Status Report

NASA Hubble Space Telescope Daily Report # 4471

By SpaceRef Editor
October 19, 2007
Filed under , ,
NASA Hubble Space Telescope Daily Report # 4471
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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 # 4471

– Continuing to collect World Class Science

PERIOD COVERED: UT October 18, 2007 (DOY 291)

OBSERVATIONS SCHEDULED

FGS 11211

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a useful result, judged by the over ten refereed citations each year since. It is, however, unsatisfactory to have the direct, parallax-based, distance scale of Population II variables based on a single star. We propose, therefore, to obtain the parallaxes of four additional RR Lyrae stars and two Population II Cepheids, or W Vir stars. The Population II Cepheids lie with the RR Lyrae stars on a common K-band Period-Luminosity relation. Using these parallaxes to inform that relationship, we anticipate a zero-point error of 0.04 magnitude. This result should greatly strengthen confidence in the Population II distance scale and increase our understanding of RR Lyrae star and Pop II Cepheid astrophysics.

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 DARKs. 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.

NIC3 11082

NICMOS Imaging of GOODS: Probing the Evolution of the Earliest Massive Galaxies, Galaxies Beyond Reionization, and the High Redshift Obscured Universe

(uses ACS/SBC and WFPC2)

Deep near-infrared imaging provides the only avenue towards understanding a host of astrophysical problems, including: finding galaxies and AGN at z > 7, the evolution of the most massive galaxies, the triggering of star formation in dusty galaxies, and revealing properties of obscured AGN. As such, we propose to observe 60 selected areas of the GOODS North and South fields with NICMOS Camera 3 in the F160W band pointed at known massive M > 10^11 M_0 galaxies at z > 2 discovered through deep Spitzer imaging. The depth we will reach {26.5 AB at 5 sigma} in H_160 allows us to study the internal properties of these galaxies, including their sizes and morphologies, and to understand how scaling relations such as the Kormendy relationship evolved. Although NIC3 is out of focus and undersampled, it is currently our best opportunity to study these galaxies, while also sampling enough area to perform a general NIR survey 1/3 the size of an ACS GOODS field. These data will be a significant resource, invaluable for many other science goals, including discovering high redshift galaxies at z > 7, the evolution of galaxies onto the Hubble sequence, as well as examining obscured AGN and dusty star formation at z > 1.5. The GOODS fields are the natural location for HST to perform a deep NICMOS imaging program, as extensive data from space and ground based observatories such as Chandra, GALEX, Spitzer, NOAO, Keck, Subaru, VLT, JCMT, and the VLA are currently available for these regions. Deep high-resolution near-infrared observations are the one missing ingredient to this survey, filling in an important gap to create the deepest, largest, and most uniform data set for studying the faint and distant universe. The importance of these images will increase with time as new facilities come on line, most notably WFC3 and ALMA, and for the planning of future JWST observations.

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 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still largely an open problem in cosmology: how does the Universe evolve from large linear scales dominated by dark matter to the highly non-linear scales of galaxies, where baryons and dark matter both play important, interacting, roles? To understand the complex physical processes involved in their formation scenario, and why they have the tight scaling relations that we observe today {e.g. the Fundamental Plane}, it is critically important not only to understand their stellar structure, but also their dark-matter distribution from the smallest to the largest scales. Over the last three years the SLACS collaboration has developed a toolbox to tackle these issues in a unique and encompassing way by combining new non-parametric strong lensing techniques, stellar dynamics, and most recently weak gravitational lensing, with high-quality Hubble Space Telescope imaging and VLT/Keck spectroscopic data of early-type lens systems. This allows us to break degeneracies that are inherent to each of these techniques separately and probe the mass structure of early-type galaxies from 0.1 to 100 effective radii. The large dynamic range to which lensing is sensitive allows us both to probe the clumpy substructure of these galaxies, as well as their low-density outer haloes. These methods have convincingly been demonstrated, by our team, using smaller pilot-samples of SLACS lens systems with HST data. In this proposal, we request observing time with WFPC2 and NICMOS to observe 53 strong lens systems from SLACS, to obtain complete multi-color imaging for each system. This would bring the total number of SLACS lens systems to 87 with completed HST imaging and effectively doubles the known number of galaxy-scale strong lenses. The deep HST images enable us to fully exploit our new techniques, beat down low-number statistics, and probe the structure and evolution of early-type galaxies, not only with a uniform data-set an order of magnitude larger than what is available now, but also with a fully coherent and self-consistent methodological approach!

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11029 – ReAcq(2,1,1) failed to RGA Hold (Note, this HSTAR OCCURRED ON DAY 283)

OTA SE review of PTAS processing showed that ReAcq(2,1,1) at 283/05:07:15 failed due to scan step limit exceeded on FGS2.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL 
FGS GSacq               06                 06 
FGS REacq               08                 08 
OBAD with Maneuver      24                 24 

SIGNIFICANT EVENTS: (None)

SpaceRef staff editor.