Daily # 4182

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4182

PERIOD COVERED: UT August 21, 2006 (DOY 233)

OBSERVATIONS SCHEDULED

ACS/HRC/WFC 10575

Lyman alpha morphology of local starburst galaxies

Our pilot imaging study of 6 local galaxies using ACS/SBC in the
cosmologically important Lyman- alpha line has begun to reveal
intriguing results. Here we propse ACS/HRC imaging of this sample, the
approval of the which will allow for a significant increase in the
impact of the original study and extend the limits of current
understanding of Lyman-alpha escape. With this data we can accurately
calibrate our Lyman-alpha line-only images and explore for the first
time Lyman- alpha fluxes and equivalent widths in spatially resolved
systems. These data would also allow us to test the current models of
Lyman-alpha escape mechanisms and investigate possible correlations
between Lyman-alpha emission and other local parameters such as age
and internal reddening. The addition of high-resolution H-alpha data
allows us to quantitatively study the decoupling of Lyman-alpha from
non-resonant radiation and spatially explore the destruction and
attenuation of Lyman-alpha. The study will go a long way towards
resolving the outstanding issues complicating the interpretation of
high redshift studies and the use of Lyman-alpha to quantitatively
study the distant universe.

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.

ACS/SBC 10554

Globular Cluster Systems of Elliptical Galaxies in Low Density
Environments

We propose to use the ACS/WFC to determine colour {metallicity}
distributions and luminosity functions for the globular cluster
populations in a well-defined sample of elliptical galaxies in low-
density environments, and to compare the results with similar samples
taken from a rich cluster environment. Low-luminosity ellipticals are
now recognized to play a pivotal role in testing hierarchical models
of galaxy formation, and their globular cluster populations provide a
unique probe of their star formation and metal enrichment history. The
data will be used to {i} determine whether the bimodal colour
distributions indicative of multiple formation epochs in luminous
ellipticals are also prevalent in low-luminosity field ellipticals;
{ii} place joint constraints on age and metallicity in systems with
more than one population and determine the spread of ages in any one
system; {iii} test whether cluster destruction processes {e.g. tidal
shocking} are more effective in low-luminosity ellipticals, as
predicted from their higher mass densities. ACS observations are
essential to eliminate foreground/background contamination and to
probe deep into the luminosity function to obtain a good statistical
sample of clusters. The TAC has previously awarded HST time to two
large surveys of globular cluster systems in rich cluster
environments, but there is currently no comparable survey in
low-density environments with which to compare these results.

ACS/SBC 10739

Internal Flat Field Stability

The stability of the CCD flat fields will be monitored using the
calibration lamps and a sub-sample of the filter set. For the SBC
imaging filters, differences in the low-frequency flat field structure
with wavelength will be assessed. New high signal P-flats will be
obtained for the SBC prisms.

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.

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.

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.

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.

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 07 07
FGS REacq 08 08
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)