Daily # 4236

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4236

PERIOD COVERED: UT November 07, 2006 (DOY 311)

OBSERVATIONS SCHEDULED

ACS/HRC 10832

Solving the microlensing puzzle: An HST high-resolution imaging
approach

We propose to use the HST Advanced Camera for Surveys High Resolution
Channel to obtain high resolution imaging data for 10 bona-fide LMC
microlensing events seen in the original MACHO survey. The purpose of
this survey will be to assess whether or not the lens and source stars
have separated enough to be resolved since the original microlensing
event took place - about a decade has passed since the original MACHO
survey and the HST WFPC2 follow-up observations of the microlensing
events. If the components of the lensing event are resolved, we will
determine the apparent magnitude and color of both the lens and the
source stars. These data, in combination with Spitzer/IRAC data and
Magellan near-IR JHK data, will be used to ascertain the basic
properties of the lens stars. With the majority of the microlensing
events in the original MACHO survey observed at the highest spatial
resolution currently possible, we will be able to draw important
conclusions as to what fraction of these events have lenses which
belong to some population of dwarf stars in the disk and what fraction
must be due to lenses in the halo or beyond. These data will greatly
increase our understanding of the structure of the Galaxy by
characterizing the stellar population responsible for the
gravitational microlensing.

ACS/HRC/WFC 10733

CCD Hot Pixel Annealing

Hot pixel annealing will continue to be performed once every 4 weeks.
The CCD TECs will be turned off and heaters will be activated to bring
the detector temperatures to about +20C. This state will be held for
approximately 6 hours, after which the heaters are turned off, the
TECs turned on, and the CCDs returned to normal operating condition.
To assess the effectiveness of the annealing, a bias and four dark
images will be taken before and after the annealing procedure for both
WFC and HRC. The HRC darks are taken in parallel with the WFC darks.
The charge transfer efficiency {CTE} of the ACS CCD detectors declines
as damage due to on-orbit radiation exposure accumulates. This
degradation has been closely monitored at regular intervals, because
it is likely to determine the useful lifetime of the CCDs. We combine
the annealling activity with the charge transfer efficiency monitoring
and also merge into the routine dark image collection. To this end,
the CTE monitoring exposures have been moved into this proposal . All
the data for this program is acquired using internal targets {lamps}
only, so all of the exposures should be taken during Earth occultation
time {but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

ACS/WFC 10793

A Survey for Supernovae in Massive High-Redshift Clusters

We propose to continue our ongoing program designed to measure, to an
unprecedented 30% accuracy, the SN-Ia rate in a sample of massive
z=0.5-0.9 galaxy clusters. The SN-Ia rate is a poorly known
observable, especially at high z, and in cluster environments. The SN
rate and its redshift dependence can serve as powerful discrimiminants
for a number of key issues in astrophysics and cosmology. Our
observations will: 1. Put clear constraints on the characteristic
SN-Ia "delay time," the typical time between the formation of a
stellar population and the explosion of some of its members as SNe-Ia.
Such constraints can exclude entire categories of SN-Ia progenitor
models, since different models predict different delays. 2. Help
resolve the question of the dominant source of the high metallicity in
the intracluster medium {ICM} - SNe-Ia, or core-collapse SNe from an
early stellar population with a top-heavy IMF, perhaps those
population III stars responsible for the early re-ionization of the
Universe. Since clusters are excellent laboratories for studying
enrichment {they generally have a simple star-formation history, and
matter cannot leave their deep potentials}, the results will be
relevant for understanding metal enrichment in general, and the
possible role of first generation stars in early Universal enrichment.
Observations obtained so far during cycle 14 yield many SNe in our
cluster fields, but our follow-up campaign reveals most are not in
cluster galaxies. Our interim results indicate a cluster SN rate at
the very low end of the range considered, and its accuracy is limited
by the small number of cluster SNe. We request additional visits to
increase the number of cluster SNe and achieve a measurement that is
not limited by Poisson errors. A detailed progress report is included.

ACS/WFC 10881

The Ultimate Gravitational Lensing Survey of Cluster Mass and
Substructure

We propose a systematic and detailed investigation of the mass,
substructure, and thermodynamics of one hundred X-ray luminous galaxy
clusters at 0.15z0.3. The primary goal is to test our recent
suggestion that this population is dominated by dynamically immature
disturbed clusters, and that the observed mass-temperature relation
suffers strong structural segregation. If confirmed, this would
represent a paradigm shift in our observational understanding of
clusters, that were hitherto believed to be dominated by mature,
undisturbed systems. The key observation to this endeavor is Hubble
imaging of cluster cores to identify robustly tangential and radial
multiple arcs and measure the shape of faint galaxies. These strong
and weak lensing signals will give an accurate measure of the total
mass and structure of the dark matter distribution that we will
subsequently compare with X-ray and Sunyaev Zeldovich Effect
observables. The broader applications of our project include 1} the
calibration of mass-temperature and mass-SZE scaling relations which
will be critical for the calibration of proposed dark energy
experiments, and 2} the low redshift baseline study of the
demographics of massive clusters to aid interpretation of future high
redshift {z1} cluster samples. For this ultimate cluster survey, we
request ACS SNAPSHOTS through the F606W filter drawn from a target
list of 143 clusters.

