Notice: Due to the conversion of some ACS WFC or HRC observations into

WFPC2, or NICMOS observations after the loss of ACS CCD science

capability in January, there may be an occasional discrepancy between a

proposal's listed (and correct) instrument usage and the abstract that

follows it.

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT       # 4486

PERIOD COVERED: UT November 08, 2007 (DOY 312)

OBSERVATIONS SCHEDULED

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 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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 DARKs. 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

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

passages leave different imprints on the NICMOS detectors.

NIC2 10755

Photometric Standard Clusters for Cross-Observatory Calibration

The goal of this program is to obtain NICMOS photometry of selected

solar analog stars in selected Galactic clusters that will be used as

on-orbit photometric standard star fields for JWST-NIRCAM. The

availability of such fields at JWST launch will facilitate rapid

photometric calibration of NIRCAM. The NIRCAM team plans to observe the

chosen clusters with Spitzer-IRAC.

WFPC2 10925

Imaging the Nearest Damped Lyman Alpha Absorbers

We propose to acquire broad-band and H-alpha imaging of three bright,

very nearby host galaxies for damped Ly-alpha absorbers {DLAs}. Our

targets are the only DLA hosts at z < 0.03 {i.e., spatial resolutions of

< 1.2 kpc}. The purpose of these observations is to discover the

detailed morphology and kinematics and thus the origins of the gas

giving rise to DLAs. While ground-based spectroscopy of DLAs is used to

infer indirectly the evolution of galaxy metallicity and thick disk

kinematics out to z > 4, only with HST imaging of the very lowest

redshift DLA galaxies can we discover these relationships directly. In

conjunction with H I 21-cm VLA emission maps, broad-band and H-alpha

images of these DLAs will allow us to determine: {1} the sites of active

star formation in the host galaxies and their relationship to the QSO

sightline, {2} the presence of stellar streams, supernova shells, or

bipolar "superwind" outflows in DLA host galaxies, and {3} the detailed

spiral structure of the host galaxies, which will allow us to use the

lower resolution H I 21-cm emission line images to determine unambiguous

DLA kinematics with respect to the host galaxy {i.e., is the DLA

rotating with the disk?}. Thus, the high resolution imaging will allow

us to correctly interpret the kinematics and metallicity information

provided by the H I 21-cm VLA maps and HST UV spectroscopy to better

inform the high-z results.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey of

a sample of 125 very X-ray luminous clusters in the redshift range

0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14

and Cycle15 these systems frequently exhibit strong gravitational

lensing as well as spectacular examples of violent galaxy interactions.

The proposed observations will provide important constraints on the

cluster mass distributions, the physical nature of galaxy-galaxy and

galaxy-gas interactions in cluster cores, and a set of optically bright,

lensed galaxies for further 8-10m spectroscopy. All of our primary

science goals require only the detection and characterization of

high-surface-brightness features and are thus achievable even at the

reduced sensitivity of WFPC2. Because of their high redshift and thus

compact angular scale our target clusters are less adversely affected by

the smaller field of view of WFPC2 than more nearby systems.

Acknowledging the broad community interest in this sample we waive our

data rights for these observations. Due to a clerical error at STScI our

approved Cycle15 SNAP program was barred from execution for 3 months and

only 6 observations have been performed to date - reinstating this SNAP

at Cycle16 priority is of paramount importance to reach meaningful

statistics.

WFPC2 11134

WFPC2 Tidal Tail Survey: Probing Star Cluster Formation on the Edge

The spectacular HST images of the interiors of merging galaxies such as

the Antennae and NGC 7252 have revealed rich and diverse populations of

star clusters created over the course of the interaction. Intriguingly,

our WFPC2 study of tidal tails in these and other interacting pairs has

shown that star cluster birth in the tails does not follow a similarly

straightforward evolution. In fact, cluster formation in these

relatively sparse environments is not guaranteed -- only one of six

tails in our initial study showed evidence for a significant population

of young star clusters. The tail environment thus offers the opportunity

to probe star cluster formation on the edge of the physical parameter

space {e.g., of stellar and gas mass, density, and pressure} that

permits it to occur. We propose to significantly extend our pilot sample

of optically bright, gas-rich tidal tails by a factor of 4 in number to

include a more diverse population of tails, encompassing major and minor

mergers, gas-rich and gas-poor tails, as well as early, late, and merged

interaction stages. With 21 orbits of HST WFPC2 imaging in the F606W and

F814W filters, we can identify, roughly age-date, and measure sizes of

star clusters to determine what physical parameters affect star cluster

formation. WFPC2 imaging has been used effectively in our initial study

of four mergers, and it will be possible in this program to reach

similar limits of Mv=-8.5 for each of 16 more tails. With the much

larger sample we expect to isolate which factors, such as merger stage,

HI content, and merger mass ratio, drive the formation of star clusters.

WFPC2 11307

Completing the ACS Nearby Galaxy Survey with WFPC2

We are requesting 25 orbits of Director's Discretionary Time to complete

the primary science goals of our highly-ranked ACS Nearby Galaxy Survey

Treasury program {ANGST}. Our program lost ~2/3 of its orbits due to the

ACS failure. Roughly half of these were restored as a result of an

appeal to the Telescope Time Review Board which re-scoped the program.

The Board's response to our appeal was explicit in terms of which

targets were to be observed and how. We were directed to request

Director's discretionary time for the components of the appeal which

were not granted by the Review Board, but which were vital to the

success of the program. The observing strategy for ANGST is two-fold: to

obtain one deep field per galaxy which enables derivation of an accurate

ancient star formation history, and to obtain radial tilings sufficient

for recovering the full star formation history. The Review Board granted

WFPC2 observations for deep fields in 7 galaxies, but no time for radial

tilings. However, recovering the full star formation history of a galaxy

is not possible without additional radial coverage. We have searched the

archives for observations which may be used in place of the tilings

{conceding some of the Treasury goals, but providing significant

constraints on the full star formation history}, and have identified

suitable observations for all but two of the galaxies. Here we request

DD time for radial tilings for those last two galaxies.

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               09                 09                   

FGS REacq               05                 05                   

OBAD with Maneuver 30                 30                    

SIGNIFICANT EVENTS: (None)