Daily Report #4487

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science
capability in January, there may be an occasional discrepancy between
a proposal's listed (and correct) instrument usage and the abstract
that follows it.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** # 4487

PERIOD COVERED: UT November 09,10,11,12, 2007 (DOY 313,314,315,316)

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 DARKs. 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 11312

The Local Cluster Substructure Survey {LoCuSS}: Deep Strong Lensing
Observations with WFPC2

LoCuSS is a systematic and detailed investigation of the mass,
substructure, and thermodynamics of 100 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.
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 {z1} 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.

WFPC2 11307

Completing the ACS Nearby Galaxy Survey with WFPC2

We are requesting 25 orbits of Director's Discretionary Time to
complete the primary science goals of our highly-ranked ACS Nearby
Galaxy Survey Treasury program {ANGST}. Our program lost ~2/3 of its
orbits due to the ACS failure. Roughly half of these were restored as
a result of an appeal to the Telescope Time Review Board which
re-scoped the program. The Board's response to our appeal was explicit
in terms of which targets were to be observed and how. We were
directed to request Director's discretionary time for the components
of the appeal which were not granted by the Review Board, but which
were vital to the success of the program. The observing strategy for
ANGST is two-fold: to obtain one deep field per galaxy which enables
derivation of an accurate ancient star formation history, and to
obtain radial tilings sufficient for recovering the full star
formation history. The Review Board granted WFPC2 observations for
deep fields in 7 galaxies, but no time for radial tilings. However,
recovering the full star formation history of a galaxy is not possible
without additional radial coverage. We have searched the archives for
observations which may be used in place of the tilings {conceding some
of the Treasury goals, but providing significant constraints on the
full star formation history}, and have identified suitable
observations for all but two of the galaxies. Here we request DD time
for radial tilings for those last two galaxies.

NIC3 11306

Direct radius measurement of the Neptune-size transiting exoplanet
GJ436b

We propose to measure the radius of the first transiting Neptune-class
extrasolar planet, GJ 436b. The transits of this 22-Earth-mass planet
around a nearby M dwarf were recently detected by our team.
Ground-based photometric observations indicate a planet size
compatible with a Neptune-like structure or an "Ocean Planet". A
direct radius determination from an HST infrared lightcurve will
provide a much more direct measurement of the radius and density of
the planet. GJ 436b is the nearest known transiting exoplanet, as well
as the smallest and lightest, by a large margin. The high
planet-to-star contrast in the infrared make it very favorable for
detailed studies. NICMOS 1-2 microns observations, in addition to
measuring its size, may reveal water absorption from its outer
atmosphere.

NIC2 11219

Active Galactic Nuclei in nearby galaxies: a new view of the origin of
the radio-loud radio- quiet dichotomy?

Using archival HST and Chandra observations of 34 nearby early-type
galaxies {drawn from a complete radio selected sample} we have found
evidence that the radio-loud/radio-quiet dichotomy is directly
connected to the structure of the inner regions of their host galaxies
in the following sense: [1] Radio-loud AGN are associated with
galaxies with shallow cores in their light profiles [2] Radio-quiet
AGN are only hosted by galaxies with steep cusps. Since the brightness
profile is determined by the galaxy's evolution, through its merger
history, our results suggest that the same process sets the AGN
flavour. This provides us with a novel tool to explore the
co-evolution of galaxies and supermassive black holes, and it opens a
new path to understand the origin of the radio-loud/radio-quiet AGN
dichotomy. Currently our analysis is statistically incomplete as the
brightness profile is not available for 82 of the 116 targets. Most
galaxies were not observed with HST, while in some cases the study is
obstructed by the presence of dust features. We here propose to
perform an infrared NICMOS snapshot survey of these 82 galaxies. This
will enable us to i} test the reality of the dichotomic behaviour in a
substantially larger sample; ii} extend the comparison between
radio-loud and radio-quiet AGN to a larger range of luminosities.

