Daily Report #5087

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5087

PERIOD COVERED: 5am April 30 - 5am May 03, 2010 (DOY 120/09:00z-123/09:00z)

OBSERVATIONS SCHEDULED

WFC3/UV/IR 12021

An Irradiated Disk in an Ultraluminous X-Ray Source

Whether ultraluminous X-ray sources (ULXs) contain stellar-mass or
intermediate-mass black holes (IMBHs) is an important, but as yet
unresolved, astrophysical question. We have discovered variable
optical emission from the ULX NGC 5408 X-1 that we interpret as
reprocessed emission in an irradiated disk. We propose simultaneous
observations with Chandra and HST to test this interpretation and
place constraints on the geometry of the accretion disk. The
observations should provide a means to discriminate between
stellar-mass versus intermediate-mass black holes.

ACS/WFC 11995

CCD Daily Monitor (Part 2)

This program comprises basic tests for measuring the read noise and
dark current of the ACS WFC and for tracking the growth of hot pixels.
The recorded frames are used to create bias and dark reference images
for science data reduction and calibration. This program will be
executed four days per week (Mon, Wed, Fri, Sun) for the duration of
Cycle 17. To facilitate scheduling, this program is split into three
proposals. This proposal covers 320 orbits (20 weeks) from 1 February
2010 to 20 June 2010.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more
reliably removed from science data using darks taken with the same
exposure sequences as the science data, than with a single dark
current image scaled by desired exposure time. Therefore, dark current
images must be collected using all sample sequences that will be used
in science observations. These observations will be used to monitor
changes in the dark current of the WFC3-IR channel on a day-to-day
basis, and to build calibration dark current ramps for each of the
sample sequences to be used by Gos in Cycle 17. For each sample
sequence/array size combination, a median ramp will be created and
delivered to the calibration database system (CDBS).

WFC3/UVIS/IR 11909

UVIS Hot Pixel Anneal

The on-orbit radiation environment of WFC3 will continually generate
new hot pixels. This proposal performs the procedure required for
repairing those hot pixels in the UVIS CCDs. During an anneal, the
two-stage thermo-electric cooler (TEC) is turned off and the
four-stage TEC is used as a heater to bring the UVIS CCDs up to ~20
deg. C. As a result of the CCD warmup, a majority of the hot pixels
will be fixed; previous instruments such as WFPC2 and ACS have seen
repair rates of about 80%. Internal UVIS exposures are taken before
and after each anneal, to allow an assessment of the procedure's
effectiveness in WFC3, provide a check of bias, global dark current,
and hot pixel levels, as well as support hysteresis (bowtie)
monitoring and CDBS reference file generation. One IR dark is taken
after each anneal, to provide a check of the IR detector.

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the
UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially found via an unexpected bowtie-shaped feature in flatfield
ratios, subsequent lab tests on similar e2v devices have since shown
that it is also present as simply an overall offset across the entire
CCD, i.e., a QE offset without any discernable pattern. These lab
tests have further revealed that overexposing the detector to count
levels several times full well fills the traps and effectively
neutralizes the bowtie. Each visit in this proposal acquires a set of
three 3x3 binned internal flatfields: the first unsaturated image will
be used to detect any bowtie, the second, highly exposed image will
neutralize the bowtie if it is present, and the final image will allow
for verification that the bowtie is gone.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set
of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K
subarray biases are acquired at less frequent intervals throughout the
cycle to support subarray science observations. The internals from
this proposal, along with those from the anneal procedure (Proposal
11909), will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

COS/FUV 11897

FUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity in each FUV
grating mode to detect any changes due to contamination or other
causes.

COS/NUV 11896

NUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity of each NUV
grating mode to detect any changes due to contamination or other
causes.

WFC3/ACS/UVIS 11877

HST Cycle 17 and Post-SM4 Optical Monitor

This program is the Cycle 17 implementation of the HST Optical
Monitoring Program.

The 36 orbits comprising this proposal will utilize ACS (Wide Field
Channel) and WFC3 (UVIS Channel) to observe stellar cluster members in
parallel with multiple exposures over an orbit. Phase retrieval
performed on the PSF in each image will be used to measure primarily
focus, with the ability to explore apparent coma, and astigmatism
changes in WFC3.

