THE NEXT REPORT WILL BE PUBLISHED ON DECEMBER 26th 2006


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT        # 4265

PERIOD COVERED: UT December 21, 2006 (DOY 355)

OBSERVATIONS SCHEDULED

ACS/HRC 10556

Neutral Gas at Redshift z=0.5

Damped Lyman-alpha systems {DLAs} are used to track the bulk of the
neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy, they
could only be studied from the ground at redshifts z>1.65. However, HST
has now permitted us to discover 41 DLAs at z<1.65 in our previous
surveys. Followup studies of these systems are providing a wealth of
information about the evolution of the neutral gas phase component of
the Universe. But one problem is that these 41 low-redshift systems are
spread over a wide range of redshifts spanning nearly 70% of the age of
the Universe. Consequently, past surveys for low-redshift DLAs have not
been able to offer very good precision in any small redshift regime.
Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift
interval z=[0.37, 0.7] which we estimate will permit us to discover
another 41 DLAs. This will not only allow us to double the number of
low-redshift DLAs, but it will also provide a relatively high-precision
regime in the low-redshift Universe that can be used to anchor
evolutionary studies. Fortunately DLAs have high absorption equivalent
width, so ACS-HRC-PR200L has high-enough resoultion to perform this
proposed MgII-selected DLA survey.

ACS/HRC 10800

Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have
relatively fragile test particles which can be used as tracers of the
early dynamical evolution of the outer Solar System. We propose to
continue a Snapshot program using the ACS/HRC that has a demonstrated
discovery potential an order of magnitude higher than the HST
observations that have already discovered the majority of known
transneptunian binaries. With this continuation we seek to reach the
original goals of this project: to accumulate a sufficiently large
sample in each of the distinct populations collected in the Kuiper Belt
to be able to measure, with statistical significance, how the fraction
of binaries varies as a function of their particular dynamical paths
into the Kuiper Belt. Today's Kuiper Belt bears the imprints of the
final stages of giant-planet building and migration; binaries may offer
some of the best preserved evidence of that long-ago era.

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/WFC 10809

The nature of "dry" mergers in the nearby Universe

Recent studies have shown that "dry" mergers of red, bulge-dominated
galaxies at low redshift play an important role in shaping today's most
massive ellipticals. These mergers have been identified in extremely
deep ground-based images of red sequence galaxies at z ~ 0.1. The
ground-based images reach surface brightness limits of AB ~ 29, but lack
the resolution to study the morphologies of the galaxies inside the
effective radius. Here we propose to obtain ACS images of a
representative sample of 40 of these red sequence galaxies: 15 ongoing
dry mergers, 15 remnants, and 10 undisturbed objects. We will measure
the isophote shapes and ellipticities of the galaxies, their dust
content, morphological fine structure {shells and ripples}, AGN content,
and their location on the Fundamental Plane. By comparing galaxies in
different stages of the merging process we can constrain the amount of
gas associated with these red mergers, the effect of active nuclei, and
track structural changes. As two galaxies can be observed in a single
orbit 20 orbits are requested to observe the 40 galaxies.

ACS/WFC 10831

A new wide-separation Einstein Cross at z=2.7

We propose ACS F555W and F814W imaging observations of a new
wide-separation Einstein Cross selected from SDSS spectroscopy through a
bright anomalous emission line and confirmed recently with Keck imaging
and spectroscopy. The source galaxy is a moderately luminous {L~0.2L*}
Lyman-alpha emitter at z=2.699, which is magnified and extended by more
than a factor of twenty, making it one of the most accessible
high-redshift bright Ly-a emitters on the sky. Its apparent flux is only
1.2 magnitudes fainter than MS1612-cB58, making this an ideal system for
detailed study of the metallicity and initial mass function of a
high-redshift star forming galaxy. The Einstein Radius is ~1.8arcsec,
one of the widest known, making future spectroscopic ground-based
followup optimal. This angle subtends ~5 kpc at the lens galaxy at
z=0.331. The high resolution, high signal to noise imaging we propose to
obtain will allow us to build accurate lensing models, including source
reconstructions; combined with existing and planned Keck spectroscopy,
will make possible a map of the host dark matter halo density profile to
greater than one effective light radius; and will reveal lower surface
brightness features associated with the bright star-forming knot lensed
into the Cross. Finally, it will be an exquisite Hubble Heritage galaxy,
which will be indispensable for many other applications. We are
requesting a very modest proprietary period, in order to provide
high-level reductions and ancillary data publically available
simultaneously.

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.

NIC2, ACS/WFC 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.

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and
highly non-uniform archive, making comprehensive comparative studies
among galaxies essentially impossible. We propose to secure HST's
lasting impact on the study of nearby galaxies by undertaking a
systematic, complete, and carefully crafted imaging survey of ALL
galaxies in the Local Universe outside the Local Group. The resulting
images will allow unprecedented measurements of: {1} the star formation
history {SFH} of a >100 Mpc^3 volume of the Universe with a time
resolution of Delta[log{t}]=0.25; {2} correlations between spatially
resolved SFHs and environment; {3} the structure and properties of thick
disks and stellar halos; and {4} the color distributions, sizes, and
specific frequencies of globular and disk clusters as a function of
galaxy mass and environment. To reach these goals, we will use a
combination of wide-field tiling and pointed deep imaging to obtain
uniform data on all 72 galaxies within a volume-limited sample extending
to ~3.5 Mpc, with an extension to the M81 group. For each galaxy, the
wide-field imaging will cover out to ~1.5 times the optical radius and
will reach photometric depths of at least 2 magnitudes below the tip of
the red giant branch throughout the limits of the survey volume. One
additional deep pointing per galaxy will reach SNR~10 for red clump
stars, sufficient to recover the ancient SFH from the color-magnitude
diagram. This proposal will produce photometric information for ~100
million stars {comparable to the number in the SDSS survey} and uniform
multi-color images of half a square degree of sky. The resulting archive
will establish the fundamental optical database for nearby galaxies, in
preparation for the shift of high-resolution imaging to the
near-infrared.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:
10567 - REacq(2,1,1) failed to RGA control
          The REacq(2,1,1) scheduled at 355/17:55:05 failed to RGA control. At AOS
          17:59:00 flags were set indicating the REacq failed due to receiving
          stop flags QF2STOPF and QSTOP. OBAD1 had errors of V1= -25.12,
          V2=-1180.99, V3=-10.73 and RSS=1181.31. OBAD2 showed errors of V1=-1.06,
          V2=3.48, V3=-2.47 and RSS= 4.40. The Map at 18:02 showed erros of
          V1=-1.88, V2=1.23, V3=-2.42 and RSS=3.30.

10568 - REAcq (2,1,1) failed to RGA Hold (Gyro Control)
          At 355/19:42:15 REAcq (2,1,1) scheduled from 355/19:31:05-19:38:16 had
          failed to RGA Hold (Gyro Control). Flag for QF2STOPF was set.
          OBAD #1 RSS: 482.12
          OBAD #2 RSS: 5.49
          OBAD MAP: Not scheduled

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                        SCHEDULED      SUCCESSFUL  
FGS GSacq               08                    08                 
FGS REacq                07                   05           
OBAD with Maneuver  30                    30 

SIGNIFICANT EVENTS: (None)