Daily # 4272

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4272

PERIOD COVERED: UT January 04, 2007 (DOY 004)

OBSERVATIONS SCHEDULED

ACS/WFC 10798

Dark Halos and Substructure from Arcs & Einstein Rings

The surface brightness distribution of extended gravitationally lensed
arcs and Einstein rings contains super-resolved information about the
lensed object, and, more excitingly, about the smooth and clumpy mass
distribution of the lens galaxies. The source and lens information can
non-parametrically be separated, resulting in a direct "gravitational
image" of the inner mass- distribution of cosmologically-distant
galaxies {Koopmans 2005; Koopmans et al. 2006 [astro- ph/0601628]}.
With this goal in mind, we propose deep HST ACS-F555W/F814W and
NICMOS- F160W WFC imaging of 20 new gravitational-lens systems with
spatially resolved lensed sources, of the 35 new lens systems
discovered by the Sloan Lens ACS Survey {Bolton et al. 2005} so far,
15 of which are being imaged in Cycle-14. Each system has been
selected from the SDSS and confirmed in two time-efficient HST-ACS
snapshot programs {cycle 13&14}. High- fidelity multi-color HST images
are required {not delivered by the 420s snapshots} to isolate these
lensed images {properly cleaned, dithered and extinction-corrected}
from the lens galaxy surface brightness distribution, and apply our
"gravitational maging" technique. Our sample of 35 early-type lens
galaxies to date is by far the largest, still growing, and most
uniformly selected. This minimizes selection biases and small-number
statistics, compared to smaller, often serendipitously discovered,
samples. Moreover, using the WFC provides information on the field
around the lens, higher S/N and a better understood PSF, compared with
the HRC, and one retains high spatial resolution through drizzling.
The sample of galaxy mass distributions - determined through this
method from the arcs and Einstein ring HST images - will be studied
to: {i} measure the smooth mass distribution of the lens galaxies
{dark and luminous mass are separated using the HST images and the
stellar M/L values derived from a joint stellar-dynamical analysis of
each system}; {ii} quantify statistically and individually the
incidence of mass- substructure {with or without obvious luminous
counter-parts such as dwarf galaxies}. Since dark-matter substructure
could be more prevalent at higher redshift, both results provide a
direct test of this prediction of the CDM hierarchical
structure-formation model.

ACS/WFC 10918

Reducing Systematic Errors on the Hubble Constant: Metallicity
Calibration of the Cepheid PL Relation

Reducing the systematic errors on the Hubble constant is still of
significance and of immediate importance to modern cosmology. One of
the largest remaining uncertainties in the Cepheid- based distance
scale {which itself is at the foundation of the HST Key Project
determination of H_o} which can now be addressed directly by HST, is
the effect of metallicity on the Cepheid Period-Luminosity relation.
Three chemically distinct regions in M101 will be used to directly
measure and thereby calibrate the change in zero point of the Cepheid
PL relation over a range of metallicities that run from SMC-like,
through Solar, to metallicities as high as the most metal- enriched
galaxies in the pure Hubble flow. ACS for the first time offers the
opportunity to make a precise calibration of this effect which
currently accounts for at least a third of the total systematic
uncertainty on Ho. The calibration will be made in the V and I
bandpasses so as to be immediately and directly applicable to the
entire HST Cepheid-based distance scale sample, and most especially to
the highest-metallicity galaxies that were hosts to the Type Ia
supernovae, which were then used to extend the the distance scale
calibration out to cosmologically significant distances.

ACS/WFC/HRC 10920

High-Resolution Imaging of Nearby Lyman Break Galaxy Analogs in the
GALEX All-Sky Survey

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.
These compact UV luminous galaxies {UVLGs} resemble Lyman Break
Galaxies in terms of size, UV luminosity, star-formation rate, surface
brightness, mass, metallicity, kinematics, dust content, and color.
They have characteristic ``ages'' {stellar mass/SFR} of only a few
hundred Myr. This population of galaxies is thus worthy of study in
its own right and as a sample of local analogs of Lyman Break
Galaxies. We propose to image a sample of the 9 nearest and brightest
compact UVLGs in the near-ultraviolet, near-infrared, and H-alpha
using ACS. With these images we will 1} characterize their structure
and morphology, 2} look for signs of interactions and mergers, 3}
investigate the distribution and propogation of star formation over
varying time scales, and 4} quantify the stellar populations and star
formation history, in order to determine whether a previous generation
of stars formed long before the current burst. These data will
perfectly complement our existing Spitzer, GALEX, and SDSS data, and
will provide important information on star-formation in the
present-day universe as well as shed light on the earliest major
episodes of star formation in high-redshift galaxies.