The goals of this program are to: 1) monitor the overall OTA focal
length for the purposes of maintaining focus within science tolerances
2) gain experience with the relative effectiveness of phase retrieval
on WFC3/UVIS PSFs 3) determine focus offset between the imagers and
identify any SI-specific focus behavior and dependencies

If need is determined, future visits will be modified to interleave
WFC3/IR channel and STIS/CCD focii measurements.

FGS 11875

Monitoring FGS2R2 Distortion and Alignment After SMOV4

This proposal monitors changes in the FGS2R2 distortion and alignment
after SMOV4 by observing selected stars in M35 in Position mode. Data
from each epoch are compared to track changes in FGS2R2. When the rate
of change becomes sufficiently slow, FGS2R2 will be cleared for a
mini-OFAD and FGS-FGS alignment calibration (carried out in another
phase 2 proposal).

STIS/CC 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,
and 1x1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

FGS 11789

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.

STIS/CCD/MA1 11737

The Distance Dependence of the Interstellar N/O Abundance Ratio: A
Gould Belt Influence?

The degree of elemental abundance homogeneity in the interstellar
medium is a function of the enrichment and mixing processes that
govern galactic chemical evolution. Observations of young stars and
the interstellar gas within ~500 pc of the Sun have revealed a local
ISM that is so well-mixed it is having an impact on ideas regarding
the formation of extrasolar planets. However, the situation just
beyond the local ISM is not so clear. Sensitive UV absorption line
measurements have recently revealed a pattern of inhomogeneities in
the interstellar O, N, and Kr gas-phase abundances at distances of
~500 pc and beyond that appear nucleosynthetic in origin rather than
due to dust depletion. In particular, based on a sample of 13
sightlines, Knauth et al. (2006) have found that the nearby stars (d
500 pc) exhibit a mean interstellar N/O abundance ratio that is
significantly higher (0.18 dex) than that toward the more distant
stars. Interestingly, all of their sightlines lie in the sky vicinity
of the Gould Belt of OB associations, molecular clouds, and diffuse
gas encircling the Sun at a distance of ~400 pc. Is it possible that
mixing processes have not yet smoothed out the recent ISM enrichment
by massive stars in the young Belt region? By measuring the
interstellar N/O ratios in a strategic new sample of sightlines with
STIS, we propose to test the apparent N/O homogeneity inside the Gould
Belt and determine if the apparent decline in the N/O ratio with
distance is robust and associated with the Belt region.

WFC3/UV/IR 11709

Stretching the Diversity of Cosmic Explosions: The Supernovae of
Gamma-ray Bursts

While the association between gamma-ray bursts (GRBs) and massive
stars is robust, there is a large diversity of properties among
supernovae (SNe) associated with GRBs. The converse is also true:
Several recent events show that there is a large brightness range
among high energy transients associated with SNe. As part of a
comprehensive program, we propose to use HST in order to search for
and characterize the SNe associated with GRB.

HST offers the means to cleanly separate the light curve of the GRB
afterglow from the supernova, and to remove the contamination from the
host galaxy, opening a clear path to the fundamental parameters of the
SN, and thence to the progenitor. From these observations, we will
determine the absolute magnitude at maximum, the shape of the spectral
energy distribution, and any change over time of the energy
distribution. We will also measure the rate of decay of the
exponential tail.

Merged with the ground-based data that we will obtain for each event,
we will be able to compare our data set to models and constrain the
energy of the explosion, the mass of the ejecta and the mass of Nickel
synthesized during the explosion. These results will shed light on the
apparent variety of supernovae associated with gamma-ray bursts and
X-ray flashes, and on the relation between these SNe and other, more
common, types of core-collapse explosions.

