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HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5204

PERIOD COVERED: 8:00pm October 12 - 7:59pm October 13, 2010 (DOY 286/00:00z-286/23:59z)

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS:

HSTARS for DOY 270

12465 - REAcq(2,3,3) at 270/15:09:14 required two attempts to achieve CT-DV on FGS2.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       Scheduled   Successful

FGS GSAcq               9              9        

FGS REAcq               7              7        

OBAD with Maneuver 7              7        

SIGNIFICANT EVENTS: (None)

OBSERVATIONS SCHEDULED:

ACS/WFC 11996

CCD Daily Monitor (Part 3)

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 308 orbits (19.25 weeks) from 21 June 2010 to 1 November

2010.

COS/NUV 12264

The Relationship between Gas and Galaxies for 0<z<1.2

The way in which gas cools and contracts into gravitational potentials

dominated by dark matter to form stars (and hence galaxies), and the way

in which these stars and their deaths then affect the incoming gas, is a

topic of great importance and high current interest. It was also

recognized as a key science goal for HST by some of its original

builders such as Bahcall, Spitzer and Salpeter. We propose to use COS to

complement and extend the planned COS GTO and GO surveys by extending to

higher redshifts (z<1.2), and also by substantially increasing the

redshift pathlength within which both the gas and the galaxy

distributions are known. We will do this by observing the lines-of-sight

to four carefully selected QSOs in regions of the sky with extensive

deep galaxy redshift surveys (VVDS and GDDS) already in place. This will

allow us to study the evolution in the relationship between gas and

galaxies over the second half of the history of the Universe and over a

large range of physical scales. By comparing with independent,

state-of-the-art hydrodynamic cosmological models, we will test our

understanding of the formation of galaxies, and determine whether the

AGN and supernova feedback prescriptions currently used in these

simulations are correct. It is likely that only by using the combination

of absorption line information from hydrogen and metals, with large

galaxy samples, that the complexities of the feedback process can be

unscrambled. We have assembled a strong consortium of experts in HST

absorption line analysis, deep galaxy redshift surveys, and cosmological

simulations including baryons. With this team, and the proposed

observations, we are confident that our understanding of galaxy

formation and evolution can be significantly improved.

COS/NUV/FUV 12178

Spanning the Reionization History of IGM Helium: a Highly Efficient

Spectral Survey of the Far-UV-Brightest Quasars

The reionization of IGM helium likely occurred at redshifts of z=3 to 4.

Detailed studies of HeII Ly-alpha absorption toward a handful of quasars

at 2.7<z<3.3 confirm the potential of such IGM probes, but the small

sample and redshift range limited confidence in cosmological inferences.

The requisite unobscured sightlines to high redshift are extremely rare;

but we've cross-correlated 10, 000 z>2.8 SDSS DR7 (and other) quasars

with GALEX GR4/5, to identify 630 candidates potentially useful for HST

HeII studies. Our cycle 15-16 HST trials confirm our approach, verifying

twenty new HeII quasars at unprecedented 40% efficiency. We propose to

complete the first efficient (80% with refinements) survey for HeII

quasars, via reconnaissance (~1 orbit) COS spectra of a highly select

subset of 17 SDSS/GALEX quasars at 2.7<z<3.8. Along with past work, this

program will yield 3-4 of the brightest far-UV HeII sightlines within

each of 10-12 redshift bins spanning 2.7<z<3.8, enabling a community

sample suitable for detailed spectral follow-up with HST. Herein, we

will also directly obtain quality UV spectral stacks within each

redshift bin to trace the reionization history of IGM helium; such

spectral stacks average over cosmic variance and individual object

pathology. Our high-yield HeII sightline sample and spectral stacks will

enable confident conclusions about the IGM baryon density, the spectrum

and evolution of the ionizing background, the evolution of HeII opacity,

and the epoch of helium reionization.

STIS/CCD 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 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.

WFC3/IR 12224

Measuring the Stellar Populations of Individual Lyman Alpha Emitters

During the Epoch of Peak Star Formation

Selecting galaxies by their strong Lyman-alpha emission provides a

powerful means of probing the reionization epoch and the faint/low-mass

galaxies that dominate star formation at high redshift. Yet, our

understanding of high-redshift Lyman-alpha emitters (LAEs) has lagged

behind that of other well-studied populations (e.g., Lyman break

galaxies) due to their continuum faintness and the shifting of

age/mass-sensitive features into the near-IR where the high terrestrial

background inhibits deep observations. All existing studies of LAEs at

z>2 have used stacked optical and/or Spitzer infrared data to discern

their median properties, but the actual distributions of ages,

reddenings, and stellar masses for these populations are poorly

characterized. To fill this glaring gap in the observations and advance

our understanding of this important population, we propose WFC3/IR+F160W

imaging of fields where we have conducted a survey of low redshift

(z~1.9) Lyman-alpha emitters (LAEs), in order to measure their ages and

stellar masses at an epoch where such observations directly probe the

age-sensitive Balmer/4000 AA breaks. The targeted sample will include

45-50 spectroscopically confirmed LAEs at z=1.7-2.1 and roughly twice as

many candidates, making it the largest sample of homogeneously selected

LAEs with individual measurements of the ages, masses, and dust

extinction. With these data we will (1) carefully take into account the

age-dependence of the extinction curve to make robust comparisons

between LAEs and continuum-selected galaxies at the same redshifts; (2)

