Hubble Space Telescope Daily Report #3096 – 17 Apr 2002

HUBBLE SPACE TELESCOPE

DAILY REPORT #3096

PERIOD COVERED: 0000Z (UTC) 04/16/02 – 0000Z (UTC) 04/17/02

Daily Status Report as of 107/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

1.1 Completed Two Sets of STIS/CCD 8902 (Dark Monitor-Part 2)

The Space Telescope Imaging Spectrograph (CCD) was used to monitor
the darks. No problems were reported.

1.2 Completed Five Sets of ACS/WFC/HRC 8947 (Weekly Test)

The Advanced Camera for Surveys (WFC and HRC) was used to perform
basic tests to monitor, the read noise, the development of hot pixels and
test for any source of noise in ACS CCD detectors. This program will be
executed at least once a day for the entire lifetime of ACS. There were no
problems reported.

1.3 Completed Three Sets of WF/PC-2 8937 (Cycle 9 Supplemental Darks pt2/3)

The WF/PC-2 was used obtain three dark frames every day to provide
data for monitoring and characterizing the evolution of hot pixels. No
problems were encountered.

1.4 Completed FGS/1 9234 (Calibrating the Mass-Luminosity Relation at
the End of the Main Sequence)

Fine Guidance Sensor #1 was used 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 proposal completed with
no reported errors.

1.5 Completed STIS/CCD 8904 (Bias Monitor-Part 2)

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

1.6 Completed ACS/WFC 9020 (Preliminary ACS Sensitivity)

The Advanced Camera for Surveys (HFC) was used to observe a
spectrophotometric standard star through each filter of each camera to
assess the sensitivity of the instrument. The star is placed at the center
of the aperture, and two images are taken through each filter. There were
no reported problems.

1.7 Completed Two Sets of STIS/MA1/MA2 8920 (Cycle 10 MAMA Dark
Measurements)

The Space Telescope Imaging Spectrograph (MA1 and MA2) was used to
perform the routine monitoring of the MAMA detector dark noise, and is the
primary means of checking on health of the MAMA detectors systems through
frequent monitoring of the background count rate. The proposal completed
with no reported anomalous activity.

1.8 Completed STIS/CCD/MA2 9051 (Identifying Damped Lyman-alpha
Galaxies at z~1)

The Space Telescope Imaging Spectrograph (CCD and MA2) was used to
look for damped Lyman-alpha absorption systems that contain the bulk of the
neutral gas in the Universe in the redshift range z = 0.5 – 5, yet the
nature of the galaxies responsible for the absorption is not well
understood. Only recently have observers found more than a handful of
damped absorbers at redshifts z < 1.5. Using the FIRST Bright Quasar Survey {FBQS}, with over a 1000 quasars, the proposers have undertaken a survey to build a complete picture of he nature of the galaxies responsible for damped Lyman-alpha absorption systems at z~1 and to double the sample size at this redshift. No problems were encountered.

1.9 Completed STIS/MA2 9573 (NUV-MAMA Daily Dark Monitor)

The Space Telescope Imaging Spectrograph (MA2) was used to perform
daily monitoring of the NUV MAMA detector dark noise in order to monitor
the effects of thermal changes on the NUV dark rate. No problems occurred.

1.10 Completed STIS/CCD 9110 (A Search for Kuiper Belt Object Satellites)

The Space Telescope Imaging Spectrograph (CCD) was used to
investigate whether the large number of collisions thought to have taken
place in the primordial Kuiper belt suggest that many Kuiper belt objects
{KBOs} could have suffered binary-forming collisions similar to that which
formed the Pluto — Charon binary. Detection of such KBO satellites would
allow measurement of KBO masses, would help to understand the past
collisional environment of the Kuiper belt, and would give a context to the
otherwise unique-seeming formation of the Pluto — Charon binary. The
proposal completed with no reported problems.

1.11 Completed STIS/CCD/MA2 8919 (MAMA Sensitivity and Focus Monitor C10)

The Space Telescope Imaging Spectrograph (CCD and MA2) was used to
monitor the sensitivity of each MAMA grating mode to detect any change due
to contamination or other causes, and also to monitor the STIS focus in a
spectroscopic and an imaging mode. All observations were successful.

