NASA Hubble Space Telescope Daily Report #4223
HUBBLE SPACE TELESCOPE – DAILY REPORT # 4223
Continuing to collect World Class Science
PERIOD COVERED: UT October 19, 2006 (DOY 292)
OBSERVATIONS SCHEDULED
ACS/WFC 10816
The Formation History of Andromeda’s Extended Metal-Poor Halo
We propose deep ACS imaging in the outer spheroid of the Andromeda galaxy, in order to measure the star formation history of its true halo. For the past 20 years, nearly all studies of the Andromeda “halo” were focused on the spheroid within 30 kpc of the galaxy’s center, a region now known to host significant substructure and populations with high metallicity and intermediate ages. However, two groups have recently discovered an extended metal-poor halo beyond 30 kpc; this population is distinct in its surface-brightness profile, abundance distribution, and kinematics. In earlier cycles, we obtained deep images of the inner spheroid {11 kpc on the minor axis}, outer disk {25 kpc on the major axis}, and giant tidal stream, yielding the complete star formation history in each field. We now propose deep ACS imaging of 4 fields bracketing this 30 kpc transition point in the spheroid, so that the inner spheroid and the extended halo populations can be disentangled, enabling a reconstruction of the star formation history in the halo. A wide age distribution in the halo, as found in the inner spheroid, would imply the halo was assembled through ongoing accretion of satellite galaxies, while a uniformly old population would be a strong indication that the halo was formed during the early rapid collapse of the Andromeda proto-galaxy.
ACS/WFC 10880
The host galaxies of QSO2s: AGN feeding and evolution at high luminosities
Now that the presence of supermassive black holes in the nuclei of galaxies is a well established fact, other questions related to the AGN phenomena still have to be answered. Problems of particular interest are how the AGN gets fed, how the black hole evolves and how the evolution of the black hole is related to the evolution of the galaxy bulge. Here we propose to address some of these issues using ACS/WFC + F775W snapshot images of 73 QSO2s with redshifts in the range 0.3
ACS/WFC 10881
The Ultimate Gravitational Lensing Survey of Cluster Mass and Substructure
We propose a systematic and detailed investigation of the mass, substructure, and thermodynamics of one hundred X-ray luminous galaxy clusters at 0.15
ACS/WFC 10886
The Sloan Lens ACS Survey: Towards 100 New Strong Lenses
As a continuation of the highly successful Sloan Lens ACS {SLACS} Survey for new strong gravitational lenses, we propose one orbit of ACS-WFC F814W imaging for each of 50 high- probability strong galaxy-galaxy lens candidates. These observations will confirm new lens systems and permit immediate and accurate photometry, shape measurement, and mass modeling of the lens galaxies. The lenses delivered by the SLACS Survey all show extended source structure, furnishing more constraints on the projected lens potential than lensed-quasar image positions. In addition, SLACS lenses have lens galaxies that are much brighter than their lensed sources, facilitating detailed photometric and dynamical observation of the former. When confirmed lenses from this proposal are combined with lenses discovered by SLACS in Cycles 13 and 14, we expect the final SLACS lens sample to number 80–100: an approximate doubling of the number of known galaxy-scale strong gravitational lenses and an order-of-magnitude increase in the number of optical Einstein rings. By virtue of its homogeneous selection and sheer size, the SLACS sample will allow an unprecedented exploration of the mass structure of the early-type galaxy population as a function of all other observable quantities. This new sample will be a valuable resource to the astronomical community by enabling qualitatively new strong lensing science, and as such we will waive all but a short {3-month} proprietary period on the observations.
ACS/WFC 10917
Afterglows and Environments of Short-Hard Gamma-Ray Bursts
Discovery of the first afterglows of short-hard bursts {SHBs} has led to a revolution in our understanding of these events, strongly suggesting that they originate in the mergers of compact-object binaries. Capitalizing on this progress, we propose to pursue the next generation of SHB observations with HST, tracking the decay of all accessible SHB afterglows to late times and pinpointing the location of several more within the context of their host galaxies. These observations will allow quantitative analysis of progenitor lifetimes and short burst environments, enable direct confrontation with population synthesis models, and provide updated event rate estimates for the LIGO and VIRGO gravitational-wave detectors that are now coming on-line.
NIC2 10825
The Formation Epoch of Early-type Galaxies: Constraints from the Fundamental Plane at z=1.3
Field and cluster surveys both show a ~50% decrease in the number of early-type galaxies at redshifts near 1. Galaxies that have either recently transformed into early-types or undergone star formation should have younger appearing stellar populations. The resulting change in the mass-to-light ratio can be detected by the offset in the fundamental plane with redshift. We will use the fundamental plane to test whether a significant fraction of early-type galaxies have evidence of recent star formation, using a sample of ~20 z=1.3 cluster and field early-type galaxies. This is 7 times larger than the sample previously used at this redshift. We already have the high signal-to-noise 12-20 hour long Keck spectra for these galaxies we need for velocity dispersions. To use the fundamental plane, we require sizes and surface brightnesses. We propose 12 orbits of NICMOS Camera 2 imaging to measure the sizes and surface brightness distributions of these objects in a rest-frame optical passband. These data will provide high quality surface brightness profiles out two ~2 half-light radii, at wavelengths comparable to previous fundamental plane studies. When combined with our spectra, the HST data will establish the mass-to-light ratio evolution for massive early-type galaxies from the fundamental plane. We will define the epoch of last star formation for these z=1.3 galaxies, directly testing the claims of strong evolution at z=1.
WFPC2 10744
WFPC2 Cycle 14 Decontaminations and Associated Observations
This proposal is for the WFPC2 decontamination. Also included are instrument monitors tied to decontamination: photometric stability check, focus monitor, pre- and post-decontamination internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
10473 – GSACQ(2,1,2) failed, Search Radius Limit Exceeded on FGS 2
GSACQ(2,1,2) at 292/09:21:02 failed due to Search Radius Limit Exceeded on FGS 2 at 09:26:22. OBAD data prior to GSACQ showed RSS attitude correction of 11.71 arcseconds, OBAD map after GSACQ failure showed RSS error of 1.83 arcseconds.
REAcq (2,1,2) at 292.10:54:20 failed due to Search Radius Limit Exceeded on FGS 2 at 10:58:59. OBAD #1: RSS = 812.99 OBAD #2: RSS = 8.84 OBAD MAP: RSS = 8.44
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SIGNIFICANT EVENTS: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 08 07
FGS REacq 08 07
OBAD with Maneuver 32 32
