Daily Report # 4319

Notice: For the foreseeable future, the daily reports may contain
apparent discrepancies between some proposal descriptions and the listed
instrument usage. This is due to the conversion of previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS observations
subsequent to the loss of ACS CCD science capability in late January.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4319

PERIOD COVERED: UT March 14, 2007 (DOY 073)

OBSERVATIONS SCHEDULED

FGS 10801

Direct Determination of Kuiper Belt Object Diameters with HST

When it comes to fundamental properties of an astronomical object, it
is difficult to think of a more fundamental physical property than its
size. Because of their distance, objects in the Kuiper Belt are
generally too small for their disks to be resolved. The heterogeneous
albedo and color of the Kuiper Belt population makes size estimates
from observed absolute magnitude highly uncertain. And the
long-awaited data from the Spitzer Space Telescope suffers from our
ignorance of crucial macro- and micro-physical properties such as spin
period, pole orientation, surface roughness, and thermal inertia. We
propose to add a new dimension to the measurement of KBO diameters by
employing two techniques that will directly measure the diameters of
three large KBOs. We expect to obtain diameter measurements with
uncertainties of 10% or better and utilize these to validate and cross
calibrate the growing web of diameter measurements for KBOs.

NIC2 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.

FGS 10989

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric
elements {perturbation orbit semi-major axis and inclination} of
extra-solar planets orbiting six stars. These companions were
originally detected by radial velocity techniques. We have
demonstrated that FGS astrometry of even a short segment of reflex
motion, when combined with extensive radial velocity information, can
yield useful inclination information {McArthur et al. 2004}, allowing
us to determine companion masses. Extrasolar planet masses assist in
two ongoing research frontiers. First, they provide useful boundary
conditions for models of planetary formation and evolution of
planetary systems. Second, knowing that a star in fact has a plantary
mass companion, increases the value of that system to future
extrasolar planet observation missions such as SIM PlanetQuest, TPF,
and GAIA.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

A new proceedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and everytime 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 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.

NIC3 11080

Exploring the Scaling Laws of Star Formation

As a variety of surveys of the local and distant Universe are
approaching a full census of galaxy populations, our attention needs
to turn towards understanding and quantifying the physical mechanisms
that trigger and regulate the large-scale star formation rates {SFRs}
in galaxies.

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.

WFPC2 11084

Probing the Least Luminous Galaxies in the Local Universe

We propose to obtain deep color-magnitude data of eight new Local
Group galaxies which we recently discovered: Andromeda XI, Andromeda
XII, and Andromeda XIII {satellites of M31}; Canes Venatici I, Canes
Venatici II, Hercules, and Leo IV {satellites of the Milky Way}; and
Leo T, a new "free-floating" Local Group dwarf spheroidal with
evidence for recent star formation and associated H I gas. These
represent the least luminous galaxies known at *any* redshift, and are
the only accessible laboratories for studying this extreme regime of
galaxy formation. With deep WFPC-2 F606W and F814W pointings at their
centers, we will determine whether these objects contain single or
multiple age stellar populations, as well as whether these objects
display a range of metallicities.


FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10739 - GSAcq (1,2,1) failed due to QSTOP Flag on FGS

GSAcq (1,2,1) at 074/02:12:05-02:19:22 failed due to QSTOP & QF1STOPF
flaggs on FGS 1. Received no 486 ESB messages.
OBAD #1 RSS: 3424.76
OBAD #2 RSS: 16.98
OBAD MAP RSS: 2.37

10740 - ACS 779 Fold Mechanism Move was Blocked

At 074/02:20:24 Received Status Buffer Message ACS 779 (x2) (Fold
Mechanism Move Was Blocked) #1 P=0, T= 30057, #2 P=0, T=35017. This
was the result of the failed GSAcq at 02:14:58 so the TDF was down
when the fold mechanism move to the SBC position was commanded. The
move is blocked and SBC MAMA HV will remain on. The MAMA HV staying on
is a new feature for ACS FSW CS4.01


COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 09 08
FGS REacq 06 06
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)