Daily # 4234

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4234

PERIOD COVERED: UT November 03,04,05, 2006 (DOY 307,308,309)

OBSERVATIONS SCHEDULED

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.

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.

NIC2 10893

Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble
Diagram

We propose building a high-z Hubble Diagram using type Ia supernovae
observed in the infrared rest-frame J-band. The infrared has a number
of exceptional properties. The effect of dust extinction is minimal,
reducing a major systematic tha may be biasing dark energy
measurements. Also, recent work indicates that type Ia supernovae are
true standard candles in the infrared meaning that our Hubble diagram
will be resistant to possible evolution in the Phillips relation over
cosmic time. High signal-to-noise measurements of 9 type Ia events at
z~0.4 will be compared with an independent optical Hubble diagram from
the ESSENCE project to test for a shift in the derived dark energy
equation of state due to a systematic bias. Because of the bright sky
background, H-band photometry of z~0.4 supernovae is not feasible from
the ground. Only the superb image quality and dark infrared sky seen
by HST makes this test possible. This experiment may also lead to a
better, more reliable way of mapping the expansion history of the
universe with the Joint Dark Energy Mission.

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.

ACS/WFC 10882

Emission Line 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. We
discovered new optical jets, dust lanes, and revealed point-like
nuclei whose properties support AGN unified schemes. Here, we propose
to obtain ACS emission line images at low and high excitation of 3CR
sources with z0.3, both low- and classical high- power radio
galaxies, as a major enhancement to an already superb dataset. We aim
to probe fundamental relationships between warm optical line-emitting
gas, radio source structure {jets and lobes} and X-ray coronal halos.
We will combine our existing UV images with new emission- line images
to establish quantitative star formation characteristics and their
relation to dust and merging, and with emission-line excitation maps,
test theories on ionization beam patterns and luminosities from active
nuclei. We will seek jet induced star formation and knowing optical
emission-line physics, investigate quantitative jet physics. The
nuclear emission line properties of the galaxies will themselves be
established and used as ingredients in continuing tests of unified AGN
theories. The resulting database will be an incredibly valuable
resource to the astronomical community for years to come.

ACS/HRC 10878

An ACS Prism Snapshot Survey for z~2 Lyman Limit Systems

We propose to conduct a spectroscopic survey of Lyman limit absorbers
at redshifts 1.7 z 2.2, using ACS/HRC and the PR200L prism. We
have selected 100 quasars at 2.3 z 2.6 from the Sloan Digital Sky
Survey Spectroscopic Quasar sample, for which no BAL signature is
found at the QSO redshift and no strong metal absorption lines are
present at z 2.3 along the lines of sight. The survey has three main
observational goals. First, we will determine the redshift frequency
dN/dz of the LLS over the column density range 16.3 log N_HI 20.3
cm^-2. Second, we will measure the column density frequency
distribution f{N} for the partial Lyman limit systems {PLLS} over the
column density range 16.3 log N_HI 17.5 cm^-2. Third, we will
identify new sightlines for measurements of the primordial D/H ratio.
With this survey, we will also constrain two key quantities of
cosmological relevance: First, the measurements of dN/dz for optically
thick LLS and f{N} for the PLLS are critical to estimating the
attenuation of extragalactic ionizing sources {e.g. QSOs}. Currently,
uncertainties in dN/dz and f{N} are the greatest sources of
uncertainty for inferring the shape and intensity of the UV background
radiation field. Second, we will estimate the amount of metals in the
LLS using the f{N} and ground based observations of metal line
transitions. It is possible that a significant fraction of the
"missing metals" at z~2 are associated with these highly ionized
absorbers. Third, analysis of the LLS lends to investigations of the
interface between galaxies {i.e. the damped Lyman alpha systems} and
the intergalactic medium {i.e. the Lyman alpha forest}. This survey is
ideal for a snapshot observing program, because the on-object
integration times are less than 10 minutes, and the targets cover the
majority of the northern sky.

