however, was successful.

2.3 Operations Notes:

The Space Telescope Imaging Spectrograph (STIS) instrument is in
boot mode, having been commanded there on day 184. All 257 segments of the
STIS Side 2 flight software (FSW) were successfully uplinked and verified
by 186/1454Z. The STIS EEPROM post-installation dump was verified against
the configured image by FSW personnel. There will be a Flight Readiness
Review this morning, with the planned commanding to take STIS to operate
mode scheduled for approximately 187/1442Z.

The SSE EDAC error counter was cleared four times per ROP SR-1A.

Using ROP DF-18A, the 486 engineering status buffer limits were
adjusted twice.

As directed by ROP IC-2, SSA transmitter 2 was turned on at
186/1355Z and turned off at 186/1418Z. Later, the same transmitter was
turned on at 186/1532Z and turned off at 186/1552Z.

3.0 SIGNIFICANT FORTHCOMING EVENTS:

Resumption of STIS science operation (on Side 2) next week.

Continuation of normal science observations and calibrations.