NASA Hubble Space Telescope Daily Report #4263
HUBBLE SPACE TELESCOPE DAILY REPORT # 4263
– Continuing to collect World Class Science
PERIOD COVERED: UT December 19, 2006 (DOY 3353)
OBSERVATIONS SCHEDULED
ACS/HRC 10800
Kuiper Belt Binaries: Probes of Early Solar System Evolution
Binaries in the Kuiper Belt are a scientific windfall: in them we have relatively fragile test particles which can be used as tracers of the early dynamical evolution of the outer Solar System. We propose to continue a Snapshot program using the ACS/HRC that has a demonstrated discovery potential an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. With this continuation we seek to reach the original goals of this project: to accumulate a sufficiently large sample in each of the distinct populations collected in the Kuiper Belt to be able to measure, with statistical significance, how the fraction of binaries varies as a function of their particular dynamical paths into the Kuiper Belt. Today’s Kuiper Belt bears the imprints of the final stages of giant-planet building and migration; binaries may offer some of the best preserved evidence of that long-ago era.
ACS/WFC 10809
The nature of “dry” mergers in the nearby Universe
Recent studies have shown that “dry” mergers of red, bulge-dominated galaxies at low redshift play an important role in shaping today’s most massive ellipticals. These mergers have been identified in extremely deep ground-based images of red sequence galaxies at z ~ 0.1. The ground-based images reach surface brightness limits of AB ~ 29, but lack the resolution to study the morphologies of the galaxies inside the effective radius. Here we propose to obtain ACS images of a representative sample of 40 of these red sequence galaxies: 15 ongoing dry mergers, 15 remnants, and 10 undisturbed objects. We will measure the isophote shapes and ellipticities of the galaxies, their dust content, morphological fine structure {shells and ripples}, AGN content, and their location on the Fundamental Plane. By comparing galaxies in different stages of the merging process we can constrain the amount of gas associated with these red mergers, the effect of active nuclei, and track structural changes. As two galaxies can be observed in a single orbit 20 orbits are requested to observe the 40 galaxies.
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/WFPC2 10890
Morphologies of the Most Extreme High-Redshift Mid-IR-Luminous Galaxies
The formative phase of the most massive galaxies may be extremely luminous, characterized by intense star- and AGN-formation. Till now, few such galaxies have been unambiguously identified at high redshift, restricting us to the study of low-redshift ultraluminous infrared galaxies as possible analogs. We have recently discovered a sample of objects which may indeed represent this early phase in galaxy formation, and are undertaking an extensive multiwavelength study of this population. These objects are bright at mid-IR wavelengths {F[24um]>0.8mJy}, but deep ground based imaging suggests extremely faint {and in some cases extended} optical counterparts {R~24-27}. Deep K-band images show barely resolved galaxies. Mid-infrared spectroscopy with Spitzer/IRS reveals that they have redshifts z ~ 2-2.5, suggesting bolometric luminosities ~10^{13-14}Lsun! We propose to obtain deep ACS F814W and NIC2 F160W images of these sources and their environs in order to determine kpc-scale morphologies and surface photometry for these galaxies. The proposed observations will help us determine whether these extreme objects are merging systems, massive obscured starbursts {with obscuration on kpc scales!} or very reddened {locally obscured} AGN hosted by intrinsically low-luminosity galaxies.
NIC1/NIC2/NIC3 8794
NICMOS Post-SAA calibration – CR Persistence Part 5
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 USEAFTER 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 DARKSs. 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.