ACS/HRC 10877

A Snapshot Survey of the Sites of Recent, Nearby Supernovae

During the past few years, robotic {or nearly robotic} searches for
supernovae {SNe}, most notably our Lick Observatory Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite nearby
galaxies {cz 4000 km/s}. Most of the objects were discovered before
maximum brightness, and have follow-up photometry and spectroscopy;
they include some of the best-studied SNe to date. We propose to
conduct a snapshot imaging survey of the sites of some of these nearby
objects, to obtain late-time photometry that {through the shape of the
light and color curves} will help reveal the origin of their lingering
energy. The images will also provide high-resolution information on
the local environments of SNe that are far superior to what we can
procure from the ground. For example, we will obtain color-color and
color-magnitude diagrams of stars in these SN sites, to determine the
SN progenitor masses and constraints on the reddening. Recovery of the
SNe in the new HST images will also allow us to actually pinpoint
their progenitor stars in cases where pre- explosion images exist in
the HST archive. This proposal is an extension of our successful Cycle
13 snapshot survey with ACS. It is complementary to our Cycle 15
archival proposal, which is a continuation of our long-standing
program to use existing HST images to glean information about SN
environments.

ACS/HRC 10860

The largest Kuiper belt object

The past year has seen an explosion in the discoveries of Pluto-sized
objects in the Kuiper belt. With the discoveries of the
methane-covered 2003 UB313 and 2005 FY9, the multiple satellite system
of 2003 EL61, and the Pluto-Charon analog system of Orcus and its
satellite, it is finally apparent that Pluto is not a unique oddball
at the edge of the solar system, but rather one of a family of
similarly large objects in the Kuiper belt and beyond. HST
observations over the past decade have been critical for understanding
the interior, surface, and atmosphere of Pluto and Charon. We propose
here a comprehensive series of observations designed to similarly
expand our knowledge of these recently discovered Pluto-sized and
near-Pluto-sized Kuiper belt objects. These observations will measure
objects' sizes and densities, explore the outcome of collisions in the
outer solar system, and allow the first ever look at the interior
structure of a Kuiper belt object. Our wide field survey that
discovered all of these objects is nearly finished, so after five
years of continuous searching we are finally almost complete in our
tally of these near-Pluto-sized objects. This large HST request is the
culmination of this half-decade search for new planetary-sized
objects. As has been demonstrated repeatedly by the approximately 100
previous orbits devoted to the study of Pluto, only HST has the
resolution and sensitivity for detailed study of these distant
objects.

ACS/HRC 10853

M82 as a Fossil Starburst: Probing the Super Star Cluster Content of
Region B

The importance of M82 as a benchmark for starburst studies has been
recognised by the STScI- sponsored ACS/WFC mosaic of M82 in the B, V,
I and H alpha filters. This proposal supplements this unique legacy
dataset by obtaining U-band observations {F330W filter} of the fossil
starburst region B in M82. This region is rich in compact intermediate
age {~ 1 Gyr} star clusters. The combination of U-band photometry with
the ACS/WFC STScI BVI survey and archival NICMOS JH data will allow us
to derive accurate ages, luminosities and masses for this rare
population of intermediate age massive star clusters. The U-band is
essential for determining ages of clusters 2 Gyr old because it
measures the depth of the Balmer jump. We will use these data to
determine the true shape of the cluster luminosity function {CLF} for
the M82-B fossil starburst region and thus address the question of
whether young massive clusters will eventually become globular
clusters.

NIC2 10849

Imaging Scattered Light from Debris Disks Discovered by the Spitzer
Space Telescope around 21 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 {IR} emission with the Spitzer Space Telescope
as part of the Spitzer Legacy Science program titled "The Formation
and Evolution of Planetary Systems" {FEPS, P.I.: M.Meyer}. Modeling of
the thermal excess emission from the spectral energy distributions
alone cannot distinguish between narrowly confined high-opacity disks
and broadly distributed, low-opacity disks. By resolving light
scattered by the circumstellar material, our proposed NICMOS
observations can break this degeneracy, thus revealing the conditions
under which planet formation processes are occuring or have occured.
For three of our IR-excess stars that have known radial-velocity
planets, resolved imaging of the circumstellar debris disks may
further offer an unprecedented view of planet-disk interactions in an
extrasolar planetary system. Even non-detections of the light
scattered by the circumstellar material will place strong constraints
on the disk geometries, ruling out disk models with high optical
depth. Unlike previous disk imaging programs, our program contains a
well-defined sample of ~1 solar mass stars covering a range of ages
from 3 Myr to 3 Gyr, thus allowing us to study the evolution of disks
from primordial to debris for the first time. The results from our
program will greatly improve our understanding of the architecture of
debris disks around Sun-like stars, and will create a morphological
context for the existence of our own solar system. This proposal is
for a continuation of an approved Cycle 14 program {GO/10527, P.I.: D.
Hines}.

