HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      #4875

PERIOD COVERED: 5am June 25 - 5am June 26, 2009 (DOY 176/0900z-177/0900z)

OBSERVATIONS SCHEDULED

S/C 11364

Vehicle Disturbance Test

The purpose of the VDT is to measure and characterize uncompensated

environmental disturbances acting upon the HST during normal operation.

The VDT is a passive test (not a forced-response test) used to obtain

signatures for both externally induced (e.g. SCM, SA-3, SSM thermal

gradients) and internally induced (e.g. HGA, RWA, COS and WFC3

mechanisms) disturbances affecting HST LOS pointing. The disturbances

observed will be used as the nominal on-orbit disturbances in pointing

control simulations until the next VDT is run.

The test occurs after release, and most of the VDT can be run during the

BEA period. The -V1 sunpoint portion of the VDT usually occurs after the

BEA period is complete. The VDT shall consist of two separate tests that

need not occur consecutively. The overall duration of the VDT is at

least 13 orbits of spacecraft time including (1) at least 8 orbits at

+V3 sunpoint after achieving thermal equilibrium (at least 36-hours at

+V3 sunpoint) and three out of 8-orbits have RWA Friction Compensation

turned Off, and (2) at least 5 orbits at -V1 sunpoint (all or part of

this segment have RWA Friction Compensation turned Off). At the

beginning of each test, the attitude control law gains are switched to

maneuver gains, and the gyros are commanded to low mode. The nominal

attitude control law configuration will be restored at the end of each

test.

Each test is initiated via SMS execution of stored program macros in the

HST flight computer to switch the attitude control law gains to

low-bandwidth maneuver gains, command the gyros into low mode, terminate

Velocity aberration and parallax (VAP) processing, and manage the status

of on-board RWA Friction Compensation. The nominal attitude control law

configuration will be restored at the end of each test via SMS execution

of stored program macros. The stored program command macros are

developed specifically for the VDT by the Flight Software and Pointing

Control System groups.

STIS07/CCD 11404

CCD Dark and Bias Monitor for SMOV4/Cycle 17 Activity STIS-07

Monitor the darks for the STIS CCD. 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.

WFC3/UV 11424

WFC3 UVIS Initial Alignment

The corrector mechanism will be used to iteratively bring the UVIS

channel of WFC3 into alignment with the OTA using phase retrieval of

focus diverse star images over the field. Three visits are required;

corrector offsets will be uplinked after each visit via realtime

command.

This proposal is activity id WFC3-11

WFC3/IR 11543

IR Tungsten Lamp Cross-Check

This proposal will verify the operation of the spare IR channel

calsystem tungsten lamp. A baseline image set will be established by

obtaining one internal flatfield in each IR filter using the channel's

spare lamp, plus one dark in each of the different sample sequence types

used. An earlier proposal (11423) will have already verified the

operation of the FSM and the primary tungsten bulb. Separate proposals

will obtain additional darks and flatfields in each filter for CDBS

reference file generation (proposals 11447 and 11433)

WFC3/UV 11808

WFC3 UVIS Bowtie Monitor

The UVIS detector was observed during ground testing to occasionally

exhibit flat field and dark variations with a bowtie pattern. These

variations are most significant as ~1% flat field (gain) variations

across the field of view. It is believed that this represents a state or

condition into which the detector can transition for reasons and under

circumstances which are not currently understood. It is also very

unlikely that most science observations will determine the state (bowtie

or no-bowtie) of the detector. Ground test data indicates that this

state is long lived (many hours to ~one day). Hysteresis or memory of

past light exposure is also associated with this state.

Recent evidence suggests that exposing the detector to ~200k to 500k

electrons may quench this state. This proposal obtains an internal flat

field sequence of three exposures: one at 10x full well with two at 0.5x

full well immediately before and after. Each exposure is 3x3 binned to

reduce the data volume required.

These visits should be scheduled 2x per day until further direction is

provided.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS: (None)

COMPLETED OPS REQUEST:

18551-0 - -V1 VDT Gains & Telemetry Configuration @ 177/0130z

18564-1 - Bias update DOY 177 @ 177/0251z

COMPLETED OPS NOTES: (None)

                      SCHEDULED      SUCCESSFUL

FGS GSAcq               5                    5               

FGS REAcq               2                    2                

OBAD with Maneuver 5                    5           

SIGNIFICANT EVENTS:

Flash Report: -V1 VDT Completed:

The -V1 VDT configuration, with reduced bandwidth attitude hold gains,

reaction wheel 0-crossing compensation disabled, and gyro 6 data in

Q4DVP0 telemetry, was established at 2009/175 16:17:39. The VDT data

collection interval passed without incident and the pre-test telemetry

and vehicle control configuration was restored at 2009/177 01:30:50. Ops

Request 18564 was executed after test completion to perform two OBADs

without maneuver. The subsequent guide star acquisition at 177/03:20

succeeded.