Daily Report #5072

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5072

PERIOD COVERED: 5am April 9 - 5am April 12, 2010 (DOY 099/09:00z-102/09:00z)

OBSERVATIONS SCHEDULED

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 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).

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the
MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each
detector. However, starting Oct 5, pairs are only included for weeks
that the LRP has external MAMA observations planned. The weekly pairs
of exposures for each detector are linked so that they are taken at
opposite ends of the same SAA free interval. This pairing of exposures
will make it easier to separate long and short term temporal
variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once
every six months. These are groups of five 1314s FUV-MAMA Time-Tag
darks or five 3x315s NUV ACCUM darks distributed over a single
SAA-free interval. This will give more information on the brightness
of the FUV MAMA dark current as a function of the amount of time that
the HV has been on, and for the NUV MAMA will give a better measure of
the short term temperature dependence.

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.

COS/NUV/FUV 11728

The Impact of Starbursts on the Gaseous Halos of Galaxies

Perhaps the most important (yet uncertain) aspects of galaxy evolution
are the processes by which galaxies accrete gas and by which the
resulting star formation and black hole growth affects this accreting
gas. It is believed that both the form of the accretion and the nature
of the feedback change as a function of the galaxy mass. At low mass
the gas comes in cold and the feedback is provided by massive stars.
At high mass, the gas comes in hot, and the feedback is from an AGN.
The changeover occurs near the mass where the galaxy population
transitions from star-forming galaxies to red and dead ones. The
population of red and dead galaxies is building with cosmic time, and
it is believed that feedback plays an important role in this process:
shutting down star formation by heating and/or expelling the reservoir
of cold halo gas. To investigate these ideas, we propose to use COS
far-UV spectra of background QSOs to measure the properties of the
halo gas in a sample of galaxies near the transition mass that have
undergone starbursts within the past 100 Myr to 1 Gyr. The galactic
wind associated with the starburst is predicted to have affected the
properties of the gaseous halo. To test this, we will compare the
properties of the halos of the post-starburst galaxies to those of a
control sample of galaxies matched in mass and QSO impact parameter.
Do the halos of the post-starburst galaxies show a higher incidence
rate of Ly-Alpha and metal absorption-lines? Are the kinematics of the
halo gas more disturbed in the post-starbursts? Has the wind affected
the ionization state and/or the metallicity of the halo? These data
will provide fresh new insights into the role of feedback from massive
stars on the evolution of galaxies, and may also offer clues about the
properties of the QSO metal absorption-line systems at high-redshift .

ACS/WFC 11715

The Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its
Nested Light Echoes

RS Puppis is one of the most luminous Cepheids in the Milky Way (P =
41.4 days) and an analog of the bright Cepheids used to measure
extragalactic distances. An accurate distance would help anchor the
zero-point of the bright end of the period-luminosity relation, but at
a distance of about 2 kpc it is too far away for a trigonometric
parallax with existing instrumentation.

RS Pup is unique in being surrounded by a reflection nebula, whose
brightness varies as pulses of light from the Cepheid propagate
outwards. Members of our team have used ground-based imaging of the
nebula to derive phase lags in the light variations of individual
features in the nebula, and have inferred a seemingly very precise
geometric distance to the star. However, there is an unavoidable
ambiguity involving the cycle counts, which was resolved by assuming
that the features lie in the plane of the sky. If this assumption is
incorrect, a large systematic error would be introduced into the
distance measurement.

We show that polarimetric imaging using the high spatial resolution of
ACS/WFC and its ability to image close to the star can resolve this
ambiguity and yield a reliable geometric distance to RS Pup. We will
also obtain a wide-field multicolor image of the nebula, in order to
study its morphology and the mass-loss history of the Cepheid.

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.