COS/FUV 11687

SNAPing Coronal Iron

This is a Snapshot Survey to explore two forbidden lines of highly
ionized iron in late-type coronal sources. Fe XII 1349 (T~ 2 MK) and
Fe XXI 1354 (T~ 10 MK) -- well known to Solar Physics -- have been
detected in about a dozen cool stars, mainly with HST/STIS. The UV
coronal forbidden lines are important because they can be observed
with velocity resolution of better than 15 km/s, whereas even the
state-of-the-art X-ray spectrometers on Chandra can manage only 300
km/s in the kilovolt band where lines of highly ionized iron more
commonly are found. The kinematic properties of hot coronal plasmas,
which are of great interest to theorists and modelers, thus only are
accessible in the UV at present. The bad news is that the UV coronal
forbidden lines are faint, and were captured only in very deep
observations with STIS. The good news is that 3rd-generation Cosmic
Origins Spectrograph, slated for installation in HST by SM4, in a mere
25 minute exposure with its G130M mode can duplicate the sensitivity
of a landmark 25-orbit STIS E140M observation of AD Leo, easily the
deepest such exposure of a late-type star so far. Our goal is to build
up understanding of the properties of Fe XII and Fe XXI in additional
objects beyond the current limited sample: how the lineshapes depend
on activity, whether large scale velocity shifts can be detected, and
whether the dynamical content of the lines can be inverted to map the
spatial morphology of the stellar corona (as in "Doppler Imaging'').
In other words, we want to bring to bear in the coronal venue all the
powerful tricks of spectroscopic remote sensing, well in advance of
the time that this will be possible exploiting the corona's native
X-ray radiation. The 1290-1430 band captured by side A of G130M also
contains a wide range of key plasma diagnostics that form at
temperatures from below 10, 000 K (neutral lines of CNO), to above
200, 000 K (semi-permitted O V 1371), including the important bright
multiplets of C II at 1335 and Si IV at 1400; yielding a diagnostic
gold mine for the subcoronal atmosphere. Because of the broad value of
the SNAP spectra, beyond the coronal iron project, we waive the normal
proprietary rights.

WFC3/UVIS 11675

Stellar Forensics: A Post-Explosion View of the Progenitors of
Core-Collapse Supernovae

Recent studies have used high spatial resolution HST observations of
SN sites to identify the progenitors of core-collapse SNe on
pre-explosion images. These studies have set constraints about the
nature of massive stars and their evolution just prior to their
explosion as SNe. Now, at late-times when the SNe have faded
sufficiently, it is possible to return to the sites of these
core-collapse SNe to search for clues about the nature of their
progenitors. We request time to conduct deep, late-time,
high-resolution imaging with ACS/HRC of the sites of six core-collapse
SNe. In this program we aim to: 1) confirm our identifications, that
were made with HST pre- explosion images, of the red supergiant
progenitors of four Type IIP SNe (1999ev, 2003gd, 2004A and 2005cs),
by observing if the objects identified as the progenitors are now
missing; 2) place precise constraints on the progenitor of the Type Ic
SN 2007gr by studying its host cluster; and 3) confirm our
identification of an LBV-like outburst of an unstable WR star as
belonging to the progenitor of a Type Ib-n core-collapse SN (2006jc),
using broad and narrow- band imaging to search for emission line stars
in its locality. The deep imaging will also allow to probe the stellar
populations in the immediate vicinities of these SNe, that were
previously obscured by the progenitors and the bright SNe. HST
provides the unique combination of high- resolution optical imaging at
very faint magnitudes that will facilitate this study.

WFC3/UV/IR 11664

The WFC3 Galactic Bulge Treasury Program: Populations, Formation
History, and Planets

Exploiting the full power of the Wide Field Camera 3 (WFC3), we
propose deep panchromatic imaging of four fields in the Galactic
bulge. These data will enable a sensitive dissection of its stellar
populations, using a new set of reddening-free photometric indices we
have constructed from broad-band filters across UV, optical, and
near-IR wavelengths. These indices will provide accurate temperatures
and metallicities for hundreds of thousands of individual bulge stars.
Proper motions of these stars derived from multi-epoch observations
will allow separation of pure bulge samples from foreground disk
contamination. Our catalogs of proper motions and panchromatic
photometry will support a wide range of bulge studies.

