Daily #3995

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3995

PERIOD COVERED: UT November 23,24,25,26,27, 2005 (DOY 327,328,329,330,331)

OBSERVATIONS SCHEDULED

NICMOS 8791

NICMOS Post-SAA calibration - CR Persistence Part 2

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.

ACS/WFC/HRC/S/C 10771

CTE and QE measurement for ACS CCDs at three different temperatures

The goal of this program is to characterize the variation in CTE and
QE for the ACS/WFC and ACS/HRC CCDs when operated at temperatures
colder and warmer than the current operational temperature. The range
of temperature tested here should represent the coldest and warmest
temperature at which the CCD can be operated after SM4 in the case the
ASCS is installed or not installed {or installed and not connected to
ACS}.

ACS/HRC 10738

Earth Flats

Sky flats will be obtained by observing the bright Earth with the HRC
and WFC. These observations will be used to verify the accuracy of the
flats currently in the pipeline and to monitor any changes. Weekly
coronagraphic monitoring is required to assess the changing position
of the spots.

ACS/HRC/WFC 10737

CCD Stability Monitor

This program will verify that the low frequency flat fielding, the
photometry, and the geometric distortion are stable in time and across
the field of view of the CCD detectors. A moderately crowded stellar
field in the cluster 47 Tuc is observed every three months with the
HRC {at the cluster core} and WFC {6' West of the cluster core} using
the full suite of broad and narrow band imaging filters. The positions
and magnitudes of objects will be used to monitor local and large
scale variations in the plate scale and the sensitivity of the
detectors and to derive an independent measure of the detector CTE. An
additional orbit is required to compare WFC observations taken at gain
1 with those taken at the new default gain 2.

ACS/HRC/WFC 10733

CCD Hot Pixel Annealing

Hot pixel annealing will continue to be performed once every 4 weeks.
The CCD TECs will be turned off and heaters will be activated to bring
the detector temperatures to about +20C. This state will be held for
approximately 6 hours, after which the heaters are turned off, the
TECs turned on, and the CCDs returned to normal operating condition.
To assess the effectiveness of the annealing, a bias and four dark
images will be taken before and after the annealing procedure for both
WFC and HRC. The HRC darks are taken in parallel with the WFC darks.
The charge transfer efficiency {CTE} of the ACS CCD detectors declines
as damage due to on-orbit radiation exposure accumulates. This
degradation has been closely monitored at regular intervals, because
it is likely to determine the useful lifetime of the CCDs. We combine
the annealling activity with the charge transfer efficiency monitoring
and also merge into the routine dark image collection. To this end,
the CTE monitoring exposures have been moved into this proposal . All
the data for this program is acquired using internal targets {lamps}
only, so all of the exposures should be taken during Earth occultation
time {but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

ACS/HRC/WFC 10729

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. Changes from cycle 13:- The default
gain for WFC is 2 e-/DN. As before bias frames will be collected for
both gain 1 and gain 2. Dark frames are acquired using the default
gain {2}. This program cover the period Oct, 2 2005- May, 29-2006. The
second half of the program has a different proposal number: 10758.

NIC3 10702

The COSMOS 2-Degree ACS Survey NICMOS Parallels

The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a
companion to program 10092.

ACS/WFC 10626

A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to
z = 0.9

We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy
clusters at 0.3 z 0.9 from the Red Sequence Cluster Survey {RCS}.
An examination of the galaxian light in the brightest cluster
galaxies, coupled with a statistical analysis of the strong-lensing
properties of the sample, will allow us to contrain the evolution of
both the baryonic and dark mass in cluster cores, over an
unprecedented redshift range and sample size. In detail, we will use
the high- resolution ACS images to measure the metric {10 kpc/h}
luminosity and morphological disturbances around the brightest
clusters galaxies, in order to calibrate their accretion history in
comparison to recent detailed simulations of structure formation in
cluster cores. These images will also yield a well-defined sample of
arcs formed by strong lensing by these clusters; the frequency and
detailed distribution {size, multiplicity, redshifts} of these strong
lens systems sets strong constraints on the total mass content {and
its structure} in the centers of the clusters. These data will also be
invaluable in the study of the morphological evolution and properties
of cluster galaxies over a significant redshift range. These analyses
will be supported by extensive ongoing optical and near-infrared
imaging, and optical spectroscopy at Magellan, VLT and Gemini
telescopes, as well as host of smaller facilities.

