Status Report

NASA Hubble Space Telescope Daily Report # 4566

By SpaceRef Editor
March 13, 2008
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NASA Hubble Space Telescope Daily Report # 4566
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HUBBLE SPACE TELESCOPE DAILY REPORT # 4566

Continuing to collect World Class Science

PERIOD COVERED: UT March 12, 2008 (DOY 072)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration – CR Persistence Part 6

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=3Ddate/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 i mages. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.

NIC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

We aim to determine physical properties of IR luminous galaxies at 0.3 0.8mJy and their mid-IR spectra have already provided the majority targets with spectroscopic redshifts {0.31 ULIRGs, as in the local Universe. {2} study the co-evolution of star formation and blackhole accretion by investigating the relations between the fraction of starburst/AGN measured from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the current best estimates of the far-IR emission, thus L{bol} for this sample, and establish if the relative contribution of mid-to-far IR dust emission is correlated with morphology {resolved vs. unresolved}.

NIC3 11149

Characterizing the Stellar Populations in Lyman-Alpha Emitters and Lyman Break Galaxies at 5.7 The epoch of reionization marks a major phase transition of the Universe, during which the intergalactic space became transparent to UV photons. Determining when this occurred and the physical processes involved represents the latest frontier in observational cosmology. Over the last few years, searches have intensified to identify the population of high-redshift (z>6) galaxies that might be responsible for this process, but the progress is hampered partly by the difficulty of obtaining physical information (stellar mass, age, star formation rate/history) for individual sources. This is because the number of z>6 galaxies that have both secure spectroscopic redshifts and high-quality infrared photometry (especially with Spitzer/IRAC) is still fairly small. Considering that only several photometric points are available per source, and that many model SEDs are highly degenerate, it is crucial to obtain as many observational constraints as possible for each source to ensure the validity of SED modeling. To better understand the physical properties of high-redshift galaxies, we propose here to conduct HST/NICMOS (72 orbits) and Spitzer/IRAC (102 hours) imaging of spectroscopically confirmed, bright (z<26 mag (AB)) Ly-alpha emitters (LAEs) and Lyman-break galaxies (LBGs) at 5.76 as suggested recently? (2) Is Ly-alpha emission systematically suppressed at z>6 with respect to continuum emission? (i.e., are we reaching the epoch of incomplete reionization?), and (3) Do we see any sign of abnormally young stellar population in any of the z>6 galaxies?

WFPC2 11113

Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution

The discovery of binaries in the Kuiper Belt and related small body populations is powering a revolutionary step forward in the study of this remote region. Three quarters of the known binaries in the Kuiper Belt have been discovered with HST, most by our snapshot surveys. The statistics derived from this work are beginning to yield surprising and unexpected results. We have found a strong concentration of binaries among low-inclination Classicals, a possible size cutoff to binaries among the Centaurs, an apparent preference for nearly equal mass binaries, and a strong increase in the number of binaries at small separations. We propose to continue this successful program in Cycle 16; we expect to discover at least 13 new binary systems, targeted to subgroups where these discoveries can have the greatest impact.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens a window into dynamical conditions in the protoplanetary disk where they formed as well as the history of subsequent events which sculpted the outer Solar System and emplaced them onto their present day heliocentric orbits. To date, at least 47 TNBs have been discovered, but only about a dozen have had their mutual orbits and separate colors determined, frustrating their use to investigate numerous important scientific questions. The current shortage of data especially cripples scientific investigations requiring statistical comparisons among the ensemble characteristics. We propose to obtain sufficient astrometry and photometry of 23 TNBs to compute their mutual orbits and system masses and to determine separate primary and secondary colors, roughly tripling the sample for which this information is known, as well as extending it to include systems of two near-equal size bodies. To make the most efficient possible use of HST, we will use a Monte Carlo technique to optimally schedule our observations.

WFPC2/NIC3 11144

Building on the Significant NICMOS Investment in GOODS: A Bright, Wide-Area Search for z>=3D7 Galaxies

One of the most exciting frontiers in observational cosmology has been to trace the buildup and evolution of galaxies from very early times. While hierarchical theory teaches us that the star formation rate in galaxies likely starts out small and builds up gradually, only recently has it been possible to see evidence for this observationally through the evolution of the LF from z~6 to z~3. Establishing that this build up occurs from even earlier times {z~7-8} has been difficult, however, due to the small size of current high-redshift z~7-8 samples — now numbering in the range of ~4-10 sources. Expanding the size of these samples is absolutely essential, if we are to push current studies of galaxy buildup back to even earlier times. Fortunately, we should soon be able to do so, thanks to ~50 arcmin**2 of deep {26.9 AB mag at 5 sigma} NICMOS 1.6 micron data that will be available over the two ACS GOODS fields as a result of one recent 180- orbit ACS backup program and a smaller program. These data will nearly triple the deep near-IR imaging currently available and represent a significant resource for finding and characterizing the brightest high-redshift sources — since high-redshift candidates can be easily identified in these data from their red z-H colours. Unfortunately, the red z-H colours of these candidates are not sufficient to determine that these sources are at z>=3D7, and it is important also to have deep photometry at 1.1 microns. To obtain this crucial information, we propose to follow up each of these z-H dropouts with NICMOS at 1.1 microns to determine which are at high redshift and thus significantly expand our sample of luminous, = z>=3D7 galaxies. Since preliminary studies indicate that these candidates occur in only 30% of the NIC3 fields, our follow-up strategy is ~3 times as efficient as without this preselection and 9 times as efficient as a search in a field with no pre-existing data. In total, we expect to identify ~8 luminous z-dropouts and possibly ~2 z~10 J-dropouts as a result of this program, more than tripling the number currently known. The increased sample sizes are important if we are to solidify current conclusions about galaxy buildup and the evolution of the LF from z~8. In addition to the high redshift science, these deep 1.1 micron data would have significant value for many diverse endeavors, including {1} improving our constraints on the stellar mass density at z~7-10 and {2} doubling the number of galaxies at z~6 for which we can estimate dust obscuration.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                      SCHEDULED      SUCCESSFUL
FGS GSacq               05                 05
FGS REacq               10                 10
OBAD with Maneuver      30                 30

SIGNIFICANT EVENTS: (None)

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