combine clustering and stellar mass measurements to infer the duty

cycles of LAEs and determine if they are triggered in the presence of

large-scale structures; and (3) quantify the importance of the LAE phase

at different galaxy luminosity and mass scales, over a large dynamic

range in these properties. An economical investment of just 12 orbits

will allow us to accomplish these goals, and remains the only hope of

efficiently studying such low luminosity high-redshift galaxies in the

near-IR prior to the JWST-era.

WFC3/IR 12283

WFC3 Infrared Spectroscopic Parallel Survey (WISP): A Survey of Star

Formation Across Cosmic Time

We will use the unique power of WFC3 slitless spectroscopy to measure

cosmic star formation across its peak epoch. The broad, continuous,

spectral coverage of the G102 and G141 grisms provides the best

currently feasible measurement of the star formation rate continuously

from 0.5<z<2.5, over which ground-based searches are severely limited.

Our Cycle 17 pure-parallel grism program has proven efficient for

identifying line emission from galaxies across this large fraction of

cosmic time. With less than two months of WFC3 observing completed, our

new measurements have more than doubled the sample of emission-line

galaxies that we found over the entire NICMOS Parallel Grism program. We

propose to extend this cost-effective WFC3 Survey by using 280 orbits of

pure parallel grism spectroscopy in 50 deep (4-5 orbit) fields with both

G102 and G141, and 40 shallow (2-3 orbit) fields with G141 alone. This

will complete a sample of 2000-3000 emission line galaxies in the

"redshift desert" and search for serendipitous Lya emitters at z>5.5.

Our primary science goals are: (1) Measure ratios of bright emission

lines ([OII], [OIII], Ha, and Hb) in a substantial fraction of these

galaxies, thereby estimating dust and metallicity evolution in a sample

of galaxies that is not biased by photometric selection. (2) Derive an

extinction-corrected Ha luminosity function, with a 20 times larger

sample than our previous NICMOS results. (3) Measure the

mass-metallicity relation at crucial intermediate redshifts, with the

support of our ongoing ground-based, follow-up, observing program (4)

Determine the spectroscopic close pair fraction in this sample, in order

to constrain hierarchal merging models (5) Uncover a new sample of

obscured AGN at these redshifts and, (6) Use the Balmer break diagnostic

to constrain the ages of continuum detected sources down to H = 25.

As a bonus, these observations will be sensitive to Lya emission at

z>5.5, taking advantage of continuous spectral coverage to observe large

volumes for luminous galaxies at the highest redshifts. Over Cycles 17

and 18, we expect to detect 5-20 LAEs over redshifts spanning 5.5 < z <

7.5. These observations will likely place the most stringent constraint

on the numbers of z>6.5 Lya emitters until JWST. We are waiving all

proprietary rights to our data and will make high-level data products

available through the ST/ECF.

WFC3/IR 12286

Hubble Infrared Pure Parallel Imaging Extragalactic Survey (HIPPIES)

WFC3 has demonstrated its unprecedented power in probing the early

universe. Here we propose to continue our pure parallel program with

this instrument to search for LBGs at z~6--8. Our program, dubbed as the

Hubble Infrared Pure Parallel Imaging Extragalactic Survey ("HIPPIES"),

will carry on the HST pure parallel legacy in the new decade. We request

205 orbits in Cycle-18, which will spread over ~ 50 high Galactic

latitude visits (|b|>20deg) that last for 3 orbits and longer, resulting

a total survey area of ~230 square arcmin. Combining the WFC3 pure

parallel observations in Cycle-17, HIPPIES will complement other

existing and forthcoming WFC3 surveys, and will make unique

contributions to the study in the new redshift frontier because of the

randomness of the survey fields. To make full use of the parallel

opportunities, HIPPIES will also take ACS parallels to study LBGs at

z~5--6. Being a pure parallel program, HIPPIES will only make very

limited demand on the scarce HST resources, but will have potentially

large scientific returns. As in previous cycle, we waive all proprietary

data rights, and will make the enhanced data products public in a timely

manner.

