Daily # 4197

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4197

PERIOD COVERED: UT September 12, 2006 (DOY 255)

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 z1.65.
However, HST has now permitted us to discover 41 DLAs at z1.65 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/WFC 10258

Tracing the Emergence of the Hubble Sequence Among the Most Luminous
and Massive Galaxies

There is mounting evidence that the redshift range 1 z 2 was an
important era when massive galaxies assembled their stellar content
and assumed their present--day morphologies. Despite extensive HST
imaging surveys, however, there is very little data in the optical
rest frame {i.e., observed near--infrared} on the morphologies of the
most luminous galaxies at these redshifts. We propose to image a
carefully selected set of 20 of the most luminous, K--band selected
GOODS galaxies at 1.3 z 2, using NICMOS camera 2. This offers
diffraction--limited, critically sampled imaging at 1.6 microns to
ensure the best angular resolution for comparison to ACS. The galaxies
are chosen to span a simple 4--fold parameter space of morphological
and spectral type, in order to provide the most information about the
variety of massive galaxy properties in this redshift range. We will
investigate the emergence of large scale--length disks, stable spiral
structure, mature bulges with red stellar populations, central bar
structures, the incidence of disturbed morphology, the existence {or
lack thereof} of blue ellipticals, and other questions that concern
the evolution and maturation of the brightest, largest, and most
massive ordinary galaxies in this critical redshift range.

ACS/WFC 10486

A Cosmic String Lens Candidate

We propose two-band imaging observations with ACS of a cosmic string
lens candidate, CSL-1, to look for a feature predicted by the cosmic
string model: a low-surface brightness discontinuity in between the
two galaxy images.

ACS/WFC 10881

The Ultimate Gravitational Lensing Survey of Cluster Mass and
Substructure

We propose a systematic and detailed investigation of the mass,
substructure, and thermodynamics of one hundred X-ray luminous galaxy
clusters at 0.15z0.3. The primary goal is to test our recent
suggestion that this population is dominated by dynamically immature
disturbed clusters, and that the observed mass-temperature relation
suffers strong structural segregation. If confirmed, this would
represent a paradigm shift in our observational understanding of
clusters, that were hitherto believed to be dominated by mature,
undisturbed systems. The key observation to this endeavor is Hubble
imaging of cluster cores to identify robustly tangential and radial
multiple arcs and measure the shape of faint galaxies. These strong
and weak lensing signals will give an accurate measure of the total
mass and structure of the dark matter distribution that we will
subsequently compare with X-ray and Sunyaev Zeldovich Effect
observables. The broader applications of our project include 1} the
calibration of mass-temperature and mass-SZE scaling relations which
will be critical for the calibration of proposed dark energy
experiments, and 2} the low redshift baseline study of the
demographics of massive clusters to aid interpretation of future high
redshift {z1} cluster samples. For this ultimate cluster survey, we
request ACS SNAPSHOTS through the F606W filter drawn from a target
list of 143 clusters.

ACS/WFC 10886

The Sloan Lens ACS Survey: Towards 100 New Strong Lenses

As a continuation of the highly successful Sloan Lens ACS {SLACS}
Survey for new strong gravitational lenses, we propose one orbit of
ACS-WFC F814W imaging for each of 50 high- probability strong
galaxy-galaxy lens candidates. These observations will confirm new
lens systems and permit immediate and accurate photometry, shape
measurement, and mass modeling of the lens galaxies. The lenses
delivered by the SLACS Survey all show extended source structure,
furnishing more constraints on the projected lens potential than
lensed-quasar image positions. In addition, SLACS lenses have lens
galaxies that are much brighter than their lensed sources,
facilitating detailed photometric and dynamical observation of the
former. When confirmed lenses from this proposal are combined with
lenses discovered by SLACS in Cycles 13 and 14, we expect the final
SLACS lens sample to number 80--100: an approximate doubling of the
number of known galaxy-scale strong gravitational lenses and an
order-of-magnitude increase in the number of optical Einstein rings.
By virtue of its homogeneous selection and sheer size, the SLACS
sample will allow an unprecedented exploration of the mass structure
of the early-type galaxy population as a function of all other
observable quantities. This new sample will be a valuable resource to
the astronomical community by enabling qualitatively new strong
lensing science, and as such we will waive all but a short {3-month}
proprietary period on the observations.

FGS 10989

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric
elements {perturbation orbit semi-major axis and inclination} of
extra-solar planets orbiting six stars. These companions were
originally detected by radial velocity techniques. We have
demonstrated that FGS astrometry of even a short segment of reflex
motion, when combined with extensive radial velocity information, can
yield useful inclination information {McArthur et al. 2004}, allowing
us to determine companion masses. Extrasolar planet masses assist in
two ongoing research frontiers. First, they provide useful boundary
conditions for models of planetary formation and evolution of
planetary systems. Second, knowing that a star in fact has a plantary
mass companion, increases the value of that system to future
extrasolar planet observation missions such as SIM PlanetQuest, TPF,
and GAIA.

NIC1 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 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

WFPC2 10745

WFPC2 CYCLE 14 INTERNAL MONITOR

This calibration proposal is the Cycle 14 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{both gain 7 and gain 15 -- to test stability of gains and bias
levels}, a test for quantum efficiency in the CCDs, and a monitor for
possible buildup of contaminants on the CCD windows. These also
provide raw data for generating annual super-bias reference files for
the calibration pipeline.

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 07 07
FGS REacq 08 08
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)