1.12 Completed STIS/CCD/MA1 9184 (A Survey for Missing Baryons in
Highly Ionized Intergalactic Gas at Low Redshift)

The Space Telescope Imaging Spectrograph (CCD and MA1) was used to
observe six additional low-z QSOs with the STIS FUV E140M echelle mode {7
km s^-1 resolution}. Combined with archival data, this will increase the
sample redshift path by a factor of ~7 compared to the published
data. With the echelle data, we will {1} measure the number of O VI
absorbers per unit redshift {dN/dz} and their minimum cosmological mass
density with a limiting equivalent width of W_Lambda ~50 mAngstrom , {2}
examine whether the O VI absorption arises in photoionized, collisionally
ionized, or multiphase gas, and {3} study the dependence of the O VI system
properties on environment. In addition to testing this prediction
regarding the location of the missing baryons, the data will have
applications to many other topics such as low-z LyAlpha absorbers and the
physical properties and abundances of gas in the Milky Way halo. There was
no reported anomalous behavior.

1.13 Completed STIS/MA1 8921 (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. All
observations completed normally.

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The following scheduled proposal did not execute due to the BALL decision
to delay the ACS high voltage on commanding:

ACS/SBC 9008 (MAMA Initial Turn-on and Anomalous Recovery
Procedure)

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The following proposals were not successful due to the Gyro #3 event when
all subsequent acquisitions/re-acquisitions failed:

WF/PC-2 8950 (SM3B Cool Down, Contamination Monitor, and
Focus Check)

Two Sets of STIS/CCD 9131 (Imaging the Host Galaxies of High
Redshift Type
Ia Supernovae)

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2.0 FLIGHT OPERATIONS SUMMARY:

2.1 Guide Star Acquisitions:

Scheduled Acquisitions: 9

Successful: 2

Scheduled Re-acquisitions: 8

Successful: 3

Per HSTAR 8610, the acquisition at 106/162546Z failed to RGA
control. All subsequent acquisitions/re-acquisitions also failed. The
gyro #3 motor current event (HSTAR 8609) may have contributed to the
failures (see 2.3).

2.2 FHST Updates:

Scheduled: 14

Successful: 13

The roll delay update at 107/071956Z failed when the error box
results showed a value for QDVERRV0 of 356.130. This is related to the
Gyro #3 event. HSTAR 8611 was written.

2.3 Operations Notes:

Using ROP DR-18A, the 486 engineering status buffer limits were
adjusted twelve times.

Per HSTAR 8609, the Gyro #3 motor current (GRG2_3MC) flagged
out-of-limits high at 106/181052Z with a value of 204.4. The parameter
returned to normal bounds at 106/101058Z.

Following the Gyro #3 event and the subsequent
acquisition/re-acquisition failures, the following ROPs were executed:

ROP DF-14A for RGA bias uplinks at 106/2108Z. 107/0046Z,
107/233Z, and
107/0719Z

ROP IC-2 to turn on SSA-1 for the interval 107/0107Z to
107/0153Z; to turn on
SSA-2 for the intervals 107/050831Z to
107/052955Z, 107/075709Z to
107/081611Z, and 107/085941Z to 107/092257Z.

ROP IC-1 to turn on MATX-1 at 107/041316Z (no acquisition
of signal) and for
the interval 107/041437Z to 107/041936Z; to turn
on MATX-2 for the
interval 107/082018Z to 107/092257Z.

For the Gyro #3 event, the following were performed according to
operations
requests:

Gyro Bias updates at 106/2108Z, 107/0046Z, 107/0233Z and
107/0719Z.

Attitude reference updates at 106/2148Z, 107/0416Z and
107/0905Z.

During the execution of the final attitude reference update at
107/0905Z, per HSTAR 8612, a 486 status buffer message was received
indicating that the system momentum limit had been exceeded.

3.0 SIGNIFICANT FORTHCOMING EVENTS:

Gyro #1 will be powered on this morning, and the gyro configuration
will be modified to reflect active gyros 3, 4, 2, 1, with gyro #3 in the
shadow mode. This is expected to lead to the resumption of
acquisitions/re-acquisitions and consequently science operations.

A Battery #3 capacity test is scheduled to begin at approximately
107/1124Z.

Continuation of Servicing Mission Orbital Verification and the
gradual resumption of normal science observations and calibrations.