NIC2 10847
Coronagraphic Polarimetry of HST-Resolved Debris Disks
We propose to take full advantage of the recently commissioned coronagraphic polarimetry modes of ACS and NICMOS to obtain imaging polarimetry of circumstellar debris disks that were imaged previously by the HST coronagraphs, but without the polarizers. It is well established that stars form in gas-rich protostellar disks, and that the planets of our solar system formed from a circum-solar disk. However, the connection between the circumstellar disks that we observe around other stars and the processes of planet formation is still very uncertain. Mid-IR spectral studies have suggested that disk grains are growing in the environments of young stellar objects during the putative planet-formation epoch. Furthermore, structures revealed in well resolved images of circumstellar disks suggest gravitational influences on the disks from co-orbital bodies of planetary mass. Unfortunately, existing imaging data provides only rudimentary information abou the disk grains and their environments. Our proposed observations, which can be obtained only with HST, will enable us to quantitatively determine the sizes of the grains and optical depths as functions of their location within the disks {i.e., detailed tomography}. Armed with these well-determine physical and geometrical systemic parameters, we will develop a set of self-consistent models of disk structures to investigate possible interactions between unseen planets and the disks from which they formed. Our results will also calibrate models of the thermal emission from these disks, that will in turn enable us to infer the properties of other debris disks that cannot be spatially resolved with current or planned instruments and telescopes.
NIC2, ACS/WFC 10802
SHOES-Supernovae, HO, for the Equation of State of Dark energy
The present uncertainty in the value of the Hubble constant {resulting in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at redshifts exceeding 1 are now the leading obstacles to determining the nature of dark energy. We propose a single, integrated set of observations for Cycle 15 that will provide a 40% improvement in constraints on dark energy. This program will observe known Cepheids in six reliable hosts of Type Ia supernovae with NICMOS, reducing the uncertainty in H_0 by a factor of two because of the smaller dispersion along the instability strip, the diminished extinction, and the weaker metallicity dependence in the infrared. In parallel with ACS, at the same time the NICMOS observations are underway, we will discover and follow a sample of Type Ia supernovae at z > 1. Together, these measurements, along with prior constraints from WMAP, will provide a great improvement in HST’s ability to distinguish between a static, cosmological constant and dynamical dark energy. The Hubble Space Telescope is the only instrument in the world that can make these IR measurements of Cepheids beyond the Local Group, and it is the only telescope in the world that can be used to find and follow supernovae at z > 1. Our program exploits both of these unique capabilities of HST to learn more about one of the greatest mysteries in science.
NIC3 10792
Quasars at Redshift z=6 and Early Star Formation History
We propose to observe four high-redshift quasars {z=6} in the NIR in order to estimate relative Fe/Mg abundances and the central black hole mass. The results of this study will critically constrain models of joint quasar and galaxy formation, early star formation, and the growth of supermassive black holes. Different time scales and yields for alpha-elements {like O or Mg} and for iron result into an iron enrichment delay of ~0.3 to 0.6 Gyr. Hence, despite the well-known complexity of the FeII emission line spectrum, the ratio iron/alpha – element is a potentially useful cosmological clock. The central black hole mass will be estimated based on a recently revised back hole mass – luminosity relationship. The time delay of the iron enrichment and the time required to form a supermassive black hole {logM>8 Msol, tau ~0.5Gyr} as evidenced by quasar activity will be used to date the beginning of the first intense star formation, marking the formation of the first massive galaxies that host luminous quasars, and to constrain the epoch when supermassive black holes start to grow by accretion.
WFPC2 10745
WFPC2 CYCLE 14 INTERNAL MONITOR
This calibration proposal is the Cycle 14 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.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
10563 – GSAcq(1,3,1) failed to RGA Hold (Gyro Control) The GSAcq(1,3,1) scheduled at 354/00:22:40 – 00:30:45 failed to RGA Hold due to (QF1SRLEX) search radius limit exceeded on FGS-1. Pre-acquisition OBADs showed (RSS) attitude correction values of 3802.35 and 7.23 arcseconds. Post-acquisition OBAD/MAP had 3-axis (RSS) error value of 1.97 arcseconds.
REACQ(1,3,1) at 02:00:06 and 03:13:13 also failed.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 12 11
FGS REacq 03 01
OBAD with Maneuver 28 28
SIGNIFICANT EVENTS:
Flash Report – HST dynamic inertia & aero torque changes – The sequence of configuration changes exercising HST dynamic inertia and aerodynamic torque compensations is complete, and the on-going operational configuration with both compensations enabled has been established. Both compensations are performing as expected.