ACS/SBC 11215

New Sightlines for the Study of Intergalactic Helium: Dozens of
High-Confidence, UV-Bright Quasars from SDSS/GALEX

The reionization of IGM helium is thought to have occurred at
redshifts of z=3 to 4. Detailed study of HeII Lyman-alpha absorption
toward a handful of QSOs at 2.7z3.3 demonstrated the high potential
of such IGM probes, but the critically small sample size limits
confidence in cosmological inferences. The requisite unobscured
sightlines to high-z are extremely rare, but SDSS provides 5800, z3.1
QSOs potentially suitable for HeII studies. We've cross-correlated
SDSS quasars with GALEX UV sources to obtain dozens of new, high
confidence, candidate sightlines {z=3.1-4.9} potentially useful for
detailed HeII studies with HST. We propose brief, 2-orbit
reconnaissance ACS SBC prism exposures toward each of the best dozen
new quasars, to definitively verify UV flux down to HeII. Our combined
SDSS/GALEX selection insures a high confirmation rate, as the quasars
are already known to be UV bright in GALEX. Our program will provide a
statistical sample of HeII sightlines extending to high redshift,
enabling future long exposure follow-up spectra with the SBC prism, or
superb quality COS or STIS spectra after SM4. Stacks of our prism
spectra will also directly yield ensemble information. Ultimately, the
new sightlines will enable confident measures of the spectrum and
evolution of the ionizing background, the evolution of HeII opacity,
the epoch of helium reionization, and the density of IGM baryons.

FGS 11212

Filling the Period Gap for Massive Binaries

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.

FGS 11211

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a
useful result, judged by the over ten refereed citations each year
since. It is, however, unsatisfactory to have the direct,
parallax-based, distance scale of Population II variables based on a
single star. We propose, therefore, to obtain the parallaxes of four
additional RR Lyrae stars and two Population II Cepheids, or W Vir
stars. The Population II Cepheids lie with the RR Lyrae stars on a
common K-band Period-Luminosity relation. Using these parallaxes to
inform that relationship, we anticipate a zero-point error of 0.04
magnitude. This result should greatly strengthen confidence in the
Population II distance scale and increase our understanding of RR
Lyrae star and Pop II Cepheid astrophysics.

NIC1/NIC2 11204

Imaging Circumstellar Disks and Envelopes around Proto-Brown Dwarfs

Using the Spitzer Space Telescope, we have discovered two young brown
dwarfs with Class I spectral energy distributions {i.e., proto-brown
dwarfs}. We propose to perform broad-band NICMOS imaging of these
Class I brown dwarfs to spatially resolve their circumstellar disks
and envelopes. If successful, these data would comprise the first
measurements of this kind for brown dwarfs and would provide
fundamental constraints on models for the formation of brown dwarfs.

WFPC2 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still
largely an open problem in cosmology: how does the Universe evolve
from large linear scales dominated by dark matter to the highly
non-linear scales of galaxies, where baryons and dark matter both play
important, interacting, roles? To understand the complex physical
processes involved in their formation scenario, and why they have the
tight scaling relations that we observe today {e.g. the Fundamental
Plane}, it is critically important not only to understand their
stellar structure, but also their dark-matter distribution from the
smallest to the largest scales. Over the last three years the SLACS
collaboration has developed a toolbox to tackle these issues in a
unique and encompassing way by combining new non-parametric strong
lensing techniques, stellar dynamics, and most recently weak
gravitational lensing, with high-quality Hubble Space Telescope
imaging and VLT/Keck spectroscopic data of early-type lens systems.
This allows us to break degeneracies that are inherent to each of
these techniques separately and probe the mass structure of early-type
galaxies from 0.1 to 100 effective radii. The large dynamic range to
which lensing is sensitive allows us both to probe the clumpy
substructure of these galaxies, as well as their low-density outer
haloes. These methods have convincingly been demonstrated, by our
team, using smaller pilot-samples of SLACS lens systems with HST data.
In this proposal, we request observing time with WFPC2 and NICMOS to
observe 53 strong lens systems from SLACS, to obtain complete
multi-color imaging for each system. This would bring the total number
of SLACS lens systems to 87 with completed HST imaging and effectively
doubles the known number of galaxy-scale strong lenses. The deep HST
images enable us to fully exploit our new techniques, beat down
low-number statistics, and probe the structure and evolution of
early-type galaxies, not only with a uniform data-set an order of
magnitude larger than what is available now, but also with a fully
coherent and self-consistent methodological approach!