STIS/CCD 11703

The Nature of the Black Hole in a NGC 4472 Globular Cluster and the
Origin of Its Broad [OIII] Emission

We propose to use STIS to obtain optical spectroscopy at high spatial
resolution of the black hole-hosting globular cluster RZ2109 in the
Virgo elliptical NGC 4472. This is motivated by our very recent
discovery broad [OIII] 4959, 5007 emission with a width of several
thousand km/s in this globular cluster. The STIS spectroscopy will
enable us to determine if the very broad [OIII] emission is due to
material driven at high velocity from the central accreting black hole
across the globular cluster, or if the velocity widths are due to
gravitational motions very close to the central black hole. In the
former case, the [OIII] emission should extend over a few-tenths of an
arcsecond and be spatially resolved by HST and STIS, while in the
latter case, the emission lines will be unresolved. Distinguishing
between these two possibilities will allow us to - 1) determine
whether the black hole is of intermediate mass or a stellar mass, and
thereby whether the black hole mass - sigma relation extends to
globular cluster masses, 2) test models of black hole formation and
evolution in dense stellar systems, and 3) address the nature of
accretion in the high luminosity black-hole X-ray source, and
constrain the feedback processes from luminous black holes into their
surrounding medium in dense stellar systems.

COS/FUV 11699

On the Evolutionary Status of Extremely Hot Helium Stars - are the
O(He) Stars Successors of the R CrB Stars?

We propose UV spectroscopy of the four unique post-AGB stars of
spectral type O(He) in order to understand the origin of their
peculiar surface abundances. These stars are the only known amongst
the hottest post-AGB stars (effective temperatures 100, 000 K) whose
atmospheres are composed of almost pure helium. This chemistry
markedly differs from that of the hydrogen-deficient post-AGB
evolutionary sequence with objects which have carbon dominated
atmospheres (PG1159 stars and Wolf-Rayet central stars).

While PG1159 and Wolf-Rayet stars are the result of a late
helium-shell flash, this scenario cannot explain the O(He) stars.
Instead, they are possibly double-degenerate mergers. We speculate
that the four O(He) stars represent evolved RCrB stars, which also
have helium-dominated atmospheres. We aim to determine the C, N, O,
and Si abundances precisely, in order to proof this evolutionary link.

WFC3/IR 11696

Infrared Survey of Star Formation Across Cosmic Time

We propose to use the unique power of WFC3 slitless spectroscopy to
measure the evolution of cosmic star formation from the end of the
reionization epoch at z6 to the close of the galaxy- building era at
z~0.3.Pure parallel observations with the grisms have proven to be
efficient for identifying line emission from galaxies across a broad
range of redshifts. The G102 grism on WFC3 was designed to extend this
capability to search for Ly-alpha emission from the first galaxies.
Using up to 250 orbits of pure parallel WFC3 spectroscopy, we will
observe about 40 deep (4-5 orbit) fields with the combination of G102
and G141, and about 20 shallow (2-3 orbit) fields with G141 alone.

Our primary science goals at the highest redshifts a (1) Detect Lya
in ~100 galaxies with z5.6 and measure the evolution of the Lya
luminosity function, independent of of cosmic variance; 2) Determine
the connection between emission line selected and continuum-break
selected galaxies at these high redshifts, and 3) Search for the
proposed signature of neutral hydrogen absorption at re-ionization. At
intermediate redshifts we will (4) Detect more than 1000 galaxies in
Halpha at 0.5z1.8 to measure the evolution of the
extinction-corrected star formation density across the peak epoch of
star formation. This is over an order-of-magnitude improvement in the
current statistics, from the NICMOS Parallel grism survey. (5) Trace
``cosmic downsizing" from 0.5z2.2; and (6) Estimate the evolution in
reddening and metallicty in star- forming galaxies and measure the
evolution of the Seyfert population. For hundreds of spectra we will
be able to measure one or even two line pair ratios -- in particular,
the Balmer decrement and [OII]/[OIII] are sensitive to gas reddening
and metallicity. As a bonus, the G102 grism offers the possibility of
detecting Lya emission at z=7-8.8.