(1) The WFC3 part of HIPPIES aims at the most luminous LBG population at

z~8 and z~7. As its survey fields are random and completely

uncorrelated, the number counts of the bright LBGs from HIPPIES will be

least affected by the "cosmic variance", and hence we will be able to

obtain the best constraint on the bright-end of the LBG luminosity

function at z~8 and 7. Comparing the result from HIPPIES to the

hydrodynamic simulations will test the input physics and provide insight

into the nature of the early galaxies. (2) The z~7--8 candidates from

HIPPIES, most of which will be the brightest ones that any surveys would

be able to find, will have the best chance to be spectroscopically

confirmed at the current 8--10m telescopes. (3) The ACS part of HIPPIES

will produce a significant number of candidate LBGs at z~5 and z~6 per

ACS field. Combining with the existing, suitable ACS fields in the HST

archive, we will be able to utilize the random nature of the survey to

quantify

the cosmic variance and to measure the galaxy bias at z~5--6, and

therefore the galaxy halo masses at these redshifts. (4) We will also

find a large number of extremely red, old galaxies at intermediate

redshifts, and the fine spatial resolution offered by the WFC3 will

enable us constrain their formation history based on the study of their

morphology, and hence shed light on their connection to the very early

galaxies in the universe.

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/IR/UV 12163

Structure and Stellar Content of the Nearest Nuclear Clusters in

Late-Type Spiral Galaxies

HST surveys have shown that nuclear star clusters are nearly ubiquitous

in late-type, bulgeless disk galaxies. In early-type galaxies, the

central black hole mass correlates with the bulge mass and velocity

dispersion, but the relationship between black hole mass and host galaxy

properties in bulgeless galaxies is not yet understood. Some nuclear

clusters (such as the one in M33) do not contain a central massive black

hole at all, while other late-type galaxies (such as NGC 4395) are known

to contain accretion-powered active nuclei within their nuclear

clusters, indicating that a central black hole is present. But, the

overall "occupation fraction" of black holes within nuclear clusters is

largely unconstrained. Measurement of the structure, dynamics, and

stellar content of nuclear star clusters is an important pathway toward

understanding the demographics of low-mass black holes in late-type

galaxies.

We propose to obtain multi-filter WFC3 UV, optical, and near-IR images

of 10 of the nearest and brightest nuclear clusters in late-type spiral

galaxies. We will use the new WFC3 data to measure the cluster radial

profiles, to search for color gradients, and in combination with

ground-based spectroscopy and stellar population modeling, to determine

the stellar masses of the clusters. Since nuclear clusters are known to

contain stellar populations with a wide range of ages, the broad

wavelength coverage of our data will provide new leverage to constrain

the star formation history of the clusters. We will carry out dynamical

modeling for the clusters, using the cluster structural parameters and

stellar M/L ratios measured from the WFC3 data and kinematics measured

from ground-based, adaptive-optics assisted integral-field spectroscopy

(already obtained or approved for 8 of the 10 targets). This will yield

tight new constraints on the masses of intermediate-mass black holes

(IMBH) within the clusters, and may result in the first dynamical

detections of IMBHs in the nuclei of late-type spirals.

WFC3/UV 12215

Searching for the Missing Low-Mass Companions of Massive Stars

Recent results on binary companions of massive O stars appear to

indicate that the distribution of secondary masses is truncated at low

masses. It thus mimics the distribution of companions of G dwarfs and

also the Initial Mass Function (IMF), except that it is shifted upward

by a factor of 20 in mass. These results, if correct, provide a

distribution of mass ratios that hints at a strong constraint on the

star-formation process. However, this intriguing result is derived from

a complex simulation of data which suffer from observational

incompleteness at the low-mass end.

We propose a snapshot survey to test this result in a very direct way.

HST WFC3 images of a sample of the nearest Cepheids (which were formerly

B stars of ~5 Msun) will search for low-mass companions down to M

dwarfs. We will confirm any companions as young stars, and thus true

physical companions, through follow-up Chandra X-ray images. Our survey

will show clearly whether the companion mass distribution is truncated

at low masses, but at a mass much higher than that of the IMF or G

dwarfs.

WFC3/UV 12245

Orbital Evolution and Stability of the Inner Uranian Moons

Nine densely-packed inner moons of Uranus show signs of chaos and

orbital instability over a variety of time scales. Many moons show

measureable orbital changes within a decade or less. Long-term

integrations predict that some moons could collide in less than one

million years. One faint ring embedded in the system may, in fact, be

the debris left behind from an earlier such collision. Meanwhile, the

nearby moon Mab falls well outside the influence of the others but

nevertheless shows rapid, as yet unexplained, changes in its orbit. It

is embedded within a dust ring that also shows surprising variability. A

highly optimized series of observations with WFC3 over the next three

cycles will address some of the fundamental open questions about this

dynamically active system: Do the orbits truly show evidence of chaos?

If so, over what time scales? What can we say about the masses of the

moons involved? What is the nature of the variations in Mab's orbit? Is

Mab's motion predictable or random? Astrometry will enable us to derive

the orbital elements of these moons with 10-km precision. This will be

sufficient to study the year-by-year changes and, combined with other

data from 2003-2007, the decadal evolution of the orbits. The pairing of

precise astrometry with numerical integrations will enable us to derive

new dynamical constraints on the masses of these moons. Mass is the

fundamental unknown quantity currently limiting our ability to reproduce

the interactions within this system. This program will also capitalize

upon our best opportunity for nearly 40 years to study the unexplained

variations in Uranus's faint outer rings.

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/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).