Using these photometric and astrometric tools, we will reconstruct the
detailed star-formation history as a function of position within the
bulge, and thus differentiate between rapid- and extended-formation
scenarios. We will also measure the dependence of the stellar mass
function on metallicity, revealing how the characteristic mass of star
formation varies with chemistry. Our sample of bulge stars with
accurate metallicities will include 12 candidate hosts of extrasolar
planets. Planet frequency is correlated with metallicity in the solar
neighborhood; our measurements will extend this knowledge to a remote
environment with a very distinct chemistry.

Our proposal also includes observations of six well-studied globular
and open star clusters; these observations will serve to calibrate our
photometric indices, provide empirical population templates, and
transform the theoretical isochrone libraries into the WFC3 filter
system. Besides enabling our own program, these products will provide
powerful new tools for a host of other stellar-population
investigations with HST/WFC3. We will deliver all of the products from
this Treasury Program to the community in a timely fashion.

WFC3/UV/ACS/WFC 11636

First Resolved Imaging of Escaping Lyman Continuum

The emission from star-forming galaxies appears to be responsible for
reionization of the universe at z 6. However, the models that
attempt to describe the detailed impact of high-redshift galaxies on
the surrounding inter-galactic medium (IGM) are strongly dependent
upon several uncertain parameters. Perhaps the most uncertain is the
fraction of HI-ionizing photons produced by young stars that escape
into the IGM. Most attempts to measure this "escape fraction" have
produced null results. Recently, a small subset of z~3 Lyman Break
Galaxies (LBGs) has been found exhibiting large escape fractions. It
remains unclear however, what differentiates them from other LBGs.
Several models attempt to explain how such a large fraction of
ionizing continuum can escape through the HI and dust in the ISM (eg.
"chimneys" created by SNe winds, globular cluster formation, etc.),
each producing unique signatures which can be observed with resolved
imaging of the escaping Lyman continuum. To date, there are only six
LBGs with individual detections of escaping Lyman continuum at any
redshift. We propose a single deep, high resolution WFC3/UVIS image of
the ionizing continuum (F336W) and the rest-frame UV/optical
(F606W/F814W/F160W) of five of these six LBGs with large escape
fractions. These LBGs have a high surface density and large escape
fractions, and lie at the optimal redshift for Lyman continuum imaging
with UVIS filters, making our sample especially suitable for
follow-up. With these data we will discern the mechanisms responsible
for producing large escape fractions, and therefore gain insight into
the process of reionization.

WFC3/UVIS 11628

Globular Cluster Candidates for Hosting a Central Black Hole

We are continuing our study of the dynamical properties of globular
clusters and we propose to obtain surface brightness profiles for high
concentration clusters. Our results to date show that the distribution
of central surface brightness slopes do not conform to standard
models. This has important implications for how they form and evolve,
and suggest the possible presence of central intermediate-mass black
holes. From our previous archival proposals (AR-9542 and AR- 10315),
we find that many high concentration globular clusters do not have
flat cores or steep central cusps, instead they show weak cusps.
Numerical simulations suggest that clusters with weak cusps may harbor
intermediate-mass black holes and we have one confirmation of this
connection with omega Centauri. This cluster shows a shallow cusp in
its surface brightness profile, while kinematical measurements suggest
the presence of a black hole in its center. Our goal is to extend
these studies to a sample containing 85% of the Galactic globular
clusters with concentrations higher than 1.7 and look for objects
departing from isothermal behavior. The ACS globular cluster survey
(GO-10775) provides enough objects to have an excellent coverage of a
wide range of galactic clusters, but it contains only a couple of the
ones with high concentration. The proposed sample consists of clusters
whose light profile can only be adequately measured from space-based
imaging. This would take us close to completeness for the high
concentration cases and therefore provide a more complete list of
candidates for containing a central black hole. The dataset will also
be combined with our existing kinematic measurements and enhanced with
future kinematic studies to perform detailed dynamical modeling.

