Daily # 4186

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4186

PERIOD COVERED: UT August 25,26,27, 2006 (DOY 237,238,239)

OBSERVATIONS SCHEDULED

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.

FGS 10912

Trigonometric Calibration of the Distance Scale for Classical Novae

The distance scale for classical novae is important for understanding
the stellar physics of their thermonuclear runaways, their
contribution to Galactic nucleosynthesis, and their use as
extragalactic standard candles. Although it is known that there is a
relationship between their absolute magnitudes at maximum light and
their subsequent rates of decline--the well-known maximum-magnitude
rate-of-decline {MMRD} relation--it is difficult to set the zero-point
for the MMRD because of the very uncertain distances of Galactic
novae. We propose to measure precise trigonometric parallaxes for the
quiescent remnants of the four nearest classical novae. We will use
the Fine Guidance Sensors, which are proven to be capable of measuring
parallaxes with errors of ~0.2 mas, well below what is possible from
the ground.

ACS/HRC 10909

Exploring the diversity of cosmic explosions: The supernovae of
gamma-ray bursts

While the connection between gamma-ray bursts {GRBs} and supernovae
{SNe} is now clearly established, there is a large variety of
observational properties among these SNe and the physical parameters
of these explosions are poorly known. As part of a comprehensive
program, we propose to use HST in order to obtain basic information
about the supernovae associated with gamma-ray bursts. HST offers the
means to cleanly separate the light curves of the GRB afterglow from
the supernova, and to remove the contamination from the host galaxy,
opening a clear route to the fundamental parameters of the SN. From
these observations, we will determine the absolute magnitude at
maximum, the shape of the spectral energy distribution, and any change
over time of the energy distribution. We will also measure the rate of
decay of the exponential tail. Merged with the ground-based data that
we will obtain for each event, we will be able to compare our data set
to models and constrain the energy of the explosion, the mass of the
ejecta and the mass of Nickel synthesized during the explosion. These
results will shed light on the apparent variety of supernovae
associated with gamma-ray bursts and X-ray flashes, and on the
relation between these SNe and other, more common varieties of core-
collapse explosions.

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.

ACS/HRC 10870

The Ring Plane Crossings of Uranus in 2007

The rings of Uranus turn edge-on to Earth in May and August 2007. In
between, we will have a rare opportunity to see the unlit face of the
rings. With the nine optically thick rings essentialy invisible, we
will observe features and phenomena that are normally lost in their
glare. We will use this opportunity to search thoroughly for the
embedded "shepherd" moons long believed to confine the edges of the
rings, setting a mass limit roughly 10 times smaller than that of the
smallest shepherd currently known, Cordelia. We will measure the
vertical thicknesses of the rings and study the faint dust belts only
known to exist from a single Voyager image. We will also study the
colors of the newly-discovered faint, outer rings; recent evidence
suggests that one ring is red and the other blue, implying that each
ring is dominated by a different set of physical processes. We will
employ near-edge-on photometry from 2006 and 2007 to derive the
particle filling factor within the rings, to observe how ring epsilon
responds to the "traffic jam" as particles pass through its narrowest
point, and to test the latest models for preserving eccentricities and
apse alignment within the rings. Moreover, this data set will allow us
to continue monitoring the motions of the inner moons, which have been
found to show possibly chaotic orbital variations; by nearly doubling
the time span of the existing ACS astrometry, the details of the
variations will become much clearer.

NIC3 10839

The NICMOS Polarimetric Calibration

Recently, it has been shown that NICMOS possesses an instrumental
polarization at a level of 1.2%. This completely inhibits the data
reduction in a number of previous GO programs, and hampers the ability
of the instrument to perform high accuracy polarimetry. In all, 90
orbits of HST data are affected, with potentially many more in Cycle
15. We propose to obtain high signal to noise observations of three
polarimetric standards at the cardinal roll angles of the NICMOS
polarizers for both NIC1 and NIC2. These observations are designed to
fully characterize the instrumental polarization in order for NICMOS
to reach its full potential by enabling high accuracy polarimetry of
sources with polarizations around 1%. The residual polarization will
also be determined as a function of position and spectral energy
distribution. Our group will rapidly turn around the required data
products and produce reports and software for the accurate
representation of the instrumental polarization. These items will be
presented to STScI and for dissemination among the wider astronomical
community.

