NASA Hubble Space Telescope Daily Report # 4468
Notice: Due to the conversion of some ACS WFC or HRC observations into WFPC2, or NICMOS observations after the loss of ACS CCD science capability in January, there may be an occasional discrepancy between a proposal’s listed (and correct) instrument usage and the abstract that follows it.
HUBBLE SPACE TELESCOPE DAILY REPORT # 4468
– Continuing to collect World Class Science
PERIOD COVERED: UT October 15, 2007 (DOY 288)
OBSERVATIONS SCHEDULED
WFPC2 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
This calibration proposal is the Cycle 15 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays {both gain 7 and gain 15 — to test stability of gains and bias levels}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. These also provide raw data for generating annual super-bias reference files for the calibration pipeline.
NIC3 11107
Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe
We have used the ultraviolet all-sky imaging survey currently being conducted by the Galaxy Evolution Explorer {GALEX} to identify for the first time a rare population of low- redshift starbursts with properties remarkably similar to high-redshift Lyman Break Galaxies {LBGs}. These “compact UV luminous galaxies” {UVLGs} resemble LBGs in terms of size, SFR, surface brightness, mass, metallicity, kinematics, dust, and color. The UVLG sample offers the unique opportunity of investigating some very important properties of LBGs that have remained virtually inaccessible at high redshift: their morphology and the mechanism that drives their star formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS in order to 1} characterize their morphology and look for signs of interactions and mergers, and 2} probe their star formation histories over a variety of timescales. The images show a striking trend of small-scale mergers turning large amounts of gas into vigorous starbursts {a process referred to as dissipational or “wet” merging}. Here, we propose to complete our sample of 31 LBG analogs using the ACS/SBC F150LP {FUV} and WFPC2 F606W {R} filters in order to create a statistical sample to study the mechanism that triggers star formation in UVLGs and its implications for the nature of LBGs. Specifically, we will 1} study the trend between galaxy merging and SFR in UVLGs, 2} artificially redshift the FUV images to z=1-4 and compare morphologies with those in similarly sized samples of LBGs at the same rest-frame wavelengths in e.g. GOODS, UDF, and COSMOS, 3} determine the presence and morphology of significant stellar mass in “pre-burst” stars, and 4} study their immediate environment. Together with our Spitzer {IRAC+MIPS}, GALEX, SDSS and radio data, the HST observations will form a unique union of data that may for the first time shed light on how the earliest major episodes of star formation in high redshift galaxies came about. This proposal was adapted from an ACS HRC+WFC proposal to meet the new Cycle 16 observing constraints, and can be carried out using the ACS/SBC and WFPC2 without compromising our original science goals.
WFPC2 11023
WFPC2 CYCLE 15 Standard Darks – part 1
This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs.
WFPC2 11141
White dwarfs in the open star cluster NGC 188
White dwarf cooling sequences represent the only ways in which we can determine ages of Galactic components such as the disk and the halo, and they are an independent check on main sequence ages of globular star clusters. These age measurements rely heavily on theoretical cooling models, many of which disagree by as much as a few gigayears for the coolest white dwarfs. Further, observations of the white dwarf sequence in the super metal- rich open cluster NGC 6791 have found a white dwarf age several gigayears younger than the accepted cluster age determined by main-sequence fitting. The white dwarf sequence of the solar-metallicity, 7-Gyr old open cluster NGC 188 can provide some much-needed insight into these uncertainties, but previous HST observations were too shallow to detect the oldest, faintest white dwarfs in the cluster. We propose deep imaging of two fields at the center of the cluster with the following goals: {1} To detect the end of the white dwarf cooling sequence, providing a much-needed empirical data point for cool white dwarf evolutionary models, {2} to compare the white dwarf luminosity function of NGC 188 with that of NGC 6791 to determine if the odd white dwarf sequence in the latter cluster is due to the cluster’s high metallicity or due to a shortcoming in theoretical models, and {3} to determine via photometry the masses of white dwarfs formed by solar-mass stars, a quantity not yet empirically measured.
WFPC2 11170
UV Imaging of the Martian Corona and the Escape of Hydrogen
ACS SBC UV imaging observations of Mars are proposed to study the extended hydrogen corona, with application to the escape of hydrogen and the history of water on Mars. These observations will be scheduled when Mars is distant from the Earth, so that a field of view of +/- 4-5 Mars radii can be obtained to image the full range of the highly extended martian hydrogen corona through its H Ly alpha emission. The observations will also be obtained when the Sun-Earth-Mars angle is close to 90 degrees, so that any asymmetry along the Mars-Sun line can be observed. The observed 2-dimensional brightness distribution will be related to local density using two existing radiative transfer codes, and the upward flux and velocity distributions will be determined by comparison with runs from an exospheric distribution model. These observations, combined with simultaneous Ly alpha observations by the SPICAM instrument on Mars Express from within the atmosphere, will provide the first tight constraints on the total escape flux and importance of nonthermal processes on the rate of escape.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
11024 – GSAcq(2,1,2) failed to RGA Hold (Gyro Control) Upon acquisition of signal at 288/09:56:46, the GSAcq(2,1,2) scheduled at 288/09:26:40 – 09:34:44 had failed to RGA Hold due to (QF2STOPF) stop flag indication on FGS-2. Pre-acquisition OBAD1 (RSS) attitude correction error not available due to LOS. OBAD2 had (RSS) value of 4.86 arcseconds
REACQ(2,1,2) at 11:00:00 was successful.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FGS GSacq 06 05 FGS REacq 09 09 OBAD with Maneuver 30 30
SIGNIFICANT EVENTS: (None)
