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      # 4446

PERIOD COVERED: UT September 12, 2007 (DOY 255)

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 11329

The Final SHOE; Completing a Rich Cepheid Field in NGC 1309

The Cycle 15 SHOES program {GO 10802} is a large HST program allocated

186 orbits to rebuild the distance ladder using NGC 4258 as a new

anchor, a set of 6 recent, ideal type Ia supernovae and Cepheids in

their hosts, and NICMOS as a single, homogeneous photometer of long

period Cepheids. These tools provide the means to achieve a 4%

measurement of the Hubble constant, an invaluable constraint for cosmic

concordance fits to dark energy models. Unfortunately, the SHOES NICMOS

integrations of long period Cepheids in the last and most recent nearby

type Ia supernova host, NGC 1309, are too short because the preliminary

estimate of its distance, 30 Mpc, was too low. Our refined estimate now

based on the full reduction of both our Cycle 14 and 15 ACS data is 36

Mpc, or 0.4 mag farther. Fortunately, Nature was extremely kind

providing a single rich NIC2 field in which we can fully make up for the

shortfall due to its abundance of Cepheids. We are expensing our final 4

orbits on this field of a dozen P>30 day Cepheids and seek an additional

5 orbits to reach the depth for measuring the mean F160W magnitudes of

the long-period Cepheids with the necessary signal-to-noise ratios of

better than 10.

S/C 11163

Accreting Pulsating White Dwarfs in Cataclysmic Variables

Recent ground-based observations have increased the number of known

pulsating white dwarfs in close binaries with active mass transfer

{cataclysmic variables} from 5 to 11 systems. Our past Cycles 8 and 11

STIS observations of the first 2 known, followed by our Cycle 13 SBC

observations of the next 3 discovered, revealed the clear presence of

the white dwarf and increased amplitude of the pulsations in the UV

compared to the optical. The temperatures derived from the UV spectra

show 4 systems are much hotter than non- interacting pulsating white

dwarfs. A larger sample is needed to sort out the nature of the

instability strip in accreting pulsators i.e. whether effects of

composition and rotation due to accretion result in a well-defined

instability strip as a function of Teff.

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.

WFPC2 11038

Narrow Band and Ramp Filter Closeout

These observations are to improve calibration of narrow band and ramp

filters. We also test for changes in the filter properties during

WFPC2's 14 years on-board HST.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of

Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens a

window into dynamical conditions in the protoplanetary disk where they

formed as well as the history of subsequent events which sculpted the

outer Solar System and emplaced them onto their present day heliocentric

orbits. To date, at least 47 TNBs have been discovered, but only about a

dozen have had their mutual orbits and separate colors determined,

frustrating their use to investigate numerous important scientific

questions. The current shortage of data especially cripples scientific

investigations requiring statistical comparisons among the ensemble

characteristics. We propose to obtain sufficient astrometry and

photometry of 23 TNBs to compute their mutual orbits and system masses

and to determine separate primary and secondary colors, roughly tripling

the sample for which this information is known, as well as extending it

to include systems of two near-equal size bodies. To make the most

efficient possible use of HST, we will use a Monte Carlo technique to

optimally schedule our observations.

WFPC2 11218

Snapshot Survey for Planetary Nebulae in Globular Clusters of the Local

Group

Planetary nebulae {PNe} in globular clusters {GCs} raise a number of

interesting issues related to stellar and galactic evolution. The number

of PNe known in Milky Way GCs, 4, is surprisingly low if one assumes

that all stars pass through a PN stage. However, it is likely that the

remnants of stars now evolving in Galactic GCs leave the AGB so slowly

that any ejected nebula dissipates long before the star becomes hot

enough to ionize it. Thus there should not be ANY PNe in Milky Way

GCs--but there are four! It has been suggested that these PNe are the

result of mergers of binary stars within GCs, i.e., that they are

descendants of blue stragglers. The frequency of occurrence of PNe in

external galaxies poses more questions, because it shows a range of

almost an order of magnitude. I propose a Snapshot survey aimed at

discovering PNe in the GC systems of Local Group galaxies more distant

than the Magellanic Clouds. These clusters, some of which may be much

younger than their counterparts in the Milky Way, might contain many

more PNe than those of our own galaxy. I will use the standard technique

of emission-line and continuum imaging, which easily discloses PNe.

WFPC2 11222

Direct Detection and Mapping of Star Forming Regions in Nearby, Luminous

Quasars

We propose to carry out narrow-band emission line imaging observations

of 8 quasars at z=0.05-0.15 with the WFPC2 ramp filters and with the

NICMOS narrow-band filters. We will obtain images in the [O II], [O

III], H-beta, and Pa-alpha emission line bands to carry out a series of

diagnostic tests aimed at detecting and mapping out star-forming regions

in the quasar host galaxies. This direct detection of star-forming

regions will confirm indirect indications for star formation in quasar

host galaxies. It will provide a crucial test for models of quasar and

galaxy evolution, that predict the co-existence of starbursts and

"monsters" and will solve the puzzle of why different indicators of star

formation give contradictory results. A secondary science goal is to

assess suggested correlations between quasar luminosity and the size of

the narrow-line region.

WFPC2 11289

SL2S: The Strong Lensing Legacy Survey

Recent systematic surveys of strong galaxy-galaxy lenses {CLASS, SLACS,

GOODS, etc.} are producing spectacular results for galaxy masses roughly

below a transition mass M~10^13 Mo. The observed lens properties and

their evolution up to z~0.2, consistent with numerical simulations, can

be described by isothermal elliptical potentials. In contrast, modeling

of giant arcs in X-ray luminous clusters {halo masses M >~10^13 Mo}

favors NFW mass profiles, suggesting that dark matter halos are not

significantly affected by baryon cooling. Until recently, lensing

surveys were neither deep nor extended enough to probe the intermediate

mass density regime, which is fundamental for understanding the assembly

of structures. The CFHT Legacy Survey now covers 125 square degrees, and

thus offers a large reservoir of strong lenses probing a large range of

mass densities up to z~1. We have extracted a list of 150 strong lenses

using the most recent CFHTLS data release via automated procedures.

Following our first SNAPSHOT proposal in cycle 15, we propose to

continue the Hubble follow-up targeting a larger list of 130 lensing

candidates. These are intermediate mass range candidates {between

galaxies and clusters} that are selected in the redshift range of 0.2-1

with no a priori X-ray selection. The HST resolution is necessary for

confirming the lensing candidates, accurate modeling of the lenses, and

probing the total mass concentration in galaxy groups up to z~1 with the

largest unbiased sample available to date.

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                08                 08        

FGS REacq                07                 07        

OBAD with Maneuver  30                 30              

SIGNIFICANT EVENTS: (None)