ACS/SBC 11199

A Hard Look at Stellar Disks at the Epoch of Planet Formation

We propose to use HST/ACS/SBC and Chandra/ACIS-S3 to observe the high
energy fluxes of 4 stars surrounded by disks in the newly discovered
aggregate 25 Ori, the most populous 10 Myr group known within 500 pc.
Our observations will cover the 1-25A and 1250-2000A bandpasses, and
will complement our optical and Spitzer data for these objects, to
provide essential input to physically-consistent models of disk
structure and chemistry in the age range around 10 Myr, thought to be
a critical period in the planet- forming process. We will be able to
determine the Ne/O ratio and determine if the anomalous metal
abundances observed in X-ray spectra of young stars are an
evolutionary or an environmental effect. Our proposed observations
will double the number of 10 Myr old accreting stars with known high
energy radiation fields, and will be the first FUV observations of low
mass accreting stars in an OB association.

WEPC2 11196

An Ultraviolet Survey of Luminous Infrared Galaxies in the Local
Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
Luminous Infrared Galaxies {LIRGs} are primarily interacting or
merging disk galaxies undergoing starbursts and creating/fueling
central AGN. We propose far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W}
UV imaging of a sample of 27 galaxies drawn from the complete IRAS
Revised Bright Galaxy Sample {RBGS} LIRGs sample and known, from our
Cycle 14 B and I-band ACS imaging observations, to have significant
numbers of bright {23 B 21 mag} star clusters in the central 30
arcsec. The HST UV data will be combined with previously obtained HST,
Spitzer, and GALEX images to {i} calculate the ages of the clusters as
function of merger stage, {ii} measure the amount of UV light in
massive star clusters relative to diffuse regions of star formation,
{iii} assess the feasibility of using the UV slope to predict the far-
IR luminosity {and thus the star formation rate} both among and within
IR-luminous galaxies, and {iv} provide a much needed catalog of
rest-frame UV morphologies for comparison with rest-frame UV images of
high-z LIRGs and Lyman Break Galaxies. These observations will achieve
the resolution required to perform both detailed photometry of compact
structures and spatial correlations between UV and redder wavelengths
for a physical interpretation our IRX-Beta results. The HST UV data,
combined with the HST ACS, Spitzer, Chandra, and GALEX observations of
this sample, will result in the most comprehensive study of luminous
starburst galaxies to date.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of
Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens
a window into dynamical conditions in the protoplanetary disk where
they formed as well as the history of subsequent events which sculpted
the outer Solar System and emplaced them onto their present day
heliocentric orbits. To date, at least 47 TNBs have been discovered,
but only about a dozen have had their mutual orbits and separate
colors determined, frustrating their use to investigate numerous
important scientific questions. The current shortage of data
especially cripples scientific investigations requiring statistical
comparisons among the ensemble characteristics. We propose to obtain
sufficient astrometry and photometry of 23 TNBs to compute their
mutual orbits and system masses and to determine separate primary and
secondary colors, roughly tripling the sample for which this
information is known, as well as extending it to include systems of
two near-equal size bodies. To make the most efficient possible use of
HST, we will use a Monte Carlo technique to optimally schedule our
observations.