FGS 10613

Calibrating the Mass-Luminosity Relation at the End of the Main
Sequence

We propose to use HST-FGS1R to calibrate the mass-luminosity relation
{MLR} for stars less massive than 0.2 Msun, with special emphasis on
objects near the stellar/brown dwarf border. Our goals are to
determine M_V values to 0.05 magnitude, masses to 5 than double the
number of objects with masses determined to be less than 0.20 Msun.
This program uses the combination of HST-FGS3/FGS1R at optical
wavelengths and ground-based infrared interferometry to examine
nearby, subarcsecond binary systems. The high precision measurements
with HST-FGS3/FGS1R {to 1 mas in the separations} for these faint
targets {V = 10--15} simply cannot be equaled by any ground based
technique. As a result of these measurements, we are deriving high
quality luminosities and masses for the components in the observed
systems, and characterizing their spectral energy distributions from
0.5 to 2.2 Mum. Several of the objects included have M 0.1 Msun,
placing them at the very end of the stellar main sequence. Three of
the targets are brown dwarf candidates, including the current low mass
record holder, GJ 1245C, with a mass of 0.062 +/- 0.004 Msun. The
payoff of this proposal is high because all 10 of the systems selected
have already been resolved with HST- FGS3/FGS1R during Cycles 5--10
and contain most of the reddest objects for which masses can be
determined.

FGS 10610

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.

ACS/HRC 10606

Ultraviolet Snapshots of 3CR Radio Galaxies

Radio galaxies are an important class of extragalactic objects: they
are one of the most energetic astrophysical phenomena and they provide
an exceptional probe of the evolving Universe, lying typically in high
density regions but well-represented across a wide redshift range. In
earlier Cycles we carried out extensive HST observations of the 3CR
sources in order to acquire a complete and quantitative inventory of
the structure, contents and evolution of these important objects.
Amongst the results, we discovered new optical jets, dust lanes,
face-on disks with optical jets, and revealed point-like nuclei whose
properties support FR-I/BL Lac unified schemes. Here, we propose to
obtain ACS NUV images of 3CR sources with z0.3 as a major enhancement
to an already superb dataset. We aim to reveal dust in galaxies,
regions of star and star cluster formation frequently associated with
dust and establish the physical characteristics of the dust itself. We
will measure frequency and spectral energy distributions of point-like
nuclei, seek spectral turnovers in known synchrotron jets and find new
jets. We will strongly test unified AGN schemes and merge these data
with existing X-ray to radio observations for significant numbers of
both FR-I and FR-II sources. The resulting database will be an
incredibly valuable resource to the astronomical community for years
to come.

