Status Report

NASA Hubble Space Telescope Daily Report #4936

By SpaceRef Editor
September 24, 2009
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Continuing to Collect World Class Science

PERIOD COVERED: 5am September 22 – 5am September 23, 2009 (DOY 265/09:00z-266/09:00z)



Photometric Cross-Calibration using Stellar Flux Standards

The purpose of this proposal is to: A) Verify the ACS HRC and WFC photometric calibrations with a repeat visit to one of the three primary WDs. B) Measure the change in sensitivity with time for bright stars (which would include any small CTE contributions). C) Continue to investigate the ~2% discrepancy between ACS flux calibration and that of STIS (ACS ISR 2007-06). The goal is to measure any filter bandpass shifts in ACS or rule out the possibility of shifts as the primary contributors to the ACS/STIS discrepancy for cool stars.

COS/FUV 11482

FUV Detector Dark

The purpose of this proposal is to measure the FUV 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 data in order to verify the nominal operation of the detector, and for use in the CalCOS calibration pipeline. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA.

This is SMOV Activity COS-24.

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 11466

NUV Detector Dark

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 data in order to verify the nominal operation of the detector, and for use in the CalCOS calibration pipeline. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA.

COS/NUV 11481

COS NUV High S/N Verification

The purpose of this proposal is to collect data at several central wavelengths for each NUV grating in Time-Tag mode, using multiple FP-POS positions, in order to verify that high signal-to-noise spectra can be obtained. All spectra will have enough counts to permit standard reduction techniques to be used to obtain spectra with a signal-to-noise ratio of at least 30. Very high signal-to-noise spectra will also be obtained in some medium resolution modes in order to demonstrate that a signal-to-noise ratio of at least 100 is possible.


COS-GTO: QSO Absorbers, Galaxies and Large-Scale Structures in the Local Universe

This is a program to probe the large scale structure of baryons in the universe, including addressing questions of baryon fraction, physical conditions and relationships between absorbers and large-scale structures of galaxies. Besides these specific goals, this proposed GTO program also probes a large enough total path length in Ly alpha and OVI to add significantly to what STIS/FUSE has already observed. Several Galactic High Velocity Cloud Complexes also are probed by these sightlines, particularly the M Complex. The total path length of this proposed program for Ly alpha large-scale structure surveys is delta_z~5.5.

We have selected a variety of targets to address these questions, under the following subcategories:

1. Target 8 bright BL Lac objects to search for low contrast Ly alpha absorbers from the warm-hot interstellar medium (WHIM).

2. Ly alpha cloud sizes: The targets are a bright AGN pair which yield tangential distance separations of 100–500 kpc at z=0.01–0.05, where galaxy surveys are excellent. This pair has two filaments and two voids in this distance range.