WFPC2 11170

UV Imaging of the Martian Corona and the Escape of Hydrogen

ACS SBC UV imaging observations of Mars are proposed to study the
extended hydrogen corona, with application to the escape of hydrogen
and the history of water on Mars. These observations will be scheduled
when Mars is distant from the Earth, so that a field of view of +/-
4-5 Mars radii can be obtained to image the full range of the highly
extended martian hydrogen corona through its H Ly alpha emission. The
observations will also be obtained when the Sun-Earth-Mars angle is
close to 90 degrees, so that any asymmetry along the Mars-Sun line can
be observed. The observed 2-dimensional brightness distribution will
be related to local density using two existing radiative transfer
codes, and the upward flux and velocity distributions will be
determined by comparison with runs from an exospheric distribution
model. These observations, combined with simultaneous Ly alpha
observations by the SPICAM instrument on Mars Express from within the
atmosphere, will provide the first tight constraints on the total
escape flux and importance of nonthermal processes on the rate of
escape.

WFPC2 11169

Collisions in the Kuiper belt

For most of the 15 year history of observations of Kuiper belt
objects, it has been speculated that impacts must have played a major
role in shaping the physical and chemical characteristics of these
objects, yet little direct evidence of the effects of such impacts has
been seen. The past 18 months, however, have seen an explosion of
major new discoveries giving some of the first insights into the
influence of this critical process. From a diversity of observations
we have been led to the hypotheses that: {1} satellite- forming
impacts must have been common in the Kuiper belt; {2} such impacts led
to significant chemical modification; and {3} the outcomes of these
impacts are sufficiently predictable that we can now find and study
these impact-derived systems by the chemical and physical attributes
of both the satellites and the primaries. If our picture is correct,
we now have in hand for the first time a set of incredibly powerful
tools to study the frequency and outcome of collisions in the outer
solar system. Here we propose three linked projects that would answer
questions critical to the multiple prongs of our hypothesis. In these
projects we will study the chemical effects of collisions through
spectrophotometric observations of collisionally formed satellites and
through the search for additional satellites around primaries with
potential impact signatures, and we will study the physical effects of
impacts through the examination of tidal evolution in proposed impact
systems. The intensive HST program that we propose here will allow us
to fully test our new hypotheses and will provide the ability to
obtain the first extensive insights into outer solar system impact
processes.

NIC2 11155

Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging
and Polarimetry

We propose to take advantage of the sensitive coronagraphic
capabilities of NICMOS to obtain multiwavelength coronagraphic imaging
and polarimetry of primordial dust disks around young
intermediate-mass stars {Herbig Ae stars}, in order to advance our
understanding of how dust grains are assembled into larger bodies.
Because the polarization of scattered light is strongly dependent on
scattering particle size and composition, coronagraphic imaging
polarimetry with NICMOS provides a uniquely powerful tool for
measuring grain properties in spatially resolved circumstellar disks.
It is widely believed that planets form via the gradual accretion of
planetesimals in gas-rich, dusty circumstellar disks, but the
connection between this suspected process and the circumstellar disks
that we can now observe around other stars remains very uncertain. Our
proposed observations, together with powerful 3-D radiative transfer
codes, will enable us to quantitatively determine dust grain
properties as a function of location within disks, and thus to test
whether dust grains around young stars are in fact growing in size
during the putative planet-formation epoch. HST imaging polarimetry of
Herbig Ae stars will complement and extend existing polarimetric
studies of disks around lower-mass T Tauri stars and debris disks
around older main-sequence stars. When combined with these previous
studies, the proposed research will help us establish the influence of
stellar mass on the growth of dust grains into larger planetesimals,
and ultimately to planets. Our results will also let us calibrate
models of the thermal emission from these disks, a critical need for
validating the properties of more distant disks inferred on the basis
of spectral information alone.

