HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

 

DAILY REPORT      # 4506

 

PERIOD COVERED: UT December 12, 2007 (DOY 346)

 

OBSERVATIONS SCHEDULED

 

ACS/SBC 11309

 

Chemical Composition of an Exo-Neptune

 

The recent discovery that the Neptune-like exoplanet GJ 436 b transits

its host star has presented us the first chance to observationally study

ice giant formation beyond our solar system {Gillon et al. 2007}. Using

Directors Discretionary time, we propose to obtain a high-precision

light curve of the GJ 436 b transit with the FGS in order to improve the

current radius determination for this planet. Measuring a precise radius

for GJ 436 b will allow us to ascertain whether the planet has a pure

water vapor or H/He envelope like Uranus and Neptune. Knowing this will

constrain its formation and evolution and help place our own solar

system ice giants in a broader context. Additionally, a precise radius

for GJ 436 b will be a necessity for interpreting the certain follow-up

observations of this unique system.

 

WFPC2 10886

 

The Sloan Lens ACS Survey: Towards 100 New Strong Lenses

 

As a continuation of the highly successful Sloan Lens ACS {SLACS} Survey

for new strong gravitational lenses, we propose one orbit of ACS-WFC

F814W imaging for each of 50 high-probability strong galaxy-galaxy lens

candidates. These observations will confirm new lens systems and permit

immediate and accurate photometry, shape measurement, and mass modeling

of the lens galaxies. The lenses delivered by the SLACS Survey all show

extended source structure, furnishing more constraints on the projected

lens potential than lensed-quasar image positions. In addition, SLACS

lenses have lens galaxies that are much brighter than their lensed

sources, facilitating detailed photometric and dynamical observation of

the former. When confirmed lenses from this proposal are combined with

lenses discovered by SLACS in Cycles 13 and 14, we expect the final

SLACS lens sample to number 80--100: an approximate doubling of the

number of known galaxy-scale strong gravitational lenses and an

order-of-magnitude increase in the number of optical Einstein rings. By

virtue of its homogeneous selection and sheer size, the SLACS sample

will allow an unprecedented exploration of the mass structure of the

early-type galaxy population as a function of all other observable

quantities. This new sample will be a valuable resource to the

astronomical community by enabling qualitatively new strong lensing

science, and as such we will waive all but a short {3-month} proprietary

period on the observations.

 

NIC1 10889

 

The Nature of the Halos and Thick Disks of Spiral Galaxies

 

We propose to resolve the extra-planar stellar populations of the thick

disks and halos of seven nearby, massive, edge-on galaxies using ACS,

NICMOS, and WFPC2 in parallel. These observations will provide accurate

star counts and color-magnitude diagrams 1.5 magnitudes below the tip of

the Red Giant Branch sampled along the two principal axes and one

intermediate axis of each galaxy. We will measure the metallicity

distribution functions and stellar density profiles from star counts

down to very low average surface brightnesses, equivalent to ~32 V-mag

per square arcsec. These observations will provide the definitive HST

study of extra-planar stellar populations of spiral galaxies. Our

targets cover a range in galaxy mass, luminosity, and morphology and as

function of these galaxy properties we will provide: - The first

systematic study of the radial and isophotal shapes of the diffuse

stellar halos of spiral galaxies - The most detailed comparative study

to date of thick disk morphologies and stellar populations - A

comprehensive analysis of halo and thick disk metallicity distributions

as a function of galaxy type and position within the galaxy. - A

sensitive search for tidal streams - The first opportunity to directly

relate globular cluster systems to their field stellar population We

will use these fossil records of the galaxy assembly process preserved

in the old stellar populations to test halo and thick disk formation

models within the hierarchical galaxy formation scheme. We will test

LambdaCDM predictions on sub-galactic scales, where it is difficult to

test using CMB and galaxy redshift surveys, and where it faces its most

serious difficulties.

 

NIC1/NIC2/NIC3 8795

 

NICMOS Post-SAA calibration - CR Persistence Part 6

 

A new procedure proposed to alleviate the CR-persistence problem of

NICMOS. Dark frames will be obtained immediately upon exiting the SAA

contour 23, and every time a NICMOS exposure is scheduled within 50

minutes of coming out of the SAA. The darks will be obtained in parallel

in all three NICMOS Cameras. The POST-SAA darks will be non- standard

reference files available to users with a USEAFTER date/time mark. The

keyword 'USEAFTER=date/time' will also be added to the header of each

POST-SAA DARK frame. The keyword must be populated with the time, in

addition to the date, because HST crosses the SAA ~8 times per day so

each POST-SAA DARK will need to have the appropriate time specified, for

users to identify the ones they need. Both the raw and processed images

will be archived as POST-SAA DARKSs. Generally we expect that all NICMOS

science/calibration observations started within 50 minutes of leaving an

SAA will need such maps to remove the CR persistence from the science i

mages. Each observation will need its own CRMAP, as different SAA

passages leave different imprints on the NICMOS detectors.