ACS/WFC 10587

Measuring the Mass Dependence of Early-Type Galaxy Structure

We propose two-color ACS-WFC Snapshot observations of a sample of 118
candidate early- type gravitational lens galaxies. Our lens-candidate
sample is selected to yield {in combination with earlier results} an
approximately uniform final distribution of 40 early-type strong
lenses across a wide range of masses, with velocity dispersions {a
dynamical proxy for mass} ranging from 125 to 300 km/s. The proposed
program will deliver the first significant sample of low-mass
gravitational lenses. All of our candidates have known lens and source
redshifts from Sloan Digital Sky Survey data, and all are bright
enough to permit detailed photometric and stellar- dynamical
observation. We will constrain the luminous and dark-matter mass
profiles of confirmed lenses using lensed-image geometry and
lens-galaxy structural/photometric measurements from HST imaging in
combination with dynamical measurements from spatially resolved
ground-based follow-up spectroscopy. Hence we will determine, in
unprecedented detail, the dependence of early-type galaxy mass
structure and mass-to-light ratio upon galaxy mass. These results will
allow us to directly test theoretical predictions for halo
concentration and star-formation efficiency as a function of mass and
for the existence of a cuspy inner dark- matter component, and will
illuminate the structural explanation behind the fundamental plane of
early-type galaxies. The lens-candidate selection and confirmation
strategy that we propose has been proven successful for high-mass
galaxies by our Cycle 13 Snapshot program {10174}. The program that we
propose here will produce a complementary and unprecedented lens
sample spanning a wide range of lens-galaxy masses.

ACS/WFC 10576

An ACS Imaging Survey of the Galaxies Hosting Strong Mg II Absorption

Strong MgII absorbers {with rest-frame absorption equivalent width
W_MgII 0.3 A} at redshift z 1 are known to arise in extended
gaseous halos around luminous galaxies. Detailed absorption line
studies based on high-solution spectra of background quasars yield
tight constraints on the metallicity, ionization state, and kinematics
of the gaseous clouds. But whether they originate in gas accreted from
surrounding satellite galaxies or outflows associated with active
starburst in the host galaxies remains unclear. We have recently
completed a search of the Sloan Digital Sky Survey data archive for
strong MgII absorbers and identified over 1000 new systems that are
previously unknown. A subset of these MgII absorbers with W_MgII 1.8
A exhibit extreme kinematics with velocity widths {exceeding 200 km/s}
in our follow-up echelle spectra. Their dynamics are consistent with
various scenarios that include gas accretion {with speeds exceeding
the virial velocity} and starburst outflows {possibly driven by recent
merger events}. Independent of their exact nature, it is clear that
strong MgII systems serve as signposts to galactic halos with extreme
gas dynamics. Here we propose to conduct a snapshot survey of galaxies
in the fields toward high-redshift quasars with known, strong MgII
absorbers at 0.5 z 2. We plan to obtain high spatial-resolution
ACS/WFC images of 60 fields to uncover galaxies fainter than L* at the
redshifts of these absorbers and study their morphology. We will
complement the HST observations with follow-up spectroscopic
observations and IR images acquired at the Keck and Magellan
Observatories to for redshift identifications and for measuring
broad-band colors. We will investigate the correlation between
absorption line kinematics and galaxy morphology. In particular, we
will address whether on-going mergers is responsible for the extreme
dynamics observed in MgII absorption based on their rest-frame
ultraviolet morphology.

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/HRC/WFC 10548

Near-UV Snapshot Survey of Low Luminosity AGNs

Low-luminosity active galactic nuclei {LLAGNs} comprise ~30% of all
bright galaxies {B12.5} and are the most common type of AGN. These
include low-luminosity Seyfert galaxies, LINERs, and transition-type
objects {TOs, also called weak-[OI] LINERs}. What powers them is still
at the forefront of AGN research. To unveil the nature of the central
source we propose a near-UV snapshot survey of 50 nearby LLAGNs using
ACS/HRC and the filter {F330W}, a configuration which is optimal to
detect faint star forming regions around their nuclei. These images
will complement optical and near-IR images available in the HST
archive, providing a panchromatic atlas of the inner regions of these
galaxies, which will be used to study their nuclear stellar
population. Our main goals are to: 1} Investigate the presence of
nuclear unresolved sources that can be attributed to an AGN; 2}
Determine the frequency of nuclear and circumnuclear stellar clusters,
and whether they are more common in Transition Objects {TOs} than in
LINERs; 3} Characterize the sizes, colors, luminosities, masses and
ages of these clusters; 4} Derive the luminosity function of star
clusters and study their evaporation over time in the vicinity of
AGNs. Finally, the results of this project will be combined with those
of a previous similar one for Seyfert galaxies in order to compare the
nature of the nuclear sources and investigate if there could be an
evolution from Seyferts to TOs and LINERs. By adding UV images to the
existing optical and near-IR ones, this project will also create an
extremely valuable database for astronomers with a broad range of
scientific interests.