3. Probes of starburst outflows: The targets are bright AGN, <= 100 kpc in projection out of the minor axis of nearby starburst galaxies. 4. A large galaxy’s gaseous halo: Three probes of the kinematics and metallicity of a single L* galaxy halo. These observations includes G130M, G160M exposures at SNR~20 and G285M at 2850A and SNR~10 for MgII. The 2L* galaxy, ESO 157-G049 (cz=1678 km/s), being probed by these sightlines has an available H I 21cm map from ATCA, H alpha imaging from CTIO and long-slit spectra from MSSSO. 5. Dwarf galaxy winds: These targets probe the kinematics and metallicities of outflows from active and inactive (in terms of star formation) dwarfs. FGS 11704 The Ages of Globular Clusters and the Population II Distance Scale Globular clusters are the oldest objects in the universe whose age can be accurately determined. The dominant error in globular cluster age determinations is the uncertain Population II distance scale. We propose to use FGS 1R to obtain parallaxes with an accuracy of 0.2 milliarcsecond for 9 main sequence stars with [Fe/H] < -1.5. This will determine the absolute magnitude of these stars with accuracies of 0.04 to 0.06mag. This data will be used to determine the distance to 24 metal-poor globular clusters using main sequence fitting. These distances (with errors of 0.05 mag) will be used to determine the ages of globular clusters using the luminosity of the subgiant branch as an age indicator. This will yield absolute ages with an accuracy of 5%, about a factor of two improvement over current estimates. Coupled with existing parallaxes for more metal-rich stars, we will be able to accurately determine the age for globular clusters over a wide range of metallicities in order to study the early formation history of the Milky Way and provide an independent estimate of the age of the universe. The Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an absolute magnitude error less than 0.18 mag which is suitable for use in main sequence fitting. Previous attempts at main sequence fitting to metal-poor globular clusters have had to rely on theoretical calibrations of the color of the main sequence. Our HST parallax program will remove this source of possible systematic error and yield distances to metal- poor globular clusters which are significantly more accurate than possible with the current parallax data. The HST parallax data will have errors which are 10 times smaller than the current parallax data. Using the HST parallaxes, we will obtain main sequence fitting distances to 11 globular clusters which contain over 500 RR Lyrae stars. This will allow us to calibrate the absolute magnitude of RR Lyrae stars, a commonly used Population II distance indicator. NIC1/NIC2/NIC3 11947 Extended Dark Monitoring This program takes a series of darks to obtain darks (including amplifier glow, dark current, and shading profiles) for all three cameras in the read-out sequences used in Cycle 17. A set of 12 orbits will be observed every two months for a total of 72 orbits for a 12 month Cycle 17. This is a continuation of Cycle 16 program 11330 scaled down by ~80%. The first orbit (Visit A0) should be scheduled in the NICMOS SMOV after the DC Transfer Test (11406) and at least 36h before the Filter Wheel Test (11407). Data download using fast track. The following 28 orbits (visit A1-N2) should be scheduled AFTER the SMOV Proposal 11407 (Filter Wheel Test). This is done in order to monitor the dark current following an adjustment of the NCS set-point. These visits should be executed until the final temperature is reached during SMOV. NIC1/NIC2/NIC3 8795 NICMOS Post-SAA Calibration – CR Persistence Part 6 This is a new procedure proposed to alleviate the CR-persistence problem of NICMOS. Dark frames will be obtained immediately upon exiting the SAA contour 23, and every time a NICMOS exposure is scheduled within 50 minutes of coming out of the SAA. The darks will be obtained in parallel in all three NICMOS cameras. The post-SAA darks will be non-standard reference files available to users with a ‘Use After’ date/time mark. The keyword ‘UseAfter=date/time’ will also be added to the header of each post-SAA dark frame. The keyword must be populated with the time, in addition to the date, because HST crosses the SAA ~8 times per day, so each post-SAA dark will need to have the appropriate time specified, for users to identify the ones they need. Both the raw and processed images will be archived as post-SAA darks. Generally we expect that all NICMOS science/calibration observations started within 50 minutes of leaving an SAA will need such MAPs to remove the CR persistence from the science images. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors. 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/ACS/IR 11359 Panchromatic WFC3 Survey of Galaxies at Intermediate z: Early Release Science Program for Wide Field Camera 3 The unique panchromatic capabilities of WFC3 will be used to survey the structure and evolution of galaxies at the peak of the galaxy assembly epoch. Deep ultraviolet and near-IR imaging and slitless spectroscopy of existing deep multi-color ACS fields will be used to gauge star-formation and the growth of stellar mass as a function of morphology, structure and surrounding density in the critical epoch 1 < z < 4. Images in the F225W, F275W, and F336W filters will identify galaxies at z < 1.5 from their UV continuum breaks, and provide star-formation indicators tied directly to both local and z > 3 populations. Deep near-IR (F125W and F160W) images will probe the stellar mass function well below 10^9 Msun for mass-complete samples. Lastly, the WFC3 slitless UV and near-IR grisms will be used to measure redshifts and star-formation rates from H- alpha and rest-frame UV continuum slope. This WFC3 ERS program will survey one 4 x 2 mosaic for a total area of 50 square arcminutes to 5-sigma depths of m_AB = 27 in most filters from the mid-UV through the near-IR.