STIS/CCD 11606

Dynamical Hypermassive Black Hole Masses

We will use STIS spectra to derive the masses of 5 hypermassive black
holes (HMBHs). From the observed scaling relations defined by less
massive spheroids, these objects are expected to reside at the nuclei
of host galaxies with stellar velocity dispersions greater than 320
km/s. These 5 targets have confirmed regular gas distributions on the
scales of the black hole sphere of influence. It is essential that the
sphere of influence is resolved for accurate determinations of black
hole mass (0.1"). These scales cannot be effectively observed from the
ground. Only two HMBHs have had their masses modeled so far; it is
impossible to draw any general conclusions about the connections
between HMBH mass and their massive host galaxies. With these 5
targets we will determine whether these HMBHs deviate from the scaling
relations defined by less massive spheroids. A larger sample will
allow us to firmly anchor the high mass end of the correlation between
black hole mass and stellar velocity dispersion, and other scaling
relations. Therefore we are also conducting a SNAPshot program with
which we expect to detect a further 24 HMBH candidates for STIS
observation in future cycles. At the completion of this project we
will have populated the high mass end of the scaling relations with
the sample sizes enjoyed by less massive spheroids.

ACS/WFC3 11604

The Nuclear Structure of OH Megamaser Galaxies

We propose a snapshot survey of a complete sample of 80 OH megamaser
galaxies. Each galaxy will be imaged with the ACS/WFC through F814W
and a linear ramp filter (FR656N or FR716N or FR782N or FR853N)
allowing us to study both the spheroid and the gas morphology in
Halpha + [N II]. We will use the 9% ramps FR647M (5370-7570 angstroms)
centered at 7000 angstroms and FR914M (7570-10, 719 angstroms) 8000
angstroms for continuum subtraction for the high and low z objects
respectively. OH megamaser galaxies (OHMG) form an important class of
ultraluminous IR-galaxies (ULIRGs) whose maser lines emit QSO-like
luminosities. ULIRGs in general are associated with recent mergers but
it is often unclear whether their power output is dominated by
starbursts or a hidden QSO because of the high absorbing columns which
hide their nuclei even at X-ray wavelengths. In contrast, OHMG exhibit
strong evidence for the presence of an energetically important and
recently triggered active nucleus. In particular it is clear that much
of the gas must have already collapsed to form a nuclear disk which
may be the progenitor of a circum-nuclear torus, a key element of the
unified scheme of AGN. A great advantage of studying OHMG systems over
the general ULIRG population, is that the circum-nuclear disks are
effectively "fixed" at an inner, edge on, orientation, eliminating
varying inclination as a nuisance parameter. We will use the HST
observations in conjunction with existing maser and spectroscopic data
to construct a detailed picture of the circum-nuclear regions of a
hitherto relatively neglected class of galaxy that may hold the key to
understanding the relationship between galaxy mergers, nuclear
star-formation, and the growth of massive black holes and the
triggering of nuclear activity.

ACS/WFC3 11599

Distances of Planetary Nebulae from SNAPshots of Resolved Companions

Reliable distances to individual planetary nebulae (PNe) in the Milky
Way are needed to advance our understanding of their spatial
distribution, birthrates, influence on galactic chemistry, and the
luminosities and evolutionary states of their central stars (CSPN).
Few PNe have good distances, however. One of the best ways to remedy
this problem is to find resolved physical companions to the CSPN and
measure their distances by photometric main-sequence fitting. We have
previously used HST to identify and measure probable companions to 10
CSPN, based on angular separations and statistical arguments only. We
now propose to use HST to re-observe 48 PNe from that program for
which additional companions are possibly present. We then can use the
added criterion of common proper motion to confirm our original
candidate companions and identify new ones in cases that could not
confidently be studied before. We will image the region around each
CSPN in the V and I bands, and in some cases in the B band. Field
stars that appear close to the CSPN by chance will be revealed by
their relative proper motion during the 13+ years since our original
survey, leaving only genuine physical companions in our improved and
enlarged sample. This study will increase the number of Galactic PNe
with reliable distances by 50 percent and improve the distances to PNe
with previously known companions.