ACS/WFC/NIC3 10541

Probing the jet mattter content of quasar PKS 0637-752

The matter content {electron-proton vs electron-positron composition}
of extragalactic jets remains unknown, despite over three decades of
work. Here, we propose NICMOS/NIC3 and ACS observations of the
Chandra-detected, one sided jet of the superluminal quasar PKS 0637-
752 to derive the jet matter content by measuring the component of the
Cosmic Microwave Background {CMB} radiation that is bulk-Comptonized
{BC} by the cold electrons in the relativistically flowing large scale
jet. What makes this source particularly suited for this procedure, is
the absence of significant non-thermal jet emission from the 'bridge',
the region between the core and the first bright knot WK7.8,
guaranteeing that most of the electrons in the bridge are cold,
leaving the BC scattered CMB radiation as the only significant source
of photons in this region. The proposed NICMOS and ACS observations of
the knot WK7.8 will provide spectral information in the IR-UV regime,
which, together with existing multiwavelength data, will be used to
derive the jet Doppler factor and minimum power necessary to power the
knot emission as a function of the jet matter content. These will in
turn be used to deduce, or strongly constrain, the actual jet matter
content through comparison with the proposed NICMOS observations of
the BC 'bridge' emission.

NIC2 10540

Imaging Nearby Dusty Disks

Images of circumstellar debris disks around young stars display
complex structures that suggest they harbor forming planets. Disks
around stars of nearly the same age and mass show dramatically
different morphologies including rings with brightness asymmetries and
multiple warps. The reasons for this heterogeneity are not understood,
nor given the small sample of imaged disks, can we be sure we have yet
observed all possible outcomes of the planet formation process. Disk
imaging programs have demonstrated that the Hubble Space Telescope is
the only excellent platform for the high-contrast detection of
scattered light disks in the presence of their bright parent stars.
Therefore, we propose a NICMOS imaging survey of the nearest,
youngest, stars to Earth with substantial disks known from infrared
excess emission.

ACS/HRC 10539

Coronagraphic Imaging of Bright New Spitzer Debris Disks

Fifteen percent of bright main sequence stars possess dusty
circumstellar debris disks revealed by far-infrared photometry. These
disks are signposts of planetary systems: collisions among larger,
unseen parent bodies maintain the observed dust population against
losses to radiation pressure and P-R drag. Images of debris disks at
optical, infrared, and millimeter wavelengths have shown central
holes, rings, radial gaps, warps, and azimuthal asymmetries which
indicate the presence of planetary mass perturbers. Such images
provide unique insights into the structure and dynamics of
exoplanetary systems. Relatively few debris disks have been spatially
resolved. Only nine have ever been resolved at any wavelength, and at
wavelengths 10 microns {where subarcsec resolution is available},
only seven: beta Pictoris, HR 4796, HD 141569, AU Mic, HD 107146, HD
92945, and Fomalhaut. Imaging of many other debris disk targets has
been attempted with various HST cameras/coronagraphs and adaptive
optics, but without success. The key property which renders a debris
disk observable in scattered light is its dust optical depth. The
seven disks imaged so far all have a dust excess luminosity ~ 0.01%
that of the central star; no disks with smaller optical depths have
been detected. Most main sequence stars known to meet this requirement
have already been observed, so future progress in debris disk imaging
depends on discovering additional stars with large infrared excess.
The Spitzer Space Telescope offers the best opportunity in 20 years to
identify new examples of high optical depth debris disk systems. We
propose ACS coronagraphic imaging of nine bright, new debris disks
uncovered during the first year of the Spitzer mission. Our goal is to
obtain the first resolved images of these disks at ~3 AU resolution,
define the disk sizes and orientations, and uncover disk substructures
indicative of planetary perturbations. The results should double the
number of debris disks observed at 0.06" resolution, and open a wider
window into the structure of planetary systems.