ACS/WFC 10813

MgII Absorption Line Systems: Galaxy Halos or the Metal-Enriched IGM?

MgII QSO absorption lines detected in the spectra of background QSOs
were used over a decade ago to infer that all redshift z 0.2
galaxies have gaseous halos of radius ~ 60 kpc. The actual size of the
halo was believed to be proportional to the luminosity of the galaxy.
However, these conclusions are now much harder to understand in light
of the results from numerical simulations which show how gas evolves
in the universe. These models predict that gas and galaxies merely
share the same filamentary structures defined by dark matter. If these
models are correct, how are MgII systems and galaxies really related?
We can better understand the distribution of absorbing gas if we FIRST
select galaxies close to QSO sightlines and THEN search for MgII
absorption at the redshift of the intervening galaxies. This is the
antithesis of the original experiments which sought to find absorbing
galaxies based on known MgII systems. The frequency with which we
detect MgII lines from randomly selected galaxies should enable us to
better understand if absorption arises in the halos of individual
galaxies, or if MgII merely arises in the same IGM that galaxies
inhabit. We have used ground-based telescopes to indentify twenty z =
0.31-0.55 galaxies within 14-51 kpc of a g 20 QSO, and to search for
MgII absorption at the galaxies' redshifts. Surprisingly, we find that
only 50% of our QSOs show MgII absorption. In this proposal, we seek
multi-color ACS images of twelve of the fields to i} correlate the
incidence of MgII with galaxy morphology; ii} determine if absorption
{or lack thereof} is related to galaxy disks or halos; iii} search for
signs of galaxy interactions which may explain the large
cross-sections of MgII systems; and iv} look for faint interloping
galaxies closer to the line of sight than the one we identified. An
important component of the program is to observe each field in the
SDSS g-, r- and i-bands, to permit an estimate of the photometric
redshift of any objects which lie closer to the QSO sightline than the
identified galaxy, and which might actually be responsible for the
absorption.

ACS/HRC 10801

Direct Determination of Kuiper Belt Object Diameters with HST

When it comes to fundamental properties of an astronomical object, it
is difficult to think of a more fundamental physical property than its
size. Because of their distance, objects in the Kuiper Belt are
generally too small for their disks to be resolved. The heterogeneous
albedo and color of the Kuiper Belt population makes size estimates
from observed absolute magnitude highly uncertain. And the
long-awaited data from the Spitzer Space Telescope suffers from our
ignorance of crucial macro- and micro-physical properties such as spin
period, pole orientation, surface roughness, and thermal inertia. We
propose to add a new dimension to the measurement of KBO diameters by
employing two techniques that will directly measure the diameters of
three large KBOs. We expect to obtain diameter measurements with
uncertainties of 10% or better and utilize these to validate and cross
calibrate the growing web of diameter measurements for KBOs.

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/WFC 10758

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 May, 31 2006- Oct, 1-2006. The
first half of the program has a different proposal number: 10729.

ACS/WFC 10703

Life in the fast lane: The dark-matter distribution in the most
massive galaxy clusters in the Universe at z0.5

We propose two-filter ACS observations of a complete sample of 12 very
X-ray luminous galaxy clusters at 0.5z0.7 as a cornerstone of a
comprehensive multi-wavelength study of the properties of the most
massive clusters in the universe. Our sample includes the famous
systems Cl0016+16 and MS0451-03; all other clusters are new
discoveries from the MACS survey. Being the counterparts of the
best-studied systems at lower and higher redshift and comprising ALL
massive clusters at 0.5z0.7 observable from Mauna Kea this sample
will become the ultimate reference for cluster studies at z0.5. HST's
unique capabilities will allow us to: 1} measure accurately the
clusters' dark matter distribution on scales from tens to more than
500/h_50 kpc from observations of strong and weak gravitational
lensing, 2} use galaxy-galaxy lensing to measure the shape, extent,
and mass content of the dark-matter halos of both cluster and field
galaxies, and 3} study the color morphology of mergers and the star
formation history of galaxies in a high-density environment. The
proposed observations are complemented by Chandra observations of all
our targets {all 12 awarded, 11 executed to date} which provide
independent constraints on the dark matter and gas distribution in the
cluster cores, as well a by extensive groundbased observations of weak
lensing on yet larger scales, galaxy dynamics, and the SZ effect.

