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 # 4461

PERIOD COVERED: UT October 03, 2007 (DOY 276)

OBSERVATIONS SCHEDULED

FGS 11211

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That

measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a

useful result, judged by the over ten refereed citations each year

since. It is, however, unsatisfactory to have the direct,

parallax-based, distance scale of Population II variables based on a

single star. We propose, therefore, to obtain the parallaxes of four

additional RR Lyrae stars and two Population II Cepheids, or W Vir

stars. The Population II Cepheids lie with the RR Lyrae stars on a

common K-band Period-Luminosity relation. Using these parallaxes to

inform that relationship, we anticipate a zero-point error of 0.04

magnitude. This result should greatly strengthen confidence in the

Population II distance scale and increase our understanding of RR Lyrae

star and Pop II Cepheid astrophysics.

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.

NIC2 10857

Are Organics Common in Outer Planetary Systems?

Mixtures of water ice and organics seem to pervade surfaces in the outer

Solar System, from the rings of Saturn to the Kuiper Belt Objects. The

early Earth was bombarded by the leftover planetesimals from the

formation of the planets, and these must have been rich in both ice and

carbon to provide the building blocks of life. Scattered light from

debris disks is remarkably similar in albedo {total scattering

efficiency} and color {red} to the objects in the outer solar system.

Thus, we have a hint that the same photochemical processes that happened

close to home also happen around other stars. We propose to study the

color of two debris disks in some detail. Scattering of light is the

only window available to us to see the composition of debris disks in a

spatially resolved manner and to assess their potential for containing

planets like ours.

NIC3 11107

Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy

Formation in the Early Universe

We have used the ultraviolet all-sky imaging survey currently being

conducted by the Galaxy Evolution Explorer {GALEX} to identify for the

first time a rare population of low- redshift starbursts with properties

remarkably similar to high-redshift Lyman Break Galaxies {LBGs}. These

"compact UV luminous galaxies" {UVLGs} resemble LBGs in terms of size,

SFR, surface brightness, mass, metallicity, kinematics, dust, and color.

The UVLG sample offers the unique opportunity of investigating some very

important properties of LBGs that have remained virtually inaccessible

at high redshift: their morphology and the mechanism that drives their

star formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS

in order to 1} characterize their morphology and look for signs of

interactions and mergers, and 2} probe their star formation histories

over a variety of timescales. The images show a striking trend of

small-scale mergers turning large amounts of gas into vigorous

starbursts {a process referred to as dissipational or "wet" merging}.

Here, we propose to complete our sample of 31 LBG analogs using the

ACS/SBC F150LP {FUV} and WFPC2 F606W {R} filters in order to create a

statistical sample to study the mechanism that triggers star formation

in UVLGs and its implications for the nature of LBGs. Specifically, we

will 1} study the trend between galaxy merging and SFR in UVLGs, 2}

artificially redshift the FUV images to z=1-4 and compare morphologies

with those in similarly sized samples of LBGs at the same rest-frame

wavelengths in e.g. GOODS, UDF, and COSMOS, 3} determine the presence

and morphology of significant stellar mass in "pre-burst" stars, and 4}

study their immediate environment. Together with our Spitzer

{IRAC+MIPS}, GALEX, SDSS and radio data, the HST observations will form

a unique union of data that may for the first time shed light on how the

earliest major episodes of star formation in high redshift galaxies came

about. This proposal was adapted from an ACS HRC+WFC proposal to meet

the new Cycle 16 observing constraints, and can be carried out using the

ACS/SBC and WFPC2 without compromising our original science goals.

WFPC2 11113

Binaries in the Kuiper Belt: Probes of Solar System Formation and

Evolution

The discovery of binaries in the Kuiper Belt and related small body

populations is powering a revolutionary step forward in the study of

this remote region. Three quarters of the known binaries in the Kuiper

Belt have been discovered with HST, most by our snapshot surveys. The

statistics derived from this work are beginning to yield surprising and

unexpected results. We have found a strong concentration of binaries

among low-inclination Classicals, a possible size cutoff to binaries

among the Centaurs, an apparent preference for nearly equal mass

binaries, and a strong increase in the number of binaries at small

separations. We propose to continue this successful program in Cycle 16;

we expect to discover at least 13 new binary systems, targeted to

subgroups where these discoveries can have the greatest impact.

