NASA Hubble Space Telescope Daily Report #4320
Notice: For the foreseeable future, the daily reports may contain apparent discrepancies between some proposal descriptions and the listed instrument usage. This is due to the conversion of previously approved ACS WFC or HRC observations into WFPC2, or NICMOS observations subsequent to the loss of ACS CCD science capability in late January.
HUBBLE SPACE TELESCOPE DAILY REPORT # 4320
– Continuing to collect World Class Science
PERIOD COVERED: UT March 15, 2007 (DOY 074)
OBSERVATIONS SCHEDULED
ACS/SBC 11050
ACS UV contamination monitor
The observations consist of imaging and spectroscopy with SBC of the cluster NGC 6681 in order to monitor the temporal evolution of the UV sensitivity of the SBC.
FGS 10927
The Weight-Watcher Program for Subdwarfs
We propose to use HST/FGS1r to measure five subdwarf spectroscopic binaries to determine masses for the components. Their metallicities, [Fe/H], range from -0.5 to -2.5, and their projected minimum separations range from 9 to 24 mas. These binaries are resolvable with HST/FGS1r but not any ground-based technique. Currently, there are only two subdwarf systems having any mass measurements. The proposed work will boost the total number of subdwarf systems with masses from two to seven, and allow us to construct the first mass-luminosity relation for low-metallicity stars.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration – CR Persistence Part 6
A new proceedure proposed to alleviate the CR-persistence problem of NICMOS. Dark frames will be obtained immediately upon exiting the SAA contour 23, and everytime 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 i mages. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.
NIC2 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 11080
Exploring the Scaling Laws of Star Formation
As a variety of surveys of the local and distant Universe are approaching a full census of galaxy populations, our attention needs to turn towards understanding and quantifying the physical mechanisms that trigger and regulate the large-scale star formation rates {SFRs} in galaxies.
NIC3 11098
Pinning down the redshift of the J-band dropout JD0910+46
The earliest galaxies in the Universe should have formed at very high redshifts, based both on models of hierarchical structure formation, and on observations of the microwave background polarization by WMAP that require significant ionization of the intergalactic medium before z=10. However, direct observation of sources at z>7 remains highly challenging due to their scarcity and faintness. We recently identified a spatially extended J-band dropout, JD0910+46, that is a promising candidate for a z>10 galaxy. Its spectral energy distribution is more extreme than any previously reported: It is undetected in our 2- orbit J-band observation, with a very red J-H color, yet is bluer in H-K than plausible lower redshift {z~3} model SEDs. These colors are, however, natural for a very high redshift star-burst galaxy in which the Lyman-alpha break has moved mostly or entirely through the F110W band. Here we propose deeper F110W and F187W observations to better map the spectral energy distribution of JD910+46, these have the potential to convincingly reject all low redshift solutions for the origin of the observed colours. We believe the importance of such a discovery adds urgency to the followup, and motivates this DD request. Even in the event that JD0910+46 lies at lower redshift understanding the nature of the object will be of great importance since it may lie in a significant overdensity of galaxies at z~4, and will be an important tool for identifying possible interlopers in samples of ultra high-z galaxies.
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 06 06 FGS REacq 08 08 OBAD with Maneuver 28 28
SIGNIFICANT EVENTS: (None)
