LoCuSS is a systematic and detailed investigation of the mass,
substructure, and thermodynamics of 100 X-ray luminous galaxy clusters
at 0.15<z<0.3. 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. We propose to
complete our successful Cycle 15 program {SNAP:10881} which prior to
premature termination had delivered robust weak-lensing detections in 17
clusters, and candidate strongly-lensed arcs in 11 of these 17. 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 {z>1}
cluster samples. To complete the all-important high resolution imaging
component of our survey, we request deep WFPC2 observations of 20
clusters through the F606W filter, for which wide-field weak-lensing
data are already available from our Subaru imaging program. The
combination of deep WFPC2 and Subaru data for these 20 clusters will
enable us to achieve the science program approved by the Cycle 15 TAC.

The role that massive stars play in the dust content of the Universe is
extremely uncertain. It has long been hypothesized that dust can
condense within the ejecta of supernovae {SNe}, however there is a
frustrating discrepancy between the amounts of dust found in the early
Universe, or predicted by nucleation theory, and inferred from SN
observations. Our SEEDS collaboration has been carefully revisiting the
observational case for dust formation by core-collapse SNe, in order to
quantify their role as dust contributors in the early Universe. As dust
condenses in expanding SN ejecta, it will increase in optical depth,
producing three simultaneously observable phenomena: {1} increasing
optical extinction; {2} infrared {IR} excesses; and {3} asymmetric
blue-shifted emission lines. Our SEEDS collaboration recently reported
all three phenomena occurring in SN2003gd, demonstrating the success of
our observing strategy, and permitting us to derive a dust mass of up to
0.02 solar masses created in the SN. To advance our understanding of the
origin and evolution of the interstellar dust in galaxies, we propose to
use HST's WFPC2 and NICMOS instruments plus Spitzer's photometric
instruments to monitor ten recent core- collapse SNe for dust formation
and, as a bonus, detect light echoes that can affect the dust mass
estimates. These space-borne observations will be supplemented by
ground- based spectroscopic monitoring of their optical emission line
profiles. These observations would continue our 2-year HST and Spitzer
monitoring of this phenomena in order to address two key questions: Do
all SNe produce dust? and How much dust do they produce? As all the SN
are witin 15 Mpc, each SN stands an excellent chance of detection with
HST and Spitzer and of resolving potential light echoes.

We propose HST FGS observations to measure accurate distances of 5
nearby M dwarf eclipsing binary systems, from which model-independent
luminosities can be calculated. These objects have either poor or no
existing parallax measurements. FGS parallax determinations for these
systems, with their existing dynamic masses determined to better than
0.5%, would serve as model-independent anchor points for the low-mass
end of the mass-luminosity diagram.

The current census of binaries among the massive O-type stars is
seriously incomplete for systems in the period range from years to
millennia because the radial velocity variations are too small and the
angular separations too close for easy detection. Here we propose to
discover binaries in this observational gap through a Faint Guidance
Sensor SNAP survey of relatively bright targets listed in the Galactic O
Star Catalog. Our primary goal is to determine the binary frequency
among those in the cluster/association, field, and runaway groups. The
results will help us assess the role of binaries in massive star
formation and in the processes that lead to the ejection of massive
stars from their natal clusters. The program will also lead to the
identification of new, close binaries that will be targets of long term
spectroscopic and high angular resolution observations to determine
their masses and distances. The results will also be important for the
interpretation of the spectra of suspected and newly identified binary
and multiple systems.

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in
the Magellanic Clouds centered on background quasars. We used these data
to determine the proper motions of the LMC and SMC to better than 5% and
15% respectively. These are by far the best determinations of the proper
motions of these two galaxies. The results have a number of unexpected
implications for the Milky Way-LMC-SMC system. The implied
three-dimensional velocities are larger than previously believed, and
are not much less than the escape velocity in a standard 10^12 solar
mass Milky Way dark halo. Orbit calculations suggest the Clouds may not
be bound to the Milky Way or may just be on their first passage, both of
which would be unexpected in view of traditional interpretations of the
Magellanic Stream. Alternatively, the Milky Way dark halo may be a
factor of two more massive than previously believed, which would be
surprising in view of other observational constraints. Also, the
relative velocity between the LMC and SMC is larger than expected,
leaving open the possibility that the Clouds may not be bound to each
other. To further verify and refine our results we now request an epoch
of WFPC2/PC data for the fields centered on 40 quasars that have at
least one epoch of ACS imaging. We request execution in snapshot mode,
as in our previous programs, to ensure the most efficient use of HST
resources. A third epoch of data of these fields will provide crucial
information to verify that there are no residual systematic effects in
our previous measurements. More importantly, it will increase the time
baseline from 2 to 5 yrs and will increase the number of fields with at
least two epochs of data. This will reduce our uncertainties
correspondingly, so that we can better address whether the Clouds are
indeed bound to each other and to the Milky Way. It will also allow us
to constrain the internal motions of various populations within the
Clouds, and will allow us to determine a distance to the LMC using
rotational parallax.

