NASA Hubble Space Telescope Daily Report # 4532

HUBBLE SPACE TELESCOPE DAILY REPORT # 4532

Continuing to collect World Class Science

PERIOD COVERED: UT January 23, 2007 (DOY 023)

OBSERVATIONS SCHEDULED

NIC1/NIC2 10889

The Nature of the Halos and Thick Disks of Spiral Galaxies

We propose to resolve the extra-planar stellar populations of the thick disks and halos of seven nearby, massive, edge-on galaxies using ACS, NICMOS, and WFPC2 in parallel. These observations will provide accurate star counts and color-magnitude diagrams 1.5 magnitudes below the tip of the Red Giant Branch sampled along the two principal axes and one intermediate axis of each galaxy. We will measure the metallicity distribution functions and stellar density profiles from star counts down to very low average surface brightnesses, equivalent to ~32 V-mag per square arcsec. These observations will provide the definitive HST study of extra-planar stellar populations of spiral galaxies. Our targets cover a range in galaxy mass, luminosity, and morphology and as function of these galaxy properties we will provide: – The first systematic study of the radial and isophotal shapes of the diffuse stellar halos of spiral galaxies – The most detailed comparative study to date of thick disk morphologies and stellar populations – A comprehensive analysis of halo and thick disk metallicity distributions as a function of galaxy type and position within the galaxy. – A sensitive search for tidal streams – The first opportunity to directly relate globular cluster systems to their field stellar population We will use these fossil records of the galaxy assembly process preserved in the old stellar populations to test halo and thick disk formation models within the hierarchical galaxy formation scheme. We will test LambdaCDM predictions on sub-galactic scales, where it is difficult to test using CMB and galaxy redshift surveys, and where it faces its most serious difficulties.

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.

WFPC2 11002

A Census of LIRGs in Clusters of Galaxies in the First Half of the Universe from the IRAC Shallow Survey

The incidence of LIRGs and ULIRGs is roughly two orders of magnitude higher in the field at redshift z > 1, and at these redshifts such objects dominate the global star formation activity. Mergers which fuel such activity might be expected to enhance the frequency of LIRGs in dense environments. We propose to use MIPS to obtain a census of LIRGs in z > 1 galaxy clusters from a well defined sample found in the IRAC Shallow Survey. Supporting IRAC and HST ACS data are also requested.

WFPC2 11038

Narrow Band and Ramp Filter Closeout

These observations are to improve calibration of narrow band and ramp filters. We also test for changes in the filter properties during WFPC2’s 14 years on-board HST.

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               06                   06
OBAD with Maneuver      24                   24

SIGNIFICANT EVENTS: (None)