Date: January 26th 2007

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4285

PERIOD COVERED: UT January 24, 2007 (DOY 024)

OBSERVATIONS SCHEDULED

ACS/HRC 11041

ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors The files, biases and dark will be used to create reference files for science calibration This programme will be for the entire lifetime of ACS For cycle 15 the program will cover 18 months 12 1 06->05 31 08 and it has been divied into three different proposal each covering six months The three proposals are 11041-11042-11043

ACS/HRC/WFPC2/NIC3 10842

A Cepheid Distance to the Coma Cluster

We propose to use the Advanced Camera for Surveys to search for Cepheid variables in two spiral galaxies in the core of the Coma cluster A direct application of the canonical primary distance indicator at 100 Mpc will measure the far-field Hubble constant free of many of the systematic uncertainties which beset current determinations relying on secondary indicators Establishing the far-field H_o with Cepheids will provide one of the strongest links in the extragalactic distance scale and will directly calibrate the fiducial fundamental plane of elliptical galaxies in Coma With ACS/HRC, S/N=5 to 10 or better can be reached for Cepheids with periods of 40d to 70d at mean light in 5 orbits with the F606W filter if H_o=72 km/s/Mpc Efficient detection and phasing can be done with twelve epochs optimally spaced for periods of 40-70d

ACS/SBC 10810

The Gas Dissipation Timescale: Constraining Models of Planet Formation

We propose to constrain planet-formation models by searching for molecular hydrogen emission around young {10-50 Myr} solar-type stars that have evidence for evolved dust disks Planet formation models show that the presence of gas in disks is crucial to the formation of BOTH giant and terrestrial planets, influences dust dynamics, and through tidal interactions with giant planets leads to orbital migration However, there is a lack of systematic information on the presence and lifetime of gas residing at planet-forming radii We will use a newly identified broad continuum emission feature of molecular hydrogen at 1600 Angstrom to search for residual gas within an orbital radius of 5-10 AU around young stars that have evolved beyond the optically thick T Tauri phase These observations will enable the most sensitive probe to date of remant gas in circumstellar disks, detecting surfaces densites of ~0 0001 g/cm^2, or less than 10^-5 of the theoretical "mininum mass" solar nebula from which our solar system is thought to have formed Our observations are designed to be synergistic with ongoing searches for gas emission that is being performed using the Spitzer Space Telescope in that the proposed HST observations are ~100 times more sensitive and will have 50 times higher angular resolution These combined studies will provide the most comprehensive view of residual gas in proto- planetary disks and can set important constraints on models of planet formation

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 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 images Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors

NIC3 10861

An ACS Treasury Survey of the Coma cluster of galaxies

We propose to use the unique spatial resolution of HST and ACS to construct a Treasury imaging survey of the core and infall region of the richest local cluster, Coma We will observe samples of thousands of galaxies down to magnitude B=27 3 with the aim of studying in detail the dwarf galaxy population which, according to hierarchical models of galaxy formation, are the earliest galaxies to form in the universe Our initial scientific objectives are: 1} A study of the structure of the dwarf galaxies, including scaling laws, nuclear structure and morphology, to compare with hierarchical and evolutionary models of their formation 2} A study of the stellar populations from colors and color gradients, and how the internal chemical evolution of galaxies is affected by interaction with the cluster gaseous and galaxy environment 3} To determine the effect of the cluster environment upon morphological features, disks, bulges and bars, by comparing these structure in the Coma sample with field galaxy samples 4} Identification of dwarf galaxy samples for further study with the new generation of multi-object and integral-field spectrographs on 8-10 metre class telescopes such as Keck, Subaru, Gemini, and GTC This is the first such survey of a nearby rich cluster It will provide a key database for studies of galaxy formation and evolution, and a very needed reference for comparison with similar galaxy surveys both in lower density environments in the nearby universe, and in high density environments at high redshifts

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 08 08 FGS REacq 07 07 OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)

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