NASA Hubble Space Telescope Daily Report #4978

HUBBLE SPACE TELESCOPE DAILY REPORT #4978

Continuing to Collect World Class Science

PERIOD COVERED: 5am November 23 – 5am November 24, 2009 (DOY 327/10:00z-328/10:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 11879

CCD Daily Monitor (Part 1)

This program comprises basic tests for measuring the read noise and dark current of the ACS WFC and for tracking the growth of hot pixels. The recorded frames are used to create bias and dark reference images for science data reduction and calibration. This program will be executed four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To facilitate scheduling, this program is split into three proposals. This proposal covers 352 orbits (22 weeks) from 31 August 2009 to 31 January 2010.

COS/FUV 11895

FUV Detector Dark Monitor

The purpose of this proposal is to monitor the FUV detector dark rate by taking long science exposures without illuminating the detector. The detector dark rate and spatial distribution of counts will be compared to pre-launch and SMOV data in order to verify the nominal operation of the detector. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA. Dependence of dark rate as function of time will also be tracked.

COS/NUV 11894

NUV Detector Dark Monitor

The purpose of this proposal is to measure the NUV detector dark rate by taking long science exposures with no light on the detector. The detector dark rate and spatial distribution of counts will be compared to pre-launch and SMOV data in order to verify the nominal operation of the detector. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA. Dependence of dark rate as function of time will also be tracked.

COS/NUV/FUV/WFC3/UVIS/IR 11530

COS-GTO: Alien Dwarfs

Originally identified by Eggen on the basis of their much slower motion about the Galactic center than the local standard of rest, the Arcturus Moving Group likely consists of stars captured from a disrupted satellite of our Galaxy. These stars have low metal abundances and peculiar alpha element abundances. COS spectra will be used to determine whether metal poverty changes the heating, structure, and the dynamics of the outer layers of these stars.

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current draw information is collected, monitored, and saved to DCE memory. Every 10 msec the detector samples the currents from the HV power supplies (HVIA, HVIB) and the AUX power supply (AUXI). The last 1000 samples are saved in memory, along with a histogram of the number of occurrences of each current value.

In the case of a HV transient (known as a “crackle” on FUSE), where one of these currents exceeds a preset threshold for a persistence time, the HV will shut down, and the DCE memory will be dumped and examined as part of the recovery procedure. However, if the current exceeds the threshold for less than the persistence time (a “mini-crackle” in FUSE parlance), there is no way to know without dumping DCE memory. By dumping and examining the histograms regularly, we will be able to monitor any changes in the rate of “mini-crackles” and thus learn something about the state of the detector.

STIS/CCD 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is 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, to build up high-S/N superbiases and track the evolution of hot columns.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each detector. However, starting Oct 5, pairs are only included for weeks that the LRP has external MAMA observations planned. The weekly pairs of exposures for each detector are linked so that they are taken at opposite ends of the same SAA free interval. This pairing of exposures will make it easier to separate long and short term temporal variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once every six months. These are groups of five 1314s FUV-MAMA Time-Tag darks or five 3x315s NUV ACCUM darks distributed over a single SAA-free interval. This will give more information on the brightness of the FUV MAMA dark current as a function of the amount of time that the HV has been on, and for the NUV MAMA will give a better measure of the short term temperature dependence.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more reliably removed from science data using darks taken with the same exposure sequences as the science data, than with a single dark current image scaled by desired exposure time. Therefore, dark current images must be collected using all sample sequences that will be used in science observations. These observations will be used to monitor changes in the dark current of the WFC3-IR channel on a day-to-day basis, and to build calibration dark current ramps for each of the sample sequences to be used by Gos in Cycle 17. For each sample sequence/array size combination, a median ramp will be created and delivered to the calibration database system (CDBS).

WFC3/UVIS 11583

The Star Formation Rate In Nearby Elliptical Galaxies

Small amounts of star formation in normal elliptical galaxies are suggested by several results: some surprisingly young ages from optical line-index dating; cooling X-ray gas; and mid-IR dust emission. Previously, it was difficult to detect low levels of star formation, but UV imaging with WFPC3 will permit us to conclusively identify individual O/B stars in nearby normal ellipticals by their UV colors and magnitudes. This technique is orders of magnitude more sensitive than previous methods, allowing detections of star formation to levels of 1E-4 Msolar/yr. Proof of concept is provided by a very long UV ACS observation of M87 that revealed many O/B stars. We propose observations of four normal ellipticals where recent star formation is likely. This will yield their star formation rates and the locations of such activity.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (Proposal 11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)

HSTARS:

#12101 GSAcq(2,1,1) @328/06:11:12z and REAcq(2,1,1) @328/07:45:50z both failed to Fine Lock Backup on FGS2 during LOS

Observations possibly affected: ACS #9-10 Proposal #11724

COMPLETED OPS REQUEST:

#18765-0 Update BM SOC, SOC-1 and SOC-2 Safing Tests and PSI Test Limits – Nov 2009 @327/17:30z

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL

FGS GSAcq                 6               6

FGS REAcq                 9               9

OBAD with Maneuver        2               2

SIGNIFICANT EVENTS:

At 2009/327/17:30z, via Ops Request #18765-0, the FSW benchmark, SOC 1, and SOC 2 were increased by 100Ah to 485Ah, 382Ah, and 317Ah respectively and the battery pressure test limit was adjusted to an equivalent of 300Ah.