Daily # 4258

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4258

PERIOD COVERED: UT December 12, 2006 (DOY 346)

OBSERVATIONS SCHEDULED

ACS/HRC 10877

A Snapshot Survey of the Sites of Recent, Nearby Supernovae

During the past few years, robotic {or nearly robotic} searches for
supernovae {SNe}, most notably our Lick Observatory Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite nearby
galaxies {cz 4000 km/s}. Most of the objects were discovered before
maximum brightness, and have follow-up photometry and spectroscopy;
they include some of the best-studied SNe to date. We propose to
conduct a snapshot imaging survey of the sites of some of these nearby
objects, to obtain late-time photometry that {through the shape of the
light and color curves} will help reveal the origin of their lingering
energy. The images will also provide high-resolution information on
the local environments of SNe that are far superior to what we can
procure from the ground. For example, we will obtain color-color and
color-magnitude diagrams of stars in these SN sites, to determine the
SN progenitor masses and constraints on the reddening. Recovery of the
SNe in the new HST images will also allow us to actually pinpoint
their progenitor stars in cases where pre- explosion images exist in
the HST archive. This proposal is an extension of our successful Cycle
13 snapshot survey with ACS. It is complementary to our Cycle 15
archival proposal, which is a continuation of our long-standing
program to use existing HST images to glean information about SN
environments.

ACS/HRC 11051

CCD Stability Monitor

This program will verify that the low frequency flat fielding, the
photometry, and the geometric distortion are stable in time and across
the field of view of the CCD arrays.

ACS/HRC 11053

Earth Flats

Sky flats will be obtained by observing the bright Earth with the HRC
and WFC. These observations will be used to verify the accuracy of the
latest pipeline flats and to monitor any changes. Weekly coronagraphic
monitoring is required to assess the changing position of the spots.

ACS/SBC 11049

SBC Darks

This takes a series of SBC dark measurements over a continuous period
of about 6 hours {4 orbits}. The aim is to collect dark images during
an extended SBC on-time. Earlier measuremrents indicate that the dark
current increases with SBC on-time and may also be increasing with
overall SBC use. The 6-hour time matches the longest time used by any
observer. As with all SBC observations this needs continuous SAA free
time. Since no other ACS observation can be taken in parallel with the
SBC, it is an aim to schedule this in parallel with a NICMOS or WFPC2
observations

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 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 10886

The Sloan Lens ACS Survey: Towards 100 New Strong Lenses

As a continuation of the highly successful Sloan Lens ACS {SLACS}
Survey for new strong gravitational lenses, we propose one orbit of
ACS-WFC F814W imaging for each of 50 high- probability strong
galaxy-galaxy lens candidates. These observations will confirm new
lens systems and permit immediate and accurate photometry, shape
measurement, and mass modeling of the lens galaxies. The lenses
delivered by the SLACS Survey all show extended source structure,
furnishing more constraints on the projected lens potential than
lensed-quasar image positions. In addition, SLACS lenses have lens
galaxies that are much brighter than their lensed sources,
facilitating detailed photometric and dynamical observation of the
former. When confirmed lenses from this proposal are combined with
lenses discovered by SLACS in Cycles 13 and 14, we expect the final
SLACS lens sample to number 80--100: an approximate doubling of the
number of known galaxy-scale strong gravitational lenses and an
order-of-magnitude increase in the number of optical Einstein rings.
By virtue of its homogeneous selection and sheer size, the SLACS
sample will allow an unprecedented exploration of the mass structure
of the early-type galaxy population as a function of all other
observable quantities. This new sample will be a valuable resource to
the astronomical community by enabling qualitatively new strong
lensing science, and as such we will waive all but a short {3-month}
proprietary period on the observations.

ACS/WFC 10905

The Dynamic State of the Dwarf Galaxy Rich Canes Venatici I Region

With accurate distances, the nearest groups of galaxies can be
resolved in 3 dimensions and the radial component of the motions of
galaxies due to local density perturbations can be distinquished from
cosmological expansion components. Currently, with the ACS, galaxy
distances within 8 Mpc can be measured effectively and efficiently by
detecting the tip of the red giant branch {TRGB}. Of four principal
groups at high galactic latitude in this domain, the Canes Venatici I
Group {a} is the least studied, {b} is the most populated, though
overwhelmingly by dwarf galaxies, and {c} is likely the least
dynamically evolved. It is speculated that galaxies in low mass groups
may fail to retain baryons as effectively as those in high mass
groups, resulting in significantly higher mass-to-light ratios. The
CVn I Group is suspected to lie in the mass regime where the
speculated astrophysical processes that affect baryon retention are
becoming important.

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: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 08 08
FGS REacq 07 07
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)