To identify single-line Lya emitters, we will exploit the wide
0.8--1.9um wavelength coverage of the combined G102+G141 spectra. All
[OII] and [OIII] interlopers detected in G102 will be reliably
separated from true LAEs by the detection of at least one strong line
in the G141 spectrum, without the need for any ancillary data. We
waive all proprietary rights to our data and will make high-level data
products available through the ST/ECF.

COS/FUV 11686

The Cosmological Impact of AGN Outflows: Measuring Absolute Abundances
and Kinetic Luminosities

AGN outflows are increasingly invoked as a major contributor to the
formation and evolution of supermassive black holes, their host
galaxies, the surrounding IGM, and cluster cooling flows. Our HST/COS
proposal will determine reliable absolute chemical abundances in six
AGN outflows, which influences several of the processes mentioned
above. To date there is only one such determination, done by our team
on Mrk 279 using 16 HST/STIS orbits and 100 ksec of FUSE time. The
advent of COS and its high sensitivity allows us to choose among
fainter objects at redshifts high enough to preclude the need for
FUSE. This will allow us to determine the absolute abundances for six
AGN (all fainter than Mrk 279) using only 40 HST COS orbits. This will
put abundances studies in AGN on a firm footing, an elusive goal for
the past four decades. In addition, prior FUSE observations of four of
these targets indicate that it is probable that the COS observations
will detect troughs from excited levels of C III. These will allow us
to measure the distances of the outflows and thereby determine their
kinetic luminosity, a major goal in AGN feedback research.
11686( 7) - 25-Sep-2009 13:44:14 - [ 2]

We will use our state of the art column density extraction methods and
velocity-dependent photoionization models to determine the abundances
and kinetic luminosity. Previous AGN outflow projects suffered from
the constraints of deciding what science we could do using ONE of the
handful of bright targets that were observable. With COS we can choose
the best sample for our experiment. As an added bonus, most of the
spectral range of our targets has not been observed previously,
greatly increasing the discovery phase space.

WFC3/ACS/IR 11677

Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing
a Hubble Legacy

With this proposal we will firmly establish the age of 47 Tuc from its
cooling white dwarfs. 47 Tuc is the nearest and least reddened of the
metal-rich disk globular clusters. It is also the template used for
studying the giant branches of nearby resolved galaxies. In addition,
the age sensitive magnitude spread between the main sequence turnoff
and horizontal branch is identical for 47 Tuc, two bulge globular
clusters and the bulge field population. A precise relative age
constraint for 47 Tuc, compared to the halo clusters M4 and NGC 6397,
both of which we recently dated via white dwarf cooling, would
therefore constrain when the bulge formed relative to the old halo
globular clusters. Of particular interest is that with the higher
quality ACS data on NGC 6397, we are now capable with the technique of
white dwarf cooling of determining ages to an accuracy of +/-0.4 Gyrs
at the 95% confidence level. Ages derived from the cluster turnoff are
not currently capable of reaching this precision. The important role
that 47 Tuc plays in galaxy formation studies, and as the metal-rich
template for the globular clusters, makes the case for a white dwarf
cooling age for this metal-rich cluster compelling.

Several recent analyses have suggested that 47 Tuc is more than 2 Gyrs
younger than the Galactic halo. Others have suggested an age similar
to that of the most metal poor globular clusters. The current
situation is clearly uncertain and obviously a new approach to age
dating this important cluster is required.

With the observations of 47 Tuc, this project will complete a legacy
for HST. It will be the third globular cluster observed for white
dwarf cooling; the three covering almost the full metallicity range of
the cluster system. Unless JWST has its proposed bluer filters (700
and 900 nm) this science will not be possible perhaps for decades
until a large optical telescope is again in space. Ages for globular
clusters from the main sequence turnoff are less precise than those
from white dwarf cooling making the science with the current proposal
truly urgent.