This multicolor high spatial resolution data set will allow the user to gauge the growth of galaxies through star-formation and merging. High precision photometric and low- resolution spectroscopic redshifts will allow accurate determinations of the faint-end of the luminosity and mass functions, and will shed light on merging and tidal disruption of stellar and gaseous disks. The WFC3 images will also allow detailed studies of the internal structure of galaxies, and the distribution of young and old stellar populations. This program will demonstrate the unique power of WFC3 by applying its many diverse modes and full panchromatic capability to a forefront problem in astrophysics.

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/IR/S/C 12006

CSM Test

The purpose of this proposal is to test of the repeatability of the CSM mechanism as measured using bright IR blobs. This proposal will also test the amount of motion of the CSM per commanded CSM step. This proposal observe the same field, with a high background level, using increasing number of CSM steps and then progressively moves the CSM back, backtracking the first half of the observations.

WFC3/UVIS 11559

Jovian Upheaval and Its Impact on Vortices

We propose observations of Jupiter with global coverage at high resolution to quantify changes in its atmosphere during and following the global upheaval. Only HST has the capability to obtain images with enough spatial resolution and contrast to extract velocity fields (we will use our newly developed technique to accomplish this), and with WFC3 we can image Jupiter in its entirety in a single exposure. We are in particular interested in the Red Oval BA: Will the Oval be long lived, remain red, or turn white again, disappear? Both the merger of its precursors, and change in color has never before been witnessed. The Great Red Spot: This storm system appears to decrease in size and has become rounder, both as derived from its associated cloud deck, but also from its potential vorticity, a more dynamically-relevant quantity. How will the GRS evolve? Will it swallow the new vortices detected in amateur images at this same latitude band? How will this effect the potential vorticity? In addition, we hope to understand disturbances and stagnation points, both of which were detected during the present global upheaval: are these cyclonic regions, can they spawn anticyclones (as suggested by amateur images)?

WFC3/UVIS 11657

The Population of Compact Planetary Nebulae in the Galactic Disk

We propose to secure narrow- and broad-band images of compact planetary nebulae (PNe) in the Galactic Disk to study the missing link of the early phases of post-AGB evolution. Ejected AGB envelopes become PNe when the gas is ionized. PNe expand, and, when large enough, can be studied in detail from the ground. In the interim, only the HST capabilities can resolve their size, morphology, and central stars. Our proposed observations will be the basis for a systematic study of the onset of morphology. Dust properties of the proposed targets will be available through approved Spitzer/IRS spectra, and so will the abundances of the alpha-elements. We will be able thus to explore the interconnection of morphology, dust grains, stellar evolution, and populations. The target selection is suitable to explore the nebular and stellar properties across the Galactic Disk, and to set constraints on the galactic evolutionary models through the analysis of metallicity and population gradients.

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).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the UVIS detector (both CCDs) at the level of ~1%, lasting hours to days. Initially found via an unexpected bowtie-shaped feature in flatfield ratios, subsequent lab tests on similar e2v devices have since shown that it is also present as simply an overall offset across the entire CCD, i.e., a QE offset without any discernable pattern. These lab tests have further revealed that overexposing the detector to count levels several times full well fills the traps and effectively neutralizes the bowtie. Each visit in this proposal acquires a set of three 3×3 binned internal flatfields: the first unsaturated image will be used to detect any bowtie, the second, highly exposed image will neutralize the bowtie if it is present, and the final image will allow for verification that the bowtie is gone.


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


12018 – GSAcq (1,2,1), scheduled from 265/09:27:51z – 265/09:34:40z, resulted in Fine Lock Back-up (1,0,1).

Observations possibly affected: COS 119 Proposal ID# 11895; STIS 20 & 21, Proposal ID# 11889.

12021 – WFC3 Channel Select Mechanism (CSM) move scheduled at 265/22:53:50z was unsuccessful because the final position achieved was not within tolerance of the desired position.

Observations affected: WFC3 33 – 36 Proposal Id#12006.



1912-0 – Adjust WFC3 FSW Error Count @ 266/0043z

FGS GSAcq 13 13
FGS REAcq 02 02
OBAD with Maneuver 13 13


SpaceRef staff editor.