ACS/WFC/WFPC2 10890

Morphologies of the Most Extreme High-Redshift Mid-IR-Luminous
Galaxies

The formative phase of the most massive galaxies may be extremely
luminous, characterized by intense star- and AGN-formation. Till now,
few such galaxies have been unambiguously identified at high redshift,
restricting us to the study of low-redshift ultraluminous infrared
galaxies as possible analogs. We have recently discovered a sample of
objects which may indeed represent this early phase in galaxy
formation, and are undertaking an extensive multiwavelength study of
this population. These objects are bright at mid-IR wavelengths
{F[24um]0.8mJy}, but deep ground based imaging suggests extremely
faint {and in some cases extended} optical counterparts {R~24-27}.
Deep K-band images show barely resolved galaxies. Mid-infrared
spectroscopy with Spitzer/IRS reveals that they have redshifts z ~
2-2.5, suggesting bolometric luminosities ~10^{13-14}Lsun! We propose
to obtain deep ACS F814W and NIC2 F160W images of these sources and
their environs in order to determine kpc-scale morphologies and
surface photometry for these galaxies. The proposed observations will
help us determine whether these extreme objects are merging systems,
massive obscured starbursts {with obscuration on kpc scales!} or very
reddened {locally obscured} AGN hosted by intrinsically low-luminosity
galaxies.

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 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 images. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

NIC2 10906

The Fundamental Plane of Massive Gas-Rich Mergers: II. The QUEST QSOs

We propose deep NICMOS H-band imaging of a carefully selected sample
of 23 local QSOs. This program is the last critical element of a
comprehensive investigation of the most luminous mergers in the nearby
universe, the ultraluminous infrared galaxies {ULIRGs} and the
quasars. This effort is called QUEST: Quasar / ULIRG Evolutionary
STudy. The high-resolution HST images of the QUEST QSOs will
complement an identical set of images on the ULIRG sample obtained
during Cycle 12, an extensive set of ground-based data that include
long-slit NIR spectra from a Large VLT Program, and a large set of
mid-infrared spectra from a Cycle 1 medium-size program with Spitzer.
This unique dataset will allow us to derive with unprecedented
precision structual, kinematic, and activity parameters for a large
unbiased sample of objects spanning the entire ULIRG/QSO luminosity
function. These data will refine the fundamental plane of massive
gas-rich mergers and enable us to answer the following quesitons: {1}
Do ultraluminous mergers form elliptical galaxies, and in particular,
giant ellipticals? {2} Do ULIRGs evolve into optical bright QSOs? The
results from this detailed study of massive mergers in the local
universe will be relevant to understanding the basic physical
processes involved in creating massive early-type host on the one
hand, and growing/feeding embedded massive black holes on the other,
in major galaxy mergers. This is an important question since 50% of
cosmic star formation at high-z and most of the big BHs appear to be
formed in this process.

NIC2, ACS/WFC 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting
in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at
redshifts exceeding 1 are now the leading obstacles to determining the
nature of dark energy. We propose a single, integrated set of
observations for Cycle 15 that will provide a 40% improvement in
constraints on dark energy. This program will observe known Cepheids
in six reliable hosts of Type Ia supernovae with NICMOS, reducing the
uncertainty in H_0 by a factor of two because of the smaller
dispersion along the instability strip, the diminished extinction, and
the weaker metallicity dependence in the infrared. In parallel with
ACS, at the same time the NICMOS observations are underway, we will
discover and follow a sample of Type Ia supernovae at z 1. Together,
these measurements, along with prior constraints from WMAP, will
provide a great improvement in HST's ability to distinguish between a
static, cosmological constant and dynamical dark energy. The Hubble
Space Telescope is the only instrument in the world that can make
these IR measurements of Cepheids beyond the Local Group, and it is
the only telescope in the world that can be used to find and follow
supernovae at z 1. Our program exploits both of these unique
capabilities of HST to learn more about one of the greatest mysteries
in science.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

10595 - GSAcq(2,1,2) failed due to Scan Step limit exceeded on FGS 2

Upon acquisition at 004/16:01:30z the GSAcq (2,1,2) scheduled at
004/15:52:00 failed due to scan step limit exceeded. Previous OBAD RSS
was 17.26 a/s Post acq MAP RSS was 13.85 a/s

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 10 09
FGS REacq 05 05
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)