NIC2 10527

Imaging Scattered Light from Debris Disks Discovered by the Spitzer
Space Telescope Around 20 Sun-like Stars

We propose to use the high contrast capability of the NICMOS
coronagraph to image a sample of newly discovered circumstellar disks
associated with sun-like stars. These systems were identified by their
strong thermal infrared emission with the Spitzer Space Telescope as
part of the Spitzer Legacy Science program titled, "The Formation and
Evolution of Planetary Systems {FEPS}." Modelling of the thermal
excess emission in the form of spectral energy distributions alone
cannot distinguish between narrowly confined high opacity disks and
broadly distributed, low opacity disks. However, our proposed NICMOS
observations can, by imaging the light scattered from this material.
Even non- detections will place severe constraints on the disk
geometry, ruling out models with high optical depth. Unlike previous
disk imaging programs, our program contains a well defined sample of
solar mass stars covering a range of ages from ~10Myrs to a few Gyrs,
allowing us to study the evolution of disks from primordial to debris
for the first time. These results will greatly improve our
understanding of debris disks around Sun- like stars at stellar ages
nearly 10x older than any previous investigation. Thus we will have
fit a crucial piece into the puzzle concerning the formation and
evolution of our own solar system.

ACS/WFC 10526

Dynamics of the Polarization Structure of the Crab Nebula

The Crab Nebula is not a free expansion SNR. Rather, it is a pulsar
wind nebula expanding from the inside out into a larger remnant of
freely expanding ejecta. At the heart of this object is the Crab
Pulsar and the region where the pulsar's highly nonisotropic wind
interacts with the larger synchtron nebula. HST and Chandra monitoring
has shown this to be one of the most intricately structured and highly
dynamical objects ever observed. In Cycle 12 we demonstrated our
ability to use the polarization capabilities of the ACS to isolate
physically discrete features within the Crab Synchrotron Nebula and
accurately measure their polarization characteristics. These data
provide a unique look at the physical structure in the heart of the
Crab, adding a new dimension to past observations. Polarization
provides extensive information about field geometries, the degree of
disorder in the field, and particle pitch angle distributions. But one
image of the Crab is like a single image of waves at the beach. It
necessarily misses the point. In the Crab, the name of the game is
"dynamics". In this proposal we request time to monitor changes in the
polarization structure of the Crab. This program will allow us to
follow the changing polarization of features including
relativistically moving wisps in the Crab Nebula. This is the only
place in the sky where a dynamic relativistic plasma can be observed
in sufficient detail to make such measurements possible, and the
HST/ACS is the only instrument that we are likely to see in our
careers capable of making the measurement. These observations will be
an important addition to the already rich observational legacy of HST
for what is arguably the most important single object in astrophysics.

ACS/HRC 10525

Characterizing the Near-UV Environment of M Dwarfs: Implications for
Extrasolar Planetary Searches and Astrobiology

We propose SNAP observations with the ACS HRC PR200L prism, designed
to measure the near ultraviolet emission in a sample of 107 nearby M
dwarfs. The sample spans the mass range from 0.1 - 0.6 solar masses
{temperature range 2200K - 4000K} where the UV energy distributions
vary widely between active and inactive stars. The strength and
distribution of this UV emission can have critical consequences for
the atmospheres of attendant planets. Our proposed observations will
provide desperately needed constraints on models of the habitability
zone and the atmospheres of possible terrestrial planets orbiting M
dwarf hosts, and will be used to sharpen TPF target selection. In
addition, the NUV data will be used in conjunction with existing
optical, FUV and X-ray data to constrain a new generation of M dwarf
atmospheric models, and to explore unanswered questions regarding the
dynamo generation and magnetic heating in these low-mass stars.