ACS/WFC 10816

The Formation History of Andromeda's Extended Metal-Poor Halo

We propose deep ACS imaging in the outer spheroid of the Andromeda
galaxy, in order to measure the star formation history of its true
halo. For the past 20 years, nearly all studies of the Andromeda
"halo" were focused on the spheroid within 30 kpc of the galaxy's
center, a region now known to host significant substructure and
populations with high metallicity and intermediate ages. However, two
groups have recently discovered an extended metal-poor halo beyond 30
kpc; this population is distinct in its surface-brightness profile,
abundance distribution, and kinematics. In earlier cycles, we obtained
deep images of the inner spheroid {11 kpc on the minor axis}, outer
disk {25 kpc on the major axis}, and giant tidal stream, yielding the
complete star formation history in each field. We now propose deep ACS
imaging of 4 fields bracketing this 30 kpc transition point in the
spheroid, so that the inner spheroid and the extended halo populations
can be disentangled, enabling a reconstruction of the star formation
history in the halo. A wide age distribution in the halo, as found in
the inner spheroid, would imply the halo was assembled through ongoing
accretion of satellite galaxies, while a uniformly old population
would be a strong indication that the halo was formed during the early
rapid collapse of the Andromeda proto-galaxy.

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.

ACS/WFC 10760

Black Hole X-ray Novae in M31

We have been carring out a Chandra {GO+GTO} and HST {GO} program to
find Black Hole X-ray Nova {BHXN} and their optical counterparts in
M31 for several years. To date we have found 2 dozen BHXN and 3 HST
optical counterparts for these BHXN. Our results suggest a rather high
ratio of BH to neutron star {NS} binaries, or a high duty cycle for
the BHXN. We propose to continue this program, with the goal of
determining the orbital period distribution and duty cycles of these
BHXN. Current results yield 3 orbital periods and 2 upper limits. Our
proposed observations will ~double the total number of periods and
therefore yield sufficient numbers to make a first approximation of
the orbital period distribution. The orbital period distribution is
the fundamental observable parameter any binary stellar evolution
models must match, and the duty cycle is very poorly known but
directly influences the binary lifetime. M31 is the only galaxy in
which this extra-galactic study of BHXN is feasible.

ACS/HRC/WFC 10758

ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This programme will be
for the entire lifetime of ACS. Changes from cycle 13:- The default
gain for WFC is 2 e-/DN. As before bias frames will be collected for
both gain 1 and gain 2. Dark frames are acquired using the default
gain {2}. This program cover the period May, 31 2006- Oct, 1-2006. The
first half of the program has a different proposal number: 10729.

WFPC2 10744

WFPC2 Cycle 14 Decontaminations and Associated Observations

This proposal is for the WFPC2 decons. Also included are instrument
monitors tied to decons: photometric stability check, focus monitor,
pre- and post-decon internals {bias, intflats, kspots, & darks}, UV
throughput check, VISFLAT sweep, and internal UV flat check.

