NASA Hubble Space Telescope Daily Report # 4470

Status Report From: Space Telescope Science Institute
Posted: Friday, October 19, 2007


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.


- Continuing to collect World Class Science

PERIOD COVERED: UT October 17, 2007 (DOY 290)


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 11296

HST Observations of Astrophysically Important Visual Binaries

This is a continuation of a project begun in Cycle 7 and continued up through Cycle 14. The program consists of annual FGS or WFPC2 observations of three visual binary stars that will yield fundamental astrophysical results, once their orbits and masses are determined. Our targets are the following: {1} Procyon {P = 40.9 yr}, for which our first WFPC2 images yielded an extremely accurate angular separation of the bright F star and its much fainter white-dwarf companion. Combined with ground-based astrometry of the bright star, our observation significantly revised downward the derived masses, and brought Procyon A into much better agreement with theoretical evolutionary masses for the first time. With the continued monitoring proposed here, we will obtain masses to an accuracy of better than 1%, providing a testbed for theories of both Sun-like stars and white dwarfs. {2} G 107-70, a close double white dwarf {P = 18.5 yr} that promises to add two accurate masses to the tiny handful of white-dwarf masses that are directly known from dynamical measurements. {3} Mu Cas {P = 20.8 yr}, a famous nearby metal-deficient G dwarf for which accurate masses will lead to the stars' helium contents, with cosmological implications. For all three stars, we will also be setting increasingly stringent limits on the presence of planetary- mass bodies in the systems.


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

HSTARS: (None)


                        SCHEDULED      SUCCESSFUL 
FGS GSacq                04                 04 
FGS REacq                09                 09 
OBAD with Maneuver       26                 26 


// end //

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