WFC3/UVIS 11594

A WFC3 Grism Survey for Lyman Limit Absorption at z=2

We propose to conduct a spectroscopic survey of Lyman limit absorbers
at redshifts 1.8 z 2.5, using WFC3 and the G280 grism. This
proposal intends to complete an approved Cycle 15 SNAP program
(10878), which was cut short due to the ACS failure. We have selected
64 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 16.0 log(NHI) 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 16.0 log(NHI) 17.5 cm^-2. Third, we will
identify those sightlines which could provide a measurement of the
primordial D/H ratio. By carrying out this survey, we can also help
place meaningful constraints on two key quantities of cosmological
relevance. First, we will estimate the amount of metals in the LLS
using the f(N), and ground based observations of metal line
transitions. Second, by determining f(N) of the PLLS, we can constrain
the amplitude of the ionizing UV background at z~2 to a greater
precision. This survey is ideal for a snapshot observing program,
because the on-object integration times are all well below 30 minutes,
and follow-up observations from the ground require minimal telescope
time due to the QSO sample being bright.

ACS/WFC/WFC3/UV 11578

The Extremely Metal-Poor BCD Galaxy DDO 68: a Young Galaxy in the
Local Universe ?

A long standing question in astrophysics is the existence of young
galaxies, in which stars are now forming for the first time, in the
nearby (i.e., present-day) universe. Such galaxies would be the local
analogs of primordial galaxies observed at high redshift. The most
promising candidates have long been the most metal-poor systems,
including dwarf irregulars (dIrrs) and blue compact dwarfs (BCDs).
However, in many dIrrs and BCDs studied with HST an old (1 Gyr)
underlying stellar population, as traced by red giant branch (RGB)
stars, has been unambiguously detected. Even in I Zw 18, which is the
most-metal poor prototype of the class and long the most controversial
case, our group has recently succeeded in detecting an RGB.
Nonetheless, there remains the possibility that the star formation
histories of BCDs/dIrrs vary from galaxy to galaxy, and that truly
young galaxies do exist in the local universe. A new test of these
issues has only recently become possible with the identification of
DDO 68 as an extremely metal-poor galaxy with an oxygen abundance
equal to that of I Zw 18 (12+(O/H)=7.21). This galaxy is about a
factor of 2-3 closer than I Zw 18, which yields the opportunity to
avoid the many ambiguities that have plagued studies of I Zw 18. Also,
DDO 68 resides in a void, making it more likely that star formation
has been suppressed for a very long time. We will observe DDO 68 with
ACS/WFC in F606W and F814W, plus F658N (Halpha) to correct the broad
F606W for gas contamination. We will use WFC3 in parallel with the
same filters to study radial population gradients. Deep
color-magnitude diagrams (CMDs) reaching the depth of one magnitude
below the predicted RGB tip will be constructed and interpreted based
on synthetic CMD fitting. These data will determine unambiguously
whether DDO 68 has an underlying old (RGB) stellar population or is
forming stars for the first time. Finding just a single nearby
``young'' galaxy would have profound cosmological implications.

STIS/CCD 11567

Boron Abundances in Rapidly Rotating Early-B Stars

Models of rotation in early-B stars predict that rotationally driven
mixing should deplete surface boron abundances during the
main-sequence lifetime of many stars. However, recent work has shown
that many boron depleted stars are intrinsically slow rotators for
which models predict no depletion should have occurred, while
observations of nitrogen in some more rapidly rotating stars show less
mixing than the models predict. Boron can provide unique information
on the earliest stages of mixing in B stars, but previous surveys have
been biased towards narrow- lined stars because of the difficulty in
measuring boron abundances in rapidly rotating stars. The two targets
observed as part of our Cycle 13 SNAP program 10175, just before STIS
failed, demonstrate that it is possible to make useful boron abundance
measurements for early-B stars with Vsin(i) above 100 km/s. We propose
to extend that survey to a large enough sample of stars to allow
statistically significant tests of models of rotational mixing in
early-B stars.