ACS/WFC/NIC2 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with
Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful
"dust free" Type Ia supernovae {SNe Ia} dataset than available with
the previous GOODS searches. Moreover, this approach provides a
strikingly more efficient search-and-follow-up that is primarily pre-
scheduled. The resulting dark energy measurements do not share the
major systematic uncertainty at these redshifts, that of the
extinction correction with a prior. By targeting massive galaxy
clusters at z 1 we obtain a five-times higher efficiency in
detection of Type Ia supernovae in ellipticals, providing a
well-understood host galaxy environment. These same deep cluster
images then also yield fundamental calibrations required for future
weak lensing and Sunyaev-Zel'dovich measurements of dark energy, as
well as an entire program of cluster studies. The data will make
possible a factor of two improvement on supernova constraints on dark
energy time variation, and much larger improvement in systematic
uncertainty. They will provide both a cluster dataset and a SN Ia
dataset that will be a longstanding scientific resource.

ACS/WFC/WFPC2 10820

Galaxy properties in a Filament in Abell 851

We propose to image two fields that cover the filament of galaxies
that is streaming into the remarkable cluster Abell 851, z=0.41, one
of the two examples of the expected mechanism of cluster growth. These
observations will test theories of alteration of galaxy morphology and
star formation history for galaxies infalling into intermediate
redshift clusters.

FGS 10929

Calibrating the Mass-Luminosity Relation at the End of the Main
Sequence

We propose to use HST-FGS1R to finish calibrating the mass-luminosity
relation for stars less massive than 0.5 Msun, with special emphasis
on objects near the stellar/substellar border. Our goals are to
determine Mv values to 0.05 magnitude and masses to 5%, and thereby
build the fundamental database of stellar masses that we will use to
test theoretical models as never before. This program uses the
combination of HST-FGS3/FGS1R at optical wavelengths, historical
infrared speckle data, ground-based parallax work, metallicity
studies, and radial velocity monitoring to examine nearby,
subarcsecond binary systems. The high precision separation and
position angle measurements with HST-FGS3/FGS1R {to 1 mas in the
separations} for these faint {V = 10-15} targets simply cannot be
equaled by any ground-based technique. As a result of these
measurements, we are deriving high quality luminosities and masses for
the components in the systems, and characterizing their spectral
energy distributions from 0.5 to 2.2 microns. One of the objects, GJ
1245 C with mass 0.074 +/- 0.002 Msun, is the only object known with
an accurate dynamical mass less than 0.10 Msun. The payoff of this
proposal is high because the six systems selected for final
observations in Cycles 15 and 16 have already been resolved during
Cycles 5-13 with HST FGS3/FGS1R and contain most of the reddest
objects for which accurate dynamical masses can be determined.

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 10893

Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble
Diagram

We propose building a high-z Hubble Diagram using type Ia supernovae
observed in the infrared rest-frame J-band. The infrared has a number
of exceptional properties. The effect of dust extinction is minimal,
reducing a major systematic tha may be biasing dark energy
measurements. Also, recent work indicates that type Ia supernovae are
true standard candles in the infrared meaning that our Hubble diagram
will be resistant to possible evolution in the Phillips relation over
cosmic time. High signal-to-noise measurements of 9 type Ia events at
z~0.4 will be compared with an independent optical Hubble diagram from
the ESSENCE project to test for a shift in the derived dark energy
equation of state due to a systematic bias. Because of the bright sky
background, H-band photometry of z~0.4 supernovae is not feasible from
the ground. Only the superb image quality and dark infrared sky seen
by HST makes this test possible. This experiment may also lead to a
better, more reliable way of mapping the expansion history of the
universe with the Joint Dark Energy Mission.

NIC3/NIC1/NIC2 11059

Flats Stability

This calibration proposal is the Cycle 15 NICMOS flat field monitor
program. A series of camera 1, 2, & 3 flat fields will be obtained to
monitor the health of the cameras.

WFPC2 10745

WFPC2 CYCLE 14 INTERNAL MONITOR

This calibration proposal is the Cycle 14 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{both gain 7 and gain 15 -- to test stability of gains and bias
levels}, a test for quantum efficiency in the CCDs, and a monitor for
possible buildup of contaminants on the CCD windows. These also
provide raw data for generating annual super-bias reference files for
the calibration pipeline.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10498 - GSACQ (2,3,3) failed, Search Radius Limit Exceeded on FGS 3

GSACQ(2,3,3) at 311/18:09:17 failed due to Search Radius Limit
Exceeded on FGS 3 at 18:13:25. OBAD data prior to GSACQ showed RSS
attitude correction of 9.68 arcseconds, OBAD map after GSACQ failure
showed RSS error of 27.90 arcseconds.

COMPLETED OPS REQUEST:
17956-0 - GenSlew for Proposal 10847 - Slot 12
17957-0 - GenSlew for Proposal 10847 - Slot 13
17958-0 - GenSlew for Proposal 10847 - Slot 14
17959-0 - GenSlew for Proposal 10847 - Slot 01

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 09 08
FGS REacq 05 05
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)