WFC3/UVIS/IR 11662

Improving the Radius-Luminosity Relationship for Broad-Lined AGNs with
a New Reverberation Sample

The radius-luminosity (R-L) relationship is currently the fundamental
basis for all techniques used to estimate black hole masses in AGNs,
in both the nearby and distant universe. However, the current R-L
relationship is based on 34 objects that cover a limited range in
black hole mass and luminosity. To improve our understanding of black
hole growth and evolution, the R-L relationship must be extended to
cover a broader range of black hole masses using the technique known
as reverberation mapping. To this end, we have been awarded an
unprecedented 64 nights on the Lick Observatory 3-m telescope between
March 24 and May 31, 2008, to spectroscopically monitor 12 AGNs in
order to measure their black hole masses. To properly determine the
luminosities of these 12 AGNs, we must correct them for their
host-galaxy starlight contributions using high-resolution images.
Previous work by Bentz et al. (2006) has shown that the starlight
correction to AGN luminosity measurements is an essential component to
interpreting the R-L relationship. The correction will be substantial
for each of the 12 sources we will monitor, as the AGNs are relatively
faint and embedded in nearby, bright galaxies. Starlight corrections
are not possible with ground-based images, as the PSF and bulge
contributions become indistinguishable under typical seeing
conditions, and adaptive optics are not yet operational in the
spectral range where the corrections are needed. In addition, spectral
decompositions are very model-dependent and are limited by the degree
of accuracy to which we understand emission processes and stellar
populations in galaxies. Without correcting for starlight, we will be
unable to apply the results of our Spring 2008 campaign to the body of
knowledge from previous reverberation mapping work. Therefore, we
propose to obtain high resolution, high dynamic range images of the
host galaxies of the 12 AGNs in our ground-based monitoring sample, as
well as one white dwarf which will be used as a PSF model.

WFC3/UVIS/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into
the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass,
but their small numbers, coupled with their stochastic pasts, make it
impossible to construct a unique formation history from the dynamical
or compositional characteristics of them alone. In contrast, the huge
numbers of small bodies scattered throughout and even beyond the
planets, while insignificant by mass, provide an almost unlimited
number of probes of the statistical conditions, history, and
interactions in the solar system. To date, attempts to understand the
formation and evolution of the Kuiper Belt have largely been dynamical
simulations where a hypothesized starting condition is evolved under
the gravitational influence of the early giant planets and an attempt
is made to reproduce the current observed populations. With little
compositional information known for the real Kuiper Belt, the test
particles in the simulation are free to have any formation location
and history as long as they end at the correct point. Allowing
compositional information to guide and constrain the formation,
thermal, and collisional histories of these objects would add an
entire new dimension to our understanding of the evolution of the
outer solar system. While ground based compositional studies have hit
their flux limits already with only a few objects sampled, we propose
to exploit the new capabilities of WFC3 to perform the first ever
large-scale dynamical-compositional study of Kuiper Belt Objects
(KBOs) and their progeny to study the chemical, dynamical, and
collisional history of the region of the giant planets. The
sensitivity of the WFC3 observations will allow us to go up to two
magnitudes deeper than our ground based studies, allowing us the
capability of optimally selecting a target list for a large survey
rather than simply taking the few objects that can be measured, as we
have had to do to date. We have carefully constructed a sample of 120
objects which provides both overall breadth, for a general
understanding of these objects, plus a large enough number of objects
in the individual dynamical subclass to allow detailed comparison
between and within these groups. These objects will likely define the
core Kuiper Belt compositional sample for years to come. While we have
many specific results anticipated to come from this survey, as with
any project where the field is rich, our current knowledge level is
low, and a new instrument suddenly appears which can exploit vastly
larger segments of the population, the potential for discovery -- both
anticipated and not -- is extraordinary.

WFC3/UV 11635

In Search of SNIb/Ic Wolf-Rayet Progenitors and Comparison with Red
Supergiants (SNII Progenitors) in the Giant ScI Spiral M101

We propose to test two of the clearest predictions of the theory of
evolution of massive-star evolution: 1) The formation of Wolf-Rayet
stars depends strongly on these stars' metallicity (Z), with
relatively fewer WR stars forming at lower Z, and 2) Wolf-Rayet stars
die as Type Ib or Ic supernovae. To carry out these tests we propose a
deep, narrowband imaging survey of the massive star populations in the
ScI spiral galaxy M101. Just as important, we will test the hypothesis
that Superclusters like 30 Doradus are always richly populated with WR
stars, and by implication that these complexes are responsible for the
spectral signatures of starburst galaxies.