 

NIC3 11191

 

NICMOS Imaging of a z>4 High-Redshift Ultraluminous Submillimeter Source

 

We propose 16 orbits of deep NICMOS 1.6 um imaging of GOODS850-5, a

unique z>4 candidate SCUBA source that is bright in the submillimeter

{submm} but extremely faint at all other wavelengths. GOODS850-5 is a 11

mJy 850 um source discovered in our GOODS- N SCUBA survey. It does not

have a radio counterpart and its accurate location was recently

determined with the SMA interferometer. It is not detected by the

GOODS-N HST ACS imaging and is just above the detection limit of the

ultradeep Spitzer imaging at 3.6-24 um. Its faint radio flux and its

Spitzer color suggest a redshift of z>4, and potentially even z>6. It

has an incredible star formation rate of ~1000 solar mass per year, and

it can quickly grow into a >10^11 solar mass massive galaxy. Radio faint

submm sources like GOODS850-5 may be a new population of high-redshift

massive galaxies that are not picked up by any of the previous optical,

near-IR, and radio surveys, and therefore it is crucial to obtain the

redshift of GOODS850-5. However, because of its extreme optical

faintness, the only way to constrain its redshift is photometric

redshift with the existing Spitzer photometry and the proposed NICMOS

1.6 um photometry. NICMOS is the only instrument that can provide

information about its redshift and morphology among all space- based and

ground-based instruments at all wavelengths. The proposed observation

will provide unique insight on galaxy evolution and mass assembly at

high redshift.

 

WEPC2 11196

 

An Ultraviolet Survey of Luminous Infrared Galaxies in the Local

Universe

 

At luminosities above 10^11.4 L_sun, the space density of far-infrared

selected galaxies exceeds that of optically selected galaxies. These

Luminous Infrared Galaxies {LIRGs} are primarily interacting or merging

disk galaxies undergoing starbursts and creating/fueling central AGN. We

propose far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV imaging of a

sample of 27 galaxies drawn from the complete IRAS Revised Bright Galaxy

Sample {RBGS} LIRGs sample and known, from our Cycle 14 B and I-band ACS

imaging observations, to have significant numbers of bright {23 < B < 21

mag} star clusters in the central 30 arcsec. The HST UV data will be

combined with previously obtained HST, Spitzer, and GALEX images to {i}

calculate the ages of the clusters as function of merger stage, {ii}

measure the amount of UV light in massive star clusters relative to

diffuse regions of star formation, {iii} assess the feasibility of using

the UV slope to predict the far- IR luminosity {and thus the star

formation rate} both among and within IR-luminous galaxies, and {iv}

provide a much needed catalog of rest-frame UV morphologies for

comparison with rest-frame UV images of high-z LIRGs and Lyman Break

Galaxies. These observations will achieve the resolution required to

perform both detailed photometry of compact structures and spatial

correlations between UV and redder wavelengths for a physical

interpretation our IRX-Beta results. The HST UV data, combined with the

HST ACS, Spitzer, Chandra, and GALEX observations of this sample, will

result in the most comprehensive study of luminous starburst galaxies to

date.

 

WFPC2 10915

 

ACS Nearby Galaxy Survey

 

Existing HST observations of nearby galaxies comprise a sparse and

highly non-uniform archive, making comprehensive comparative studies

among galaxies essentially impossible. We propose to secure HST's

lasting impact on the study of nearby galaxies by undertaking a

systematic, complete, and carefully crafted imaging survey of ALL

galaxies in the Local Universe outside the Local Group. The resulting

images will allow unprecedented measurements of: {1} the star formation

history {SFH} of a >100 Mpc^3 volume of the Universe with a time

resolution of Delta[log{t}]=0.25; {2} correlations between spatially

resolved SFHs and environment; {3} the structure and properties of thick

disks and stellar halos; and {4} the color distributions, sizes, and

specific frequencies of globular and disk clusters as a function of

galaxy mass and environment. To reach these goals, we will use a

combination of wide-field tiling and pointed deep imaging to obtain

uniform data on all 72 galaxies within a volume-limited sample extending

to ~3.5 Mpc, with an extension to the M81 group. For each galaxy, the

wide-field imaging will cover out to ~1.5 times the optical radius and

will reach photometric depths of at least 2 magnitudes below the tip of

the red giant branch throughout the limits of the survey volume. One

additional deep pointing per galaxy will reach SNR~10 for red clump

stars, sufficient to recover the ancient SFH from the color-magnitude

diagram. This proposal will produce photometric information for ~100

million stars {comparable to the number in the SDSS survey} and uniform

multi- color images of half a square degree of sky. The resulting

archive will establish the fundamental optical database for nearby

galaxies, in preparation for the shift of high- resolution imaging to

the near-infrared.

 

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:

18162-2 - FSW 3.1B RAM Installation

18054-0 - Preview KF Sun Vector data via Telemetry Diags

 

 

COMPLETED OPS NOTES: (None)

 

                      SCHEDULED      SUCCESSFUL  

FGS GSacq               06                 06                           

FGS REacq               08                 08                               

OBAD with Maneuver 26                 26                    

 

SIGNIFICANT EVENTS:

 

FSW 3.1 Release B was successfully installed in HST486 RAM. The 3.1B RAM

loads were completed at 346/11:59:33. The patch operation to activate FSW 3.1

Release B was executed during M2G mode at 346/14:01:28, which

initialized FSW 3.1B in VSS operations. After software activation A and

T formats were monitored to ensure telemetry was nominal. The post

installation RAM memory dump was completed at 346/15:30:00 and verified

by FSW. The database value for Hybrid mode KG (Zero the CT nutation

radius) was patched at 346/15:39:02.