ACS/WFC/NIC3 10632

Searching for galaxies at z6.5 in the Hubble Ultra Deep Field

We propose to obtain deep ACS {F606W, F775W, F850LP} imaging in the
area of the original Hubble Ultra Deep Field NICMOS parallel fields
and - through simultaneous parallel observations - deep NICMOS {F110W,
F160W} imaging of the ACS UDF area. Matching the extreme imaging depth
in the optical and near-IR bands will result in seven fields with
sufficiently sensitive multiband data to detect the expected typical
galaxies at z=7 and 8. Presently no such a field exist. Our combined
optical and near-IR ultradeep fields will be in three areas separated
by about 20 comoving Mpc at z=7. This will allow us to give a first
assessment of the degree of cosmic variance. If reionization is a
process extending over a large redshift interval and the luminosity
function doesn't evolve strongly beyond z=6, these data will allow us
to identify of the order of a dozen galaxies at 6.5z8.5 - using the
Lyman break technique - and to place a first constrain on the
luminosity function at z6.5. Conversely, finding fewer objects would
be an indication that the bulk of reionization is done by galaxies at
z=6. By spending 204 orbits of prime HST time we will capitalize on
the investment of 544 prime orbits already made on the Hubble Ultra
Deep Field {UDF}. We have verified that the program as proposed is
schedulable and that it will remain so even if forced to execute in
the 2-gyro mode. The data will be non-proprietary and the reduced
images will be made public within 2 months from the completion of the
observations.

ACS/WFC 10588

The Host Galaxies of Post-Starburst Quasars

We propose to use ACS to conduct a snapshot imaging survey of
post-starburst quasars now being discovered in signficant numbers by
the Sloan Digital Sky Survey. Post-starburst quasars are broad-lined
AGN that also possess Balmer jumps and high-n Balmer absorption lines
indicative of luminous stellar populations on order of 100 Myr old.
These objects, representing a few percent of the z 0.5 quasar
population, may be an evolutionary stage in the transition of
ultraluminous infrared galaxies into normal quasars, or a type of
galaxy interaction that triggers both star formation and nuclear
activity. These sources may also illustrate how black hole mass/bulge
mass correlations arise. Ground-based imaging of individual
poststarburst quasars has revealed merger remnants, binary systems,
and single point sources. Our ACS snapshots will enable us to
determine morphologies and binary structure on sub-arcsecond scales
{surely present in the sample}, as well as basic host galaxy
properties. We will be looking for relationships among morphology,
particularly separation of double nuclei, the starburst age, the
quasar black hole mass and accretion rate, that will lead to an
understanding of the triggering activity and mutual evolution. This
project will bring quantitative data and statistics to the previously
fuzzy and anecdotal topic of the "AGN-starburst connection" and help
test the idea that post-starburst quasars are an early evolutionary
stage of normal quasars.

ACS/WFC 10551

Gamma-Ray Bursts from Start to Finish: A Legacy Approach

The progenitors of long-duration GRBs are now known to be massive
stars. This result lends credence to the collapsar model, where a
rotating massive star ends its life leaving a black hole or a highly
magnetized neutron star, and confirms its essential aspects. The focus
of attention now is on the black hole or magnetar engines that power
the bursts. Somehow these engines create the most highly relativistic
and highly collimated outflows that we know of, through mechanisms
that no current theory can explain. These astrophysical laboratories
challenge our understanding of relativistic shocks, of mechanisms for
extracting energy from a black hole, and of how physics works in
extreme conditions. The launch of Swift is bringing us into a new era,
where we can make broadband observations that will enable us to study
these fascinating physical processes. We propose here an ambitious,
comprehensive program to obtain the datasets that will become the
standard that any successful model for the central engine must
explain. This programs leverages the HST observations to the maximum
extent by our commitment of Swift observations, a Large program at the
VLA, and extensive ground-based optical resources. By studying the
engines and searching for jets in a variety of events, this program
will investigate the conditions necessary for the engine and jet
formation itself.