WFPC2 10631

Intermediate-Age Globular Clusters in M31

We propose deep ACS/WFC imaging of four halo M31 globular clusters in
order to derive their horizontal branch morphologies. Our
spectroscopic investigation of their integrated light identifies them
as members of an intermediate-age population of globular clusters in
M31. Since our spectroscopic results are based on the analysis of
Balmer absorption lines, we need to secure our results against an
artificial juvenation due to extreme horizontal branch morphologies.
The proposed observations will allow a clear-cut answer to the
question of whether spectroscopically derived intermediate-age
estimates are due to genuinely younger ages or are the result of
anomalously hot horizontal branch morphologies. Either way, our
results will have important implications for spectroscopically derived
ages and metallicities of distant stellar populations. Because of the
high spatial resolution of the proposed ACS/WFC observations we will
also derive accurate surface brightness profiles of our target
globular clusters and investigate the influence of stellar density on
horizontal branch morphology. Moreover, together with deep parallel
WFPC2 fields we will study the metallicity dispersion of the
background stellar population in M31 as a function of galactocentric
radius.

NIC3/ACS/WFC 10504

Characterizing the Sources Responsible for Cosmic Reionization

Our group has demonstrated the role that massive clusters, acting as
powerful cosmic lenses, can play in constraining the abundance and
properties of low-luminosity star-forming sources beyond z~6; such
sources are thought to be responsible for ending cosmic reionization.
The large magnification possible in the critical regions of
well-constrained clusters brings sources into view that lie at or
beyond the limits of conventional exposures such as the UDF, as well
as those in imaging surveys being undertaken with IRAC onboard
Spitzer. We have shown that the combination of HST and Spitzer is
particularly effective in delivering the physical properties of these
distant sources, constraining their mass, age and past star formation
history. Indirectly, we therefore gain a valuable glimpse to yet
earlier epochs. Recognizing the result {and limitations} of the UDF
exposure, we propose a systematic search through 6 lensing clusters
with ACS and NICMOS for further z~6-7 sources in conjunction with
existing deep IRAC data. Our survey will mitigate cosmic variance and
extend the search both to lower luminosities and, by virtue of the
NICMOS/IRAC combination, to higher redshift. The goal is to count and
characterize representative sources at z~6-10 and to delineate the
redshift range of activity for the planning of future observations.

ACS/WFC 10258

Tracing the Emergence of the Hubble Sequence Among the Most Luminous
and Massive Galaxies

There is mounting evidence that the redshift range 1 z 2 was an
important era when massive galaxies assembled their stellar content
and assumed their present--day morphologies. Despite extensive HST
imaging surveys, however, there is very little data in the optical
rest frame {i.e., observed near--infrared} on the morphologies of the
most luminous galaxies at these redshifts. We propose to image a
carefully selected set of 20 of the most luminous, K--band selected
GOODS galaxies at 1.3 z 2, using NICMOS camera 2. This offers
diffraction--limited, critically sampled imaging at 1.6 microns to
ensure the best angular resolution for comparison to ACS. The galaxies
are chosen to span a simple 4--fold parameter space of morphological
and spectral type, in order to provide the most information about the
variety of massive galaxy properties in this redshift range. We will
investigate the emergence of large scale--length disks, stable spiral
structure, mature bulges with red stellar populations, central bar
structures, the incidence of disturbed morphology, the existence {or
lack thereof} of blue ellipticals, and other questions that concern
the evolution and maturation of the brightest, largest, and most
massive ordinary galaxies in this critical redshift range.

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:
17898-0 - Battery 4 Capacity Test Script & 5 Battery Pressure
Limit COP @ 237/1335z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 20 20
FGS REacq 24 24
OBAD with Maneuver 86 86

SIGNIFICANT EVENTS:

Battery 4 Capacity Test Final Flash Report

At approximately 2006/237 13:26 GMT (9:26 am local), Battery 4 was
successfully commanded back on-line in FSW. The remaining commanding
of the Battery 4 Reconditioning script was completed at approximately
2006/237 13:42 GMT (9:42 am local). EPS SEs monitored the system for 4
orbits after restoring EPS to a 6-battery FSW configuration and
observed that the FSW SOC vs pressure-based SOC variance is 15 AH.
Nominal system performance was observed for the rest of the EPS
system. Battery temperatures are still cycling below 1.0 DegC. This
concludes the 2006 Battery Capacity Test season