Our previous HST survey of the HII regions in the ScIII galaxy NGC
2403 suggested that the distribution of WR stars and RSG is a
sensitive diagnostic of the recent star-forming history of these large
complexes: young cores of O and WR stars are surrounded by older halos
containing RSG. Theory predicts that this must change with
metallicity; relatively fewer WR stars form at lower Z. A key goal of
our proposal is to directly test this paradigm in a single galaxy,
M101 being the ideal target. The abundance gradient across M101 (a
factor of 20) suggests that relatively many more WR will be found in
the inner parts of this galaxy than in the outer "suburbs". Second, we
note that WR stars are predicted to end their lives as core-collapse
or pair-instability supernovae. The WR population in M101 may be
abundant enough for one to erupt as a Type Ib or Ic supernova within a
generation. The clear a priori identification of a WR progenitor would
be a major legacy of HST. Third, we will also determine if
"superclusters", heavily populated by WR stars, are common in M101. It
is widely claimed that such Superclusters produce the integrated
spectral signatures of Starburst galaxies. We will be able to directly
measure the numbers and emission-line luminosities of thousands of
Wolf Rayet stars located in hundreds of M101 Superclusters, and
correlate those numbers against the Supercluster sizes and
luminosities. It is likely (but far from certain) that Supercluster
sizes and emission-line luminosities are driven by their Wolf-Rayet
star content. Our sample will be the largest and best-ever
Supercluster/Wolf Rayet sample, an excellent local proxy for
characterizing starburst galaxies' Superclusters.

COS/FUV 11625

Beyond the Classical Paradigm of Stellar Winds: Investigating
Clumping, Rotation and the Weak Wind Problem in SMC O Stars

SMC O stars provide an unrivaled opportunity to probe star formation,
evolution, and the feedback of massive stars in an environment similar
to the epoch of the peak in star formation history. Two recent
breakthroughs in the study of hot, massive stars have important
consequences for understanding the chemical enrichment and buildup of
stellar mass in the Universe. The first is the realization that
rotation plays a major role in influencing the evolution of massive
stars and their feedback on the surrounding environment. The second is
a drastic downward revision of the mass loss rates of massive stars
coming from an improved description of their winds. STIS spectroscopy
of SMC O stars combined with state-of-the-art NLTE analyses has shed
new light on these two topics. A majority of SMC O stars reveal CNO-
cycle processed material brought at their surface by rotational
mixing. Secondly, the FUV wind lines of early O stars provide strong
indications of the clumped nature of their wind. Moreover, we first
drew attention to some late-O dwarfs showing extremely weak wind
signatures. Consequently, we have derived mass loss rates from STIS
spectroscopy that are significantly lower than the current theoretical
predictions used in evolutionary models. Because of the limited size
of the current sample (and some clear bias toward stars with
sharp-lined spectra), these results must however be viewed as
tentative. Thanks to the high efficiency of COS in the FUV range, we
propose now to obtain high-resolution FUV spectra with COS of a larger
sample of SMC O stars to study systematically rotation and wind
properties of massive stars at low metallicity. The analysis of the
FUV wind lines will be based on our 2D extension of CMFGEN to model
axi-symmetric rotating winds.

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.

