Daily Report #4257

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4257

PERIOD COVERED: UT December 11, 2006 (DOY 345)

OBSERVATIONS SCHEDULED

ACS/HRC 10878

An ACS Prism Snapshot Survey for z~2 Lyman Limit Systems

We propose to conduct a spectroscopic survey of Lyman limit absorbers
at redshifts 1.7 z 2.2, using ACS/HRC and the PR200L prism. We
have selected 100 quasars at 2.3 z 2.6 from the Sloan Digital Sky
Survey Spectroscopic Quasar sample, for which no BAL signature is
found at the QSO redshift and no strong metal absorption lines are
present at z 2.3 along the lines of sight. The survey has three main
observational goals. First, we will determine the redshift frequency
dN/dz of the LLS over the column density range 16.3 log N_HI 20.3
cm^-2. Second, we will measure the column density frequency
distribution f{N} for the partial Lyman limit systems {PLLS} over the
column density range 16.3 log N_HI 17.5 cm^-2. Third, we will
identify new sightlines for measurements of the primordial D/H ratio.
With this survey, we will also constrain two key quantities of
cosmological relevance: First, the measurements of dN/dz for optically
thick LLS and f{N} for the PLLS are critical to estimating the
attenuation of extragalactic ionizing sources {e.g. QSOs}. Currently,
uncertainties in dN/dz and f{N} are the greatest sources of
uncertainty for inferring the shape and intensity of the UV background
radiation field. Second, we will estimate the amount of metals in the
LLS using the f{N} and ground based observations of metal line
transitions. It is possible that a significant fraction of the
"missing metals" at z~2 are associated with these highly ionized
absorbers. Third, analysis of the LLS lends to investigations of the
interface between galaxies {i.e. the damped Lyman alpha systems} and
the intergalactic medium {i.e. the Lyman alpha forest}. This survey is
ideal for a snapshot observing program, because the on-object
integration times are less than 10 minutes, and the targets cover the
majority of the northern sky.

ACS/HRC 11041

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. For cycle 15 the program will cover 18
months 12.1.06-05.31.08 and it has been divied into three different
proposal each covering six months. The three proposals are
11041-11042-11043.

ACS/HRC/WFPC2/NIC3 10842

A Cepheid Distance to the Coma Cluster

We propose to use the Advanced Camera for Surveys to search for
Cepheid variables in two spiral galaxies in the core of the Coma
cluster. A direct application of the canonical primary distance
indicator at 100 Mpc will measure the far-field Hubble constant free
of many of the systematic uncertainties which beset current
determinations relying on secondary indicators. Establishing the
far-field H_o with Cepheids will provide one of the strongest links in
the extragalactic distance scale and will directly calibrate the
fiducial fundamental plane of elliptical galaxies in Coma. With
ACS/HRC, S/N=5 to 10 or better can be reached for Cepheids with
periods of 40d to 70d at mean light in 5 orbits with the F606W filter
if H_o=72 km/s/Mpc. Efficient detection and phasing can be done with
twelve epochs optimally spaced for periods of 40-70d.

ACS/WFC 10633

GRB afterglows and host galaxies at very high redshifts

Cosmology is beginning to constrain the nature of the earliest stars
and galaxies to form in the universe, but direct observation of
galaxies at z6 remains highly challenging due to their scarcity,
intrinsically small size, and high luminosity distance. GRB
afterglows, thanks to their extreme luminosities, offer the
possibility of circumventing these normal constraints by providing
redshifts and spectral information which couldn't be obtained by
direct observation of the hosts themselves. In addition, the
association of GRBs with massive stars means that they are a tracer of
star formation, and that their hosts are likely responsible for a
large proportion of the ionizing radiation during that era. Our
collaboration is mounting a campaign to rapidly identify and study
candidate very high redshift bursts, bringing to bear a network of 2,
4 and 8m telescopes with nIR instrumentation. The capabilities of
Swift to detect faint, distant GRBs, and to report accurate positions
for many bursts in near real-time makes our program now feasible. HST
is crucial to this endeavour, allowing us {a} to monitor the late time
afterglows and hence compare them to lower-z bursts and test the use
of GRBs as standard candles; and {b} characterise the basic
properties, luminosities, and in some cases morphologies, of the
hosts, which is essential to understanding these primordial galaxies
and their relationship to other populations.

ACS/WFC 10880

The host galaxies of QSO2s: AGN feeding and evolution at high
luminosities

Now that the presence of supermassive black holes in the nuclei of
galaxies is a well established fact, other questions related to the
AGN phenomena still have to be answered. Problems of particular
interest are how the AGN gets fed, how the black hole evolves and how
the evolution of the black hole is related to the evolution of the
galaxy bulge. Here we propose to address some of these issues using
ACS/WFC + F775W snapshot images of 73 QSO2s with redshifts in the
range 0.3z0.4. These observations will be combined with similar
archival data of QSO1s and ground based data of Seyfert and normal
galaxies. First, we will intestigate whether interactions are the most
important feeding mechanism in high luminosity AGNs. This will be done
in a quantitative way, comparing the asymmetry indices of QSO2 hosts
with those of lower luminosity AGNs and normal galaxies. Second, we
will do a detailed study of the morphology of the host galaxies of
both QSO types, to determine if they are similar, or if there is an
evolutionary trend from QSO2s to QSO1s. The results from this project
will represent an important step in the understanding of AGN
evolution, and may also introduce a substantial modification to the
Unified Model.

ACS/WFC 10917

Afterglows and Environments of Short-Hard Gamma-Ray Bursts

Discovery of the first afterglows of short-hard bursts {SHBs} has led
to a revolution in our understanding of these events, strongly
suggesting that they originate in the mergers of compact-object
binaries. Capitalizing on this progress, we propose to pursue the next
generation of SHB observations with HST, tracking the decay of all
accessible SHB afterglows to late times and pinpointing the location
of several more within the context of their host galaxies. These
observations will allow quantitative analysis of progenitor lifetimes
and short burst environments, enable direct confrontation with
population synthesis models, and provide updated event rate estimates
for the LIGO and VIRGO gravitational-wave detectors that are now
coming on-line.

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 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, 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.

WFPC2 10744

WFPC2 Cycle 14 Decontaminations and Associated Observations

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

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10555 - GSAcq(2,1,1) failed to RGA Hold (Gyro Control)

Upon acquisition of signal at 346/05:21:49, the GSAcq(2,1,1) scheduled
at 346/05:03:05 - 04:11:10 was observed to have failed to RGA Hold due
to search radius limit exceeded on FGS-1. One 486 ESB "a05" (FGS
Coarse Track failed - Search Radius Limit Exceeded) was received.
Pre-acquisition OBADs (RSS) attitude error corrections values not
available pending future ETR Dump due to LOS.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 05 04
FGS REacq 10 10
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)