We propose to obtain repeat narrowband images of a sample of eighteen
planetary nebulae {PNe} which have HST/WFPC2 archival data spanning time
baselines of a decade. All of these targets have previous high
signal-to-noise WFPC2/PC observations and are sufficiently nearby to
have readily detectable expansion signatures after a few years. Our main
scientific objectives are {a} to determine precise distances to these
PNe based on their angular expansions, {b} to test detailed and highly
successful hydrodynamic models that predict nebular morphologies and
expansions for subsamples of round/elliptical and axisymmetric PNe, and
{c} to monitor the proper motions of nebular microstructures in an
effort to learn more about their physical nature and formation
mechanisms. The proposed observations will result in high-precision
distances to a healthy subsample of PNe, and from this their expansion
ages, luminosities, CSPN properties, and masses of their ionized cores.
With good distances and our hydro models, we will be able to determine
fundamental parameters {such as nebular and central star masses,
luminosity, age}. The same images allow us to monitor the changing
overall ionization state and to search for the surprisingly
non-homologous growth patterns to bright elliptical PNe of the same sort
seen by Balick & Hajian {2004} in NGC 6543. Non-uniform growth is a sure
sign of active pressure imbalances within the nebula that require
careful hydro models to understand.

We propose to conduct the first HST imaging of Asteroid 2 Pallas with
WFPC2-PC over 4 HST orbits. We will image the asteroid in five filters:
F336w, F439w, F555w, F675w and F814w. We will utilize these observations
to drastically improve the knowledge of Pallas' shape, spin pole
position and surface properties, including roughness and albedo,
parameters that are poorly determined by previous study. These
observations will result in high signal-to-noise, high resolution
surface maps from the visible to the UV. A satellite search will also be
conducted for objects within the stability field of up to 21st
magnitude, or about 900m in diameter. It is demonstrated in our proposal
that significant scientific opportunity exists in Cycle 16 because
Pallas is at both a low-phase, 3.9 degree opposition and near its
closest approach to Earth, conditions that do not occur simultaneously
in the next twenty years. This window represents the best chance to
answer long standing, fundamental questions about Pallas, the main
asteroid belt, and the formation of the solar system.

We propose to obtain deep color-magnitude data of eight new Local Group
galaxies which we recently discovered: Andromeda XI, Andromeda XII, and
Andromeda XIII {satellites of M31}; Canes Venatici I, Canes Venatici II,
Hercules, and Leo IV {satellites of the Milky Way}; and Leo T, a new
"free-floating" Local Group dwarf spheroidal with evidence for recent
star formation and associated H I gas. These represent the least
luminous galaxies known at *any* redshift, and are the only accessible
laboratories for studying this extreme regime of galaxy formation. With
deep WFPC-2 F606W and F814W pointings at their centers, we will
determine whether these objects contain single or multiple age stellar
populations, as well as whether these objects display a range of
metallicities.

The standard star GRW+70D5829 is observed in filter and chip
combinations that were not included in photometric calibration programs
from 2005, 2006, and 2007. These observations are needed to complete a
library of recent standard star observations taken in all filter and
chip combinations before WFPC2 is decommissioned in SM4. {Linear Ramp
and Polarizer filters are covered in a separate proposal.} These
observations, along with other recent standard star observations, will
be used to study long-term throughput.

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.

We propose to use HST's unique high spatial resolution imaging
capabilities to conclusively confirm or refute the presence of alleged
very young globular clusters in M31. Such young globular clusters with
ages < 3 Gyr are not present in our galaxy, and, if real, would lead to
a striking difference in the age distribution of the GCs between M31 and
the Milky Way. If the apparent presence of very young globular clusters
in M31 is confirmed through our proposed ACS imaging {now WFPC2 imaging}
with HST, this would suggest major differences in the history of
assembly of the two galaxies, with probable substantial late accretion
into M31 which did not occur in our own galaxy.

10897 - Unplanned HST communications outage
           HST experienced an unplanned communication outage beginning at about
          15:46 GMT on Friday, September 7. Communication was restored via LGAs at
          ~17:53 GMT following a telemetry switch to A-format (4kps). All
          spacecraft systems were verified nominal and communications were
          re-configured back to HST high-gain antennas. There were no hardware
          anomalies and normal science activities continued throughout the period
           without loss of science data.

           Analysis confirmed that the S/C communications equipment was left in
           coherent mode following a planned 2-way tracking event. This permitted
           capture of the HST MA transponder by a ground station overflight of the
           USN station at South Point, Hawaii. Per the hardware's design, detection
           of the ground signal by the HST transponder resulted in a transition to
           GSTDN-mode baseband RF signal. The two subsequent TDRSS passes were

COMPLETED OPS REQUEST: (None)