ACS/HRC 10508

Orbits, Masses, and Densities of Three Transneptunian Binaries

The subset of transneptunian objects {TNOs} having natural satellites
offers unique opportunities for physical studies of these distant
relics from the outer parts of the protoplanetary nebula. HST/ACS is
ideally suited to determining orbits of TNO satellites, resulting in
the system masses. In conjunction with thermal emission observations
by Spitzer, which provides sizes, we can determine the densities of
TNOs. Densities offer a powerful window into their bulk compositions
and interior structures.

ACS/WFC/NIC2 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.

ACS/WFC 10494

Imaging the mass structure of distant lens galaxies

The surface brightness distribution of extended gravitationally lensed
arcs and Einstein rings contains super-resolved information about the
lensed object, and, more excitingly, about the smooth and clumpy mass
distribution of the lens galaxies. The source and lens information can
non-parametrically be separated, resulting in a direct
"gravitational-mass image" of the inner mass-distribution of
cosmologically-distant galaxies {Koopmans 2005}. With this goal in
mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W imaging of
15 gravitational-lens systems with spatially resolved lensed sources,
selected from the 17 new lens systems discovered by the Sloan Lens ACS
Survey {Bolton et al. 2004}. Each system has been selected from the
SDSS and confirmed in a time-efficient HST-ACS snapshot program
{cycle-13}; they show highly-magnified arcs or Einstein rings, lensed
by a massive early-type lens galaxy. High- fidelity multi-color HST
images are required {not delivered by the 420-sec snapshot images} to
isolate these lensed images {properly cleaned, dithered and
extinction-corrected} from the lens galaxy surface brightness
distribution, and apply our "gravitational-mass imaging" technique.
The sample of galaxy mass distributions - determined through this
method from the arcs and Einstein ring HST images - will be studied
to: {i} measure the smooth mass distribution of the lens galaxies
{Dark and luminous mass are separated using the HST images and the
stellar M/L values derived from a joint stellar-dynamical analysis of
each system}; {ii} quantify statistically and individually the
incidence of mass-substructure {with or without obvious luminous
counter- parts such as dwarf galaxies}. Since dark-matter substructure
should be considerably more prevalent at higher redshift, both results
provide a direct test of this prediction of the CDM hierarchical
structure-formation model.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10493 - Reacq(1,2,2) resulted in Fine Lock Backup (1,0,1)

REacq scheduled at 307/10:10:41 resulted in fine lock backup on FGS1.
Mnemonics QF2STOPF and QSTOP were the only telemetry out of limit
indications. OBAD1: V1 5.01, V2 -38.43, V3 -0.79 RSS 38.76 OBAD2: V1
-4.77, V2 -8.73, V3 0.09 RSS 9.95

10494 - Reacq(1,2,2) failed to RGA Hold Control

Upon acquisition of signal at 307/11:46:34, REacq(1,2,2) scheduled at
307/11:46:34 - 11:54:39 was observed to have failed to RGA Hold due to
stop flags (QF1STOPF) and (QF2STOPF) on FGSs 1 and 2. Pre-acquisition
OBADs had attitude error corrections (RSS) values of 14.19 and 10.98
arcseconds. Post-acquisition OBAD/MAP not scheduled.

REacq(1,2,2) scheduled at 307/13:22:29 resulted in finelock backup
(1,0,1) using FGS-1 due to stop flag (QF2STOPF) on FGS-2.
Pre-acquisition OBADs had (RSS) values of 1769.27 and 12.67
arcseconds.

10495 - Reacq(2,1,2) Failed due to Search Radius Limit Exceeded

REacq(2,1,2) failed due to search radius limit exceeded for FGS 2. 1st
OBAD V1 -71.46, V2 384.78, V3 -27.53, RSS 392.33 2nd OBAD V1 13.69, V2
0.23, V3 7.27, RSS 15.50

10496 - REAcq(2,1,2) Failed to RGA control

At 308/13:38:36 REAcq (2,1,2) scheduled from 13:30:42-13:37:53 had
failed at RGA control. Due to LOS the only data received was from
308/13:37:04 till failure. No flags were noted. One 486 ESB "1805 -
FHST Moving Target Detected" was received at AOS (308/13:37:04).
Pre-Acquisition OBADs showed RSS values of 3253.83 & 98.78 a-s. Post
acquisition OBAD MAP showed RSS value of 7.63 a-s. Further information
is unavailable till an engineering data dump has been performed.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 26 26
FGS REacq 16 13
OBAD with Maneuver 80 80

SIGNIFICANT EVENTS: (None)