WFC3/ACS/IR 11600

Star Formation, Extinction, and Metallicity at 0.7z1.5: H-Alpha
Fluxes and Sizes from a Grism Survey of GOODS-N

The global star formation rate (SFR) is ~10x higher at z=1 than today.
This could be due to drastically elevated SFR in some fraction of
galaxies, such as mergers with central bursts, or a higher SFR across
the board. Either means that the conditions in z=1 star forming
galaxies could be quite different from local objects. The next step
beyond measuring the global SFR is to determine the dependence of SFR,
obscuration, metallicity, and size of the star-forming region on
galaxy mass and redshift. However, SFR indicators at z=1 typically
apply local calibrations for UV, [O II] and far-IR, and do not agree
with each other on a galaxy-by-galaxy basis. Extinction, metallicity,
and dust properties cause uncontrolled offsets in SFR calibrations.
The great missing link is Balmer H-alpha, the most sensitive probe of
SFR. We propose a slitless WFC3/G141 IR grism survey of GOODS-N, at 2
orbits/pointing. It will detect Ha+[N II] emission from 0.7z1.5, to
L(Ha) = 1.7 x 10^41 erg/sec at z=1, measuring H-alpha fluxes and sizes
for 600 galaxies, and a small number of higher-redshift emitters.
This will produce: an emission-line redshift survey unbiased by
magnitude and color selection; star formation rates as a function of
galaxy properties, e.g. stellar mass and morphology/mergers measured
by ACS; comparisons of SFRs from H-alpha to UV and far-IR indicators;
calibrations of line ratios of H-alpha to important nebular lines such
as [O II] and H-beta, measuring variations in metallicity and
extinction and their effect on SFR estimates; and the first
measurement of scale lengths of the H-alpha emitting, star- forming
region in a large sample of z~1 sources.

WFC3/ACS/UVIS/IR 11570

Narrowing in on the Hubble Constant and Dark Energy

A measurement of the Hubble constant to a precision of a few percent
would be a powerful aid to the investigation of the nature of dark
energy and a potent "end-to end" test of the present cosmological
model. In Cycle 15 we constructed a new streamlined distance ladder
utilizing high- quality type Ia supernova data and observations of
Cepheids with HST in the near-IR to minimize the dominant sources of
systematic uncertainty in past measurements of the Hubble constant and
reduce its total uncertainty to a little under 5%. Here we propose to
exploit this new route to reduce the remaining uncertainty by more
than 30%, translating into an equal reduction in the uncertainty of
the equation of state of dark energy. We propose three sets of
observations to reach this goal: a mosaic of NGC 4258 with WFC3 in
F160W to triple its sample of long period Cepheids, WFC3/F160W
observations of the 6 ideal SN Ia hosts to triple their samples of
Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN
2007af, to discover and measure its Cepheids and begin expanding the
small set of SN Ia luminosity calibrations. These observations would
provide the bulk of a coordinated program aimed at making the
measurement of the Hubble constant one of the leading constraints on
dark energy.

WFC3/UVI/IR 11557

The Nature of Low-Ionization BAL QSOs

The rare subclass of optically-selected QSOs known as low-ionization
broad absorption line (LoBAL) QSOs show signs of high-velocity gas
outflows and reddened continua indicative of dust obscuration. Recent
studies show that galaxies hosting LoBAL QSOs tend to be ultraluminous
infrared systems that are undergoing mergers, and that have dominant
young ( 100 Myr) stellar populations. Such studies support the idea
that LoBAL QSOs represent a short- lived phase early in the life of
QSOs, when powerful AGN-driven winds are blowing away the dust and gas
surrounding the QSO. If so, understanding LoBALs would be critical in
the study of phenomena regulating black hole and galaxy evolution,
such as AGN feedback and the early stages of nuclear accretion. These
results, however, come from very small samples that may have serious
selection biases. We are therefore taking a more aggressive approach
by conducting a systematic multiwavelength study of a volume limited
sample of LoBAL QSOs at 0.5 z 0.6 drawn from SDSS. We propose to
image their host galaxies in two bands using WFC3/UVIS and WFC3/IR to
study the morphologies for signs of recent tidal interactions and to
map their interaction and star forming histories. We will thus
determine whether LoBAL QSOs are truly exclusively found in young
merging systems that are likely to be in the early stages of nuclear
accretion.

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 21 21
FGS REAcq 23 23
OBAD with Maneuver 17 17

SIGNIFICANT EVENTS: (None)