ACS/WFC 10524

Blue Stragglers: a key stellar population to probe internal cluster
dynamics

This proposal is part of a coordinated project devoted to understand
the interplay of globular cluster {GC} dynamics and the formation and
evolution of blue straggler stars {BSS}. By using a combination of HST
and ground-based observations we are constructing complete BSS surveys
in a sample of GCs; complete BSS surveys require mid-UV HST
observations in the center and wide field CCD ground based
observations under excellent seeing conditions of the exterior. Up to
now only four clusters have been surveyed in this way and the results
are surprising: in three GCs {M3, 47 Tuc, NGC 6752} we have discovered
that the BSS radial distribution is bimodal, highly peaked in the
cluster center, rapidly decreasing at intermediate radii and rising
again at large radii {Ferraro et al. 1997, 2004, Sabbi et al. 2004},
conversely BSS population in Omega Centauri does not show any
signature of the segregation which would be expected for a class of
objects arising from either stellar interactions or binarity {Ferraro
et al. 2005}. These observational facts are opening a new prospective
in the study of the formation processes and evolution of BSS in GCs.
By using extensive simulations, we demonstrated that the spatial
distribution of BSS observed in 47 Tuc can be only reproduced if a
sizable fraction of BSS is generated {via mass transfer in primordial
binaries} in the peripheral region of the cluster {Mapelli et al
2004}, thus excluding a purely collisional formation scenario. Here we
propose mid-UV imaging of a few clusters suspected of harboring a
large population of central BSS and a few known to have many BSS the
external region. These are good candidates for determining accurate
BSS radial distributions. The modest amount of time proposed here will
go far to determine the ubiquity of BSS bimodality and to constrain
models of dynamical evolution. Since we believe the proposed
observations would be useful to the entire stellar community {for
multifold purposes} we waive the propretary period.

ACS/HRC/WFC 10514

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 a
Snapshot program using the ACS/HRC that has a potential discovery
efficiency an order of magnitude higher than the HST observations that
have already discovered the majority of known transneptunian binaries.
By more than doubling the number of observed objects in dynamically
hot and cold subpopulations we will be able to answer, with
statistical significance, the question of whether these groups differ
in the abundance of binaries as a result 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/WFC 10505

The Onset of Star Formation in the Universe: Constraints from Nearby
Isolated Dwarf Galaxies.

The details of the early star formation histories of tiny dwarf
galaxies can shed light on the role in galaxy formation of the
reionization which occured at high redshift. Isolated dwarfs are ideal
probes since their evolution is not complicated by environmental
effects owing to the vicinity of the Milky Way and M31. In addition,
dwarf galaxies are the most common type of galaxies, and potentially
the building blocks of larger galaxies. Since we can date the oldest
stars in them, their study represents a complementary approach to the
study of the formation and evolution of galaxies through high-z
observations. We propose to use the ACS to obtain a homogeneus dataset
of high-quality photometry, down to the old {13 Gyr} main-sequence
turnoffs, for a representative sample of 4 isolated Local Group dwarf
galaxies. These data are essential to unambiguously determine their
early star formation histories, through comparison with synthetic
color-magnitude diagrams, and using the constraints provided by their
variable stars. Parallel WFPC2 observations of their halos will allow
us to reveal the actual nature of their stellar population gradients,
providing important aditional constraints on their evolution. The
proposed observations are being complemented with ground-based
spectroscopy, to obtain metallicity and kinematic information. The
observations requested here, which must reach M_I=+3.5 {I=27.5- 28.2}
with S/N=10 in crowded systems, can only be achieved with HST using
ACS, and won't be possible with planned ground- or space-based
facilities such as JWST. Based on deep WFPC2 observations and ACS
image simulations, our team has designed an observational strategy
which carefully considers the optimal filter combination, the
necessary photometry depth and the effects of stellar crowding.