WFPC2 11128

Time Scales Of Bulge Formation In Nearby Galaxies

Traditionally, bulges are thought to fit well into galaxy formation

models of hierarchical merging. However, it is now becoming well

established that many bulges formed through internal, secular evolution

of the disk rather than through mergers. We call these objects

pseudobulges. Much is still unknown about pseudobulges, the most

pressing questions being: How, exactly, do they build up their mass? How

long does it take? And, how many exist? We are after an answer to these

questions. If pseudobulges form and evolve over longer periods than the

time between mergers, then a significant population of pseudobulges is

hard to explain within current galaxy formation theories. A pseudobulge

indicates that a galaxy has most likely not undergone a major merger

since the formation of the disk. The ages of pseudobulges give us an

estimate for the time scale of this quiescent evolution. We propose to

use 24 orbits of HST time to complete UBVIH imaging on a sample of 33

nearby galaxies that we have observed with Spitzer in the mid-IR. These

data will be used to measure spatially resolved stellar population

parameters {mean stellar age, metallicity, and star formation history};

comparing ages to star formation rates allows us to accurately constrain

the time scale of pseudobulge formation. Our sample of bulges includes

both pseudo- and classical bulges, and evenly samples barred and

unbarred galaxies. Most of our sample is imaged, 13 have complete UBVIH

coverage; we merely ask to complete missing observations so that we may

construct a uniform sample for studying bulge formation. We also wish to

compare the stellar population parameters to a variety of bulge and

global galaxy properties including star formation rates, dynamics,

internal bulge morphology, structure from bulge-disk decompositions, and

gas content. Much of this data set is already or is being assembled.

This will allow us to derive methods of pseudobulge identification that

can be used to accurately count pseudobulges in large surveys. Aside

from our own science goals, we will present this broad set of data to

the community. Thus, we waive proprietary periods for all observations.

WFPC2 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still

largely an open problem in cosmology: how does the Universe evolve from

large linear scales dominated by dark matter to the highly non-linear

scales of galaxies, where baryons and dark matter both play important,

interacting, roles? To understand the complex physical processes

involved in their formation scenario, and why they have the tight

scaling relations that we observe today {e.g. the Fundamental Plane}, it

is critically important not only to understand their stellar structure,

but also their dark-matter distribution from the smallest to the largest

scales. Over the last three years the SLACS collaboration has developed

a toolbox to tackle these issues in a unique and encompassing way by

combining new non-parametric strong lensing techniques, stellar

dynamics, and most recently weak gravitational lensing, with

high-quality Hubble Space Telescope imaging and VLT/Keck spectroscopic

data of early-type lens systems. This allows us to break degeneracies

that are inherent to each of these techniques separately and probe the

mass structure of early-type galaxies from 0.1 to 100 effective radii.

The large dynamic range to which lensing is sensitive allows us both to

probe the clumpy substructure of these galaxies, as well as their

low-density outer haloes. These methods have convincingly been

demonstrated, by our team, using smaller pilot-samples of SLACS lens

systems with HST data. In this proposal, we request observing time with

WFPC2 and NICMOS to observe 53 strong lens systems from SLACS, to obtain

complete multi-color imaging for each system. This would bring the total

number of SLACS lens systems to 87 with completed HST imaging and

effectively doubles the known number of galaxy-scale strong lenses. The

deep HST images enable us to fully exploit our new techniques, beat down

low-number statistics, and probe the structure and evolution of

early-type galaxies, not only with a uniform data-set an order of

magnitude larger than what is available now, but also with a fully

coherent and self-consistent methodological approach!

WFPC2 11227

The orbital period for an ultraluminous X-ray source in NGC1313

The ultraluminous X-ray sources {ULXs} are extragalactic point sources

with luminosities that exceed the Eddington luminosity for conventional

stellar-mass black holes by factors of 10 - 100. It has been hotly

debated whether the ULXs are just common stellar-mass black hole sources

with beamed emission or whether they are sub-Eddington sources that are

firmly decide this question, one must obtain dynamical mass measurements

through photometric and spectroscopic monitoring of the secondaries of

these system. The crucial first step is to establish the orbital period

of a ULX, and arguably the best way to achieve this goal is by

monitoring its ellipsoidal light curve. The extreme ULX NGC1313 X-2

provides an outstanding target for an orbital period determination

because its relatively bright optical counterpart {V = 23.5} showed a

15% variation between two HST observations separated by three months.

This level of variability is consistent with that expected for a tidally

distorted secondary star. Here we propose a set of 20 imaging

observations with HST/WFPC2 to define the orbital period. This would be

the first photometric measurement of the orbital period of a ULX binary.

Subsequently, we will propose to obtain spectroscopic observations to

obtain its radial velocity amplitude and thereby a dynamical estimate of

its mass.

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 28 28

SIGNIFICANT EVENTS: (None)