WFPC2 11146

The Role of Stellar Feedback in Galaxy Evolution

Stellar feedback - the return of mass and energy from star formation
to the interstellar medium - is one of the primary engines of galaxy
evolution. Yet, the observational canvass of feedback is incomplete.
We propose to investigate this fundamental aspect of star formation on
one local actively star-forming galaxy, He2-10, selected to occupy an
unexplored niche in the key parameter space of stellar mass. The WFPC2
narrow-band observations in the light of H-beta, [OIII], H-alpha, and
[SII] will: {1} discriminate the feedback-induced shock fronts from
the photoionized regions; {2} map, and provide a complete census of,
the shocks inside and around the starburst regions; and {3} measure
the energy budget of the star-formation-produced shocks. These
observations, joined by our previous data and studies on starbursts,
will yield: {1} the efficiency of the feedback, i.e. the fraction of
the star formation's mechanical energy transported out of the
starburst volume rather than radiated away, in the dual-parameter
space of host's stellar mass and star formation intensity; {2} the
conditions under which feedback morphs from a localized process to a
galactic scale mechanism. The high angular resolution of HST is
crucial for separating the spatially narrow shock fronts {~10 pc=0.2"
at 10 Mpc} from the more extended photoionization fronts. This project
will provide the most comprehensive quantitative foundation of stellar
feedback and a gauge for determining the role of feedback in the
energetics, structure and star formation history of galaxies.

ACS/SBC 11116

Exploring the Early FUV History of Cool Stars: Transition Regions at
30 Myr

Stellar magnetic activity derives from the so-called "dynamo," a
hydromagnetic interplay between overturning plasma motions and
differential rotation in stars cool enough to support significant
surface convection zones. The magnetic fields resulting from dynamo
action are in turn are responsible for a wide range of high-energy
emissions, including the spectacular outbursts called flares. Dynamo
powered magnetic activity is not confined solely to stars, but also
must occur, for example, in accretion disks of all descriptions, and
in some planets. A great deal is known about magnetic activity in
middle-aged G dwarfs like our Sun, thanks to its proximity. Less is
known, however, about the much younger stars, newly emerged from the
T-Tauri stage. Yet, it is during this phase that they reach the peak
of their magnetic activity, and subsidiary influences, such as the
impact of ionizing radiation and strong coronal winds on developing
solar systems, also are maximum. One of the key missing ingredients in
our current understanding are measurements of FUV emissions of such
stars, to complement the extensive collections of coronal {1-10 MK}
X-ray measurements, particularly from recent ROSAT, Chandra and
XMM-Newton surveys. We propose to conduct sensitive ACS/SBC prism
ultraviolet spectroscopy of selected fields in two young {30 Myr}
Galactic clusters--IC 2391 and IC 2602--to inventory the key C IV
emission index {~0.1 MK} over a much larger and more diverse sample of
coeval objects than has been possible hitherto. A key question is
whether the FUV emissions also suffer the "saturation" and
"super-saturation" at short rotation periods seen in coronal X-rays,
or whether they continue to rise in the fastest rotating stars. The
saturation behavior of the different temperature regimes holds
important clues to the organization of the surface active regions on
these very young stars, and should allow us to distinguish among
several competing models.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey
of a sample of 125 very X-ray luminous clusters in the redshift range
0.3-0.7. As demonstrated by the 25 snapshots obtained so far in
Cycle14 and Cycle15 these systems frequently exhibit strong
gravitational lensing as well as spectacular examples of violent
galaxy interactions. The proposed observations will provide important
constraints on the cluster mass distributions, the physical nature of
galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set
of optically bright, lensed galaxies for further 8-10m spectroscopy.
All of our primary science goals require only the detection and
characterization of high-surface-brightness features and are thus
achievable even at the reduced sensitivity of WFPC2. Because of their
high redshift and thus compact angular scale our target clusters are
less adversely affected by the smaller field of view of WFPC2 than
more nearby systems. Acknowledging the broad community interest in
this sample we waive our data rights for these observations. Due to a
clerical error at STScI our approved Cycle15 SNAP program was barred
from execution for 3 months and only 6 observations have been
performed to date - reinstating this SNAP at Cycle16 priority is of
paramount importance to reach meaningful statistics.

NIC3 11080

Exploring the Scaling Laws of Star Formation

As a variety of surveys of the local and distant Universe are
approaching a full census of galaxy populations, our attention needs
to turn towards understanding and quantifying the physical mechanisms
that trigger and regulate the large-scale star formation rates {SFRs}
in galaxies.

WFPC2 11070

WFPC2 CYCLE 15 Standard Darks - part II

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.

