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 z>6 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 are: (1) Detect Lya

in ~100 galaxies with z>5.6 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 0.5<z<1.8 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

0.5<z<2.2; 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 0.7<z<1.5: 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 0.7<z<1.5, 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 0.3<z<2.7

Using HST and Spitzer

We aim to determine physical properties of IR luminous galaxies at

0.3<z<2.7 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 (0.3<z<2.7). 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 0.3<z<2.7, and establish if major mergers are the drivers

of z>1 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)