ACS/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with
Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful
"dust free" Type Ia supernovae {SNe Ia} dataset than available with
the previous GOODS searches. Moreover, this approach provides a
strikingly more efficient search-and-follow-up that is primarily pre-
scheduled. The resulting dark energy measurements do not share the
major systematic uncertainty at these redshifts, that of the
extinction correction with a prior. By targeting massive galaxy
clusters at z 1 we obtain a five-times higher efficiency in
detection of Type Ia supernovae in ellipticals, providing a
well-understood host galaxy environment. These same deep cluster
images then also yield fundamental calibrations required for future
weak lensing and Sunyaev-Zel'dovich measurements of dark energy, as
well as an entire program of cluster studies. The data will make
possible a factor of two improvement on supernova constraints on dark
energy time variation, and much larger improvement in systematic
uncertainty. They will provide both a cluster dataset and a SN Ia
dataset that will be a longstanding scientific resource.

WFPC2 10481

HST Observations of Astrophysically Important Visual Binaries

This is a continuation of a project begun in Cycle 7 and continued up
through Cycle 11. The program consists of annual or biannual WFPC2 or
FGS observations of three visual binary stars that will ultimately
yield fundamental astrophysical results, once their orbits and masses
are determined. Our targets are the following: {1} Procyon {P = 41
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 excellent agreement with
theoretical evolutionary tracks 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 =
19 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 = 21 yr}, a famous metal-deficient G dwarf
for which accurate masses will lead to the stars' helium contents,
with cosmological implications.

ACS/HRC 10435

Merger-Induced Populations in Early-Type Galaxy Cores

Hierarchical formation models predict that early-type galaxies are
built up over an extended period from mergers of smaller systems, a
process which should leave long-lived signatures in their light
profiles and stellar population colors. Merger events should have
continued up to relatively recent times {the last 1-5 Gyr}, and many
ellipticals and S0 bulges should therefore show evidence of multiple,
discrete, intermediate-age populations. Although there is substantial
observational support for a dissipational merger origin for some
early-type galaxies, most do not exhibit the expected anomalies in
either their light profiles or color distributions. However, existing
searches {mainly in the V and I bands} have not probed very deeply.
Here we propose high resolution, broad-band, near-ultraviolet
{2500-3400 A} imaging of the cores of bright early- type galaxies.
This is the most sensitive probe available for the detection of
spatially-segregated, multiple population components with ages in the
range 1-5 Gyr. Our sample consists of dust- and AGN-free systems with
both normal and mildly anomalous central light profiles. There is very
little existing information on the near-UV structure of early-type
galaxies, and our program would effectively explore new terrain.

ACS/HRC 10396

Star Clusters, Stellar Populations, and the Evolution of the Small
Magellanic Cloud

As the closest star forming dwarf galaxy, the SMC is the preferred
location for detailed studies of this extremely common class of
objects. We therefore propose to use the capabilities of ACS, which
provide an improvement by an order of magnitude over what is possible
with ground- based optical imaging surveys that are limited by
confusion anddepth, to measure key stellar population parameters in
the SMC from VI color-magnitude diagrams. Our program focuses on
regions where crowding makes HST essential and includes 7 star
clusters and 7 field star locations. We will measure accurate ages of
the clusters, test stellar evolution models, gain fiducial stellar
sequences to use in fitting the field stars, check the form of the
IMF, and substantially extend the study of RR Lyrae variables in the
key NGC121 SMC globular cluster. The field pointings will allow us to
reconstruct the star formation history, look for enhanced star
formation that is expected when the SMC interacts with the LMC and/or
Milky Way, and compare its main sequence luminosity {and mass}
functions with those of the Milky Way, LMC, and UMi dwarf spheroidal.
This proposal is part of a coordinated HST and ground-based study of
the stellar history and star formation processes in the SMC.