NIC1 11057

Cycle 15 NICMOS dark current, shading profile, and read noise
monitoring program

The purpose of this proposal is to monitor the dark current, read
noise, and shading profile for all three NICMOS detectors throughout
the duration of Cycle 15. This proposal is a slightly modified version
of proposal 10380 of cycle 13 and 9993 of cycle12 and is the same as
Cycle 14. that we cut down some exposure time to make the observation
fit within 24 orbits.

WFPC2 11037

Red Filters Closeout

This calibration program observes three very red stars {M, L, T
dwarfs} in the five reddest broad and medium filters {F785LP, F791W,
F814W, F850LP, and F1042M} on WF3 in order to allow cross-calibration
to ACS, and in future WFC3. The far-red QE curves will also be tested.
Similar observations on PC1 were made in WFPC2/CAL 10078 and 10366.

WFPC2 11024

WFPC2 CYCLE 15 INTERNAL MONITOR

This calibration proposal is the Cycle 15 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 th 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.

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.

WFPC2 10832

Solving the microlensing puzzle: An HST high-resolution imaging
approach

We propose to use the HST Advanced Camera for Surveys High Resolution
Channel to obtain high resolution imaging data for 10 bona-fide LMC
microlensing events seen in the original MACHO survey. The purpose of
this survey will be to assess whether or not the lens and source stars
have separated enough to be resolved since the original microlensing
event took place - about a decade has passed since the original MACHO
survey and the HST WFPC2 follow-up observations of the microlensing
events. If the components of the lensing event are resolved, we will
determine the apparent magnitude and color of both the lens and the
source stars. These data, in combination with Spitzer/IRAC data and
Magellan near-IR JHK data, will be used to ascertain the basic
properties of the lens stars. With the majority of the microlensing
events in the original MACHO survey observed at the highest spatial
resolution currently possible, we will be able to draw important
conclusions as to what fraction of these events have lenses which
belong to some population of dwarf stars in the disk and what fraction
must be due to lenses in the halo or beyond. These data will greatly
increase our understanding of the structure of the Galaxy by
characterizing the stellar population responsible for the
gravitational microlensing.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11052 - GSAcq (1,2,2) failed to RGA Hold during LOS

At acquisition of signal, 313/16:59:49, the GSAcq (1,2,2) scheduled
from 313/16:49:59 - 16:57:28 had failed to RGA Hold due to a stop flag
indication on FGS-1. No other 486 ESB messages were noted. Pre-acq
OBAD data is unavailable due to LOS. Post-acquisition OBAD MAP at
313/16:57:28 had an RSS value of 19.98 arcseconds

At acquisition of signal, 313/18:54:59, the REAcq (1,2,2) scheduled
from 313/18:22:15 - 18:29:44 had failed to RGA Hold due to a stop flag
indication on FGS-1. No other 486 ESB messages were noted. Pre-acq
OBAD data is unavailable due to LOS. Post-acquisition OBAD MAP at
313/16:57:28 had an RSS value of 13.12 arcseconds

11057 - REacq(1,2,2) failed to RGA Hold (Gyro Control)

REacq(1,2,2) scheduled at 316/02:30:31 - 02:38:36 failed to RGA Hold
due to a Search Radius Limit Exceeded Error on FGS-2. One 486 ESB
"a05" (FGS Coarse Track failed-Search Radius Limit Exceeded) was
received at 316/02:34:51. Pre-acquisition OBADs had (RSS) values of
709.42 and 47.8 arcseconds. Post-acq OBAD/MAP had (RSS) value of 42.32
arcseconds. Prior guide star acquisition was successful.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

************************* SCHEDULED***** SUCCESSFUL

FGS GSacq**************** 34***************** 33
FGS REacq**************** 25***************** 23
OBAD with Maneuver ***** 116**************** 116

SIGNIFICANT EVENTS:

Bi-Annual BCC Failover Test

The sixth biannual failover test to verify the backup control centers
ability to support critical real-time operations was successfully
executed on 11/9/07