NIC2/WFC3/IR 11548

Infrared Imaging of Protostars in the Orion A Cloud: The Role of
Environment in Star Formation

We propose NICMOS and WFC3/IR observations of a sample of 252
protostars identified in the Orion A cloud with the Spitzer Space
Telescope. These observations will image the scattered light escaping
the protostellar envelopes, providing information on the shapes of
outflow cavities, the inclinations of the protostars, and the overall
morphologies of the envelopes. In addition, we ask for Spitzer time to
obtain 55-95 micron spectra of 75 of the protostars. Combining these
new data with existing 3.6 to 70 micron photometry and forthcoming
5-40 micron spectra measured with the Spitzer Space Telescope, we will
determine the physical properties of the protostars such as envelope
density, luminosity, infall rate, and outflow cavity opening angle. By
examining how these properties vary with stellar density (i.e.
clusters vs. groups vs. isolation) and the properties of the
surrounding molecular cloud; we can directly measure how the
surrounding environment influences protostellar evolution, and
consequently, the formation of stars and planetary systems.
Ultimately, this data will guide the development of a theory of
protostellar evolution.

NIC3/WFC3/IR 11149

Characterizing the Stellar Populations in Lyman-Alpha Emitters and
Lyman Break Galaxies at 5.7z7 in the Subaru Deep Field

The epoch of reionization marks a major phase transition of the
Universe, during which the intergalactic space became transparent to
UV photons. Determining when this occurred and the physical processes
involved represents the latest frontier in observational cosmology.
Over the last few years, searches have intensified to identify the
population of high-redshift (z6) galaxies that might be responsible
for this process, but the progress is hampered partly by the
difficulty of obtaining physical information (stellar mass, age, star
formation rate/history) for individual sources. This is because the
number of z6 galaxies that have both secure spectroscopic redshifts
and high-quality infrared photometry (especially with Spitzer/IRAC) is
still fairly small. Considering that only several photometric points
are available per source, and that many model SEDs are highly
degenerate, it is crucial to obtain as many observational constraints
as possible for each source to ensure the validity of SED modeling. To
better understand the physical properties of high-redshift galaxies,
we propose here to conduct HST/NICMOS (72 orbits) and Spitzer/IRAC
(102 hours) imaging of spectroscopically confirmed, bright (z26 mag
(AB)) Ly-alpha emitters (LAEs) and Lyman-break galaxies (LBGs) at
5.7z7 selected from the Subaru Deep Field. Spectroscopic redshifts
remove one critical free parameter from SED modeling while bright
source magnitudes ensure high-quality photometric data. By making
accurate determinations of stellar masses, ages, and star-formation
histories, we will specifically address the following major questions:
(1) Do LAEs and LBGs represent physically different galaxy populations
at z6 as suggested recently? (2) Is Ly-alpha emission systematically
suppressed at z6 with respect to continuum emission? (i.e., are we
reaching the epoch of incomplete reionization?), and (3) Do we see any
sign of abnormally young stellar population in any of the z6
galaxies?

WFC3/ACS/IR 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at
0.3z2.7 Using HST and Spitzer

We aim to determine physical properties of IR luminous galaxies at
0.3z2.7 by requesting coordinated HST/NIC2 and MIPS 70um
observations of a unique, 24um flux-limited sample with complete
Spitzer mid-IR spectroscopy. The 150 sources investigated in this
program have S(24um) 0.8mJy and their mid-IR spectra have already
provided the majority targets with spectroscopic redshifts
(0.3z2.7). The proposed 150~orbits of NIC2 and 66~hours of MIPS 70um
will provide the physical measurements of the light distribution at
the rest-frame ~8000A and better estimates of the bolometric
luminosity. Combining these parameters together with the rich suite of
spectral diagnostics from the mid-IR spectra, we will (1) measure how
common mergers are among LIRGs and ULIRGs at 0.3z2.7, and establish
if major mergers are the drivers of z1 ULIRGs, as in the local
Universe, (2) study the co-evolution of star formation and blackhole
accretion by investigating the relations between the fraction of
starburst/AGN measured from mid-IR spectra vs. HST morphologies,
L(bol) and z, and (3) obtain the current best estimates of the far-IR
emission, thus L(bol) for this sample, and establish if the relative
contribution of mid-to-far IR dust emission is correlated with
morphology (resolved vs. unresolved).

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 25 25
FGS REAcq 22 22
OBAD with Maneuver 22 22

SIGNIFICANT EVENTS: (None)