NIC2 10173

Infrared Snapshots of 3CR Radio Galaxies

Radio galaxies are an important class of extragalactic objects: they
are one of the most energetic astrophysical phenomena and they provide
an exceptional probe of the evolving Universe, lying typically in high
density regions but well-represented across a wide redshift range. In
earlier Cycles we carried out extensive HST observations of the 3CR
sources in order to acquire a complete and quantitative inventory of
the structure, contents and evolution of these important objects.
Amongst the results, we discovered new optical jets, dust lanes,
face-on disks with optical jets, and revealed point-like nuclei whose
properties support FR-I/BL Lac unified schemes. Here, we propose to
obtain NICMOS infrared images of 3CR sources with z0.3 as a major
enhancement to an already superb dataset. We aim to deshroud dusty
galaxies, study the underlying host galaxy free from the distorting
effects of dust, locate hidden regions of star formation and establish
the physical characteristics of the dust itself. We will measure
frequency and spectral energy distributions of point-like nuclei,
expected to be stronger and more prevalent in the IR, seek spectral
turnovers in known synchrotron jets and find new jets. We will
strongly test unified AGN schemes and merge these data with existing
X-ray to radio observations. The resulting database will be an
incredibly valuable resource to the astronomical community for years
to come.

NIC1 10143

Ultracool companions to the nearest L dwarfs

We propose to conduct the most sensitive survey to date for low mass
companions to nearby L dwarfs. We will use NICMOS to image targets
drawn from a volume-complete sample of 70 L dwarfs within 20 parsecs.
The combination of infrared imaging and proximity will allow us to
search for T dwarf companions at separations as small as 1.6 AU. This
is crucial, since no ultracool binaries are currently known with
separations exceeding 15 AU. Only 10 dwarfs in this sample have
previous HST observations primarily at optical wavelengths. With the
increased sensitivity of our survey, we will provide the most
stringent test to date of brown dwarf models which envisage formation
as ejected stellar embryos. In addition, our observations will be
capable of detecting binaries with mass ratios as low as 0.3, and will
therefore also test the apparent preference for equal-mass ultracool
binaries. Finally, our observations offer the best prospect to date of
detecting companions significantly cooler than the coolest t dwarf
currently known.

ACS/WFC/WFPC2 10092

The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey -- COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble's ultimate
legacy for understanding the evolution of both the visible and dark
universe.

WFPC2 10772

WF4 Anomaly Characterization

A anomaly has been found in images from the WF4 CCD in WFPC2. The WF4
CCD bias level appears to have become unstable, resulting in sporadic
images with either low or zero bias level. The other three CCDs {PC1,
WF2, and WF3} appear to be unaffected and continue to operate
properly. The impacts from "low" and "zero" bias are somewhat
different, but in both cases the effects are immediately obvious. At
present there are still many images which appear fine and unaffected,
but the situation is quickly evolving. We believe the science impact
for most observers will be minimal. Targets are by default placed on
either PC1 or WF3 which continue to operate properly. However,
observers requiring the full field of view {survey projects, large
targets, etc.} will potentially lose one-third of their imaging area.
Our understanding of this anomaly is still evolving, and most of the
information is tentative.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10023 - GSAcq (2,1,2) failed due to search radius limit exceeded on
FGS1 @ 328/0627z GSAcq scheduled for 328/06:24:34 failed due to search
radius limit exceeded. At 06:27:50 received 486 ESB A05
(Exceeded_SRL). Vehicle reverted to M2G control.

OBAD 1 @ 05:44:17 showed the following errors - V1 -1337.94, V2
-1768.35, V3 969.89, RSS 2420.30

OBAD 2 @ 06:18:10 showed the following errors - V1 4.74, V2 -4.08, V3
4.64, RSS 7.79

OBAD MAP @ 07:12:29 showed the following errors: V1 -57.03, V2
1862.90, V3 -24.65, RSS 1863.93

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS
GSacq 46 45 328/0627z
(HSTAR 10023)
FGS REacq 18 18
OBAD with Maneuver 128 128

SIGNIFICANT EVENTS: (None)