DAILY REPORT #3901

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT #3901

PERIOD COVERED: UT July 13, 2005 (DOY 194)

OBSERVATIONS SCHEDULED

ACS/HRC 10623

HST Optical Snapshot Survey of Intermediate Redshift Ultraluminous
Infrared Galaxies

Ultraluminous infrared galaxies {ULIGs} are commonly believed to be a
transitory phase in the evolution of disk galaxy mergers into QSOs.
However, a recently reported discrepancy between the morphological and
structural properties of z 0.13 ULIGs and z = 0.12-0.25 QSOs with
M{V} -23.5 has cast doubt on their evolutionary connection. We
propose an ACS snapshot survey of a sample of 39 ULIGs with z =
0.35-1.0. These galaxies are the best suited for comparison with
luminous z=0.12-0.25 QSOs because {1} they are at larger lookback
times than local ULIGs, and thus are likely representative of the
systems that evolve into lower redshift luminous QSOs, {2} they have
luminosities comparable to luminous QSOs and, {3} they are selected in
a manner that biases the sample towards harboring imbedded AGN, and
thus are the most likely precursors to optical QSOs. High resolution
HST ACS images will allow a determination of galaxy morphology and
reveal the presence of bright AGN. The 2-D profile of each galaxy will
be modeled using GALFIT, with the AGN comprising one component of the
fit where applicable to better characterize the underlying galaxy.
Fundamental parameters {effective radius and surface brightness, and
F814W-band magnitude} of the underlying galaxy will thus be measured
and compared with the host galaxies of the luminous QSO sample. This
imaging campaign will consume a modest amount of HST time, but will
provide for the first time a statistically significant view of ULIGs
at look-back times of 30-65% the age of the universe, and sufficient
resolution and sensitivity to conduct a meaningful comparison with
z=0.12-0.25 QSOs, as well as with local {z 0.3} IRAS- detected and
distant {z 2} SCUBA-detected ULIGs.

ACS/HRC/NIC3 10182

Towards a Comprehensive Understanding of Type Ia Supernovae: The
Necessity of UV Observations

Type Ia supernovae {SNe Ia} are very important to many diverse areas
of astrophysics, from the chemical evolution of galaxies to
observational cosmology which led to the discovery of dark energy and
the accelerating Universe. However, the utility of SNe Ia as
cosmological probes depends on the degree of our understanding of SN
Ia physics, and various systematic effects such as cosmic chemical
evolution. At present, the progenitors of SNe Ia and the exact
explosion mechanisms are still poorly understood, as are evolutionary
effects on SN Ia peak luminosities. Since early-time UV spectra and
light curves of nearby SNe Ia can directly address these questions, we
propose an approach consisting of two observational components: {1}
Detailed studies of two very bright, young, nearby SNe Ia with HST UV
spectroscopy at 13 epochs within the first 1.5 months after discovery;
and {2} studies of correlations with luminosity for five somewhat more
distant Hubble-flow SNe Ia, for which relative luminosities can be
determined with precision, using 8 epochs of HST UV spectroscopy
and/or broad-band imaging. The HST data, along with extensive
ground-based optical to near-IR observations, will be analyzed with
state-of-the-art models to probe SN Ia explosion physics and constrain
the nature of the progenitors. The results will form the basis for the
next phase of precision cosmology measurements using SNe Ia, allowing
us to more fully capitalize on the substantial past {and future}
investments of time made with HST in observations of high-redshift SNe
Ia.

ACS/HRC/WFC 10389

ACS CCDs daily monitor - Cycle 13 - Part 2

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 program will be
for the entire lifetime of ACS.

ACS/WFC 10471

The Bottom of the Main Sequence in the Old Metal-Rich Cluster NGC 6791

This is the second epoch of GO-9815, whose first-epoch abstract was:
We propose a photometric study of the lowest part of the main sequence
of NGC 6791, an old, rich open cluster whose metallicity is
considerably higher than solar. The cluster is rich enough that a
single ACS/WFC field will have ample stars for the study. For the
faintest stars, proper-motion separation of cluster from field is
essential; hence we include Cycle 14 observations. These should give
us a color-magnitude diagram and luminosity function that reach into
the region of the hydrogen-burning limit, thus extending the study of
the latter into a new domain of metallicity. Observational data of
this type will allow theoreticians to check many aspects of their
theories of stellar structure. We also expect to see the white dwarf
sequence of the cluster. Our team has experience with studies of this
type, and has provided the geometric-distortion calibration of ACS.

ACS/WFC 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/HRC 10536

What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey

Essentially all planetary nebulae {PNs} are aspherical, whereas the
mass-loss envelopes of AGB stars are strikingly spherical. Our
previous SNAPshot surveys of a morphologically unbiased sample of
pre-planetary nebulae {PPNs} -- objects in transition between the AGB
and PN evolutionary phases -- show that roughly half our observed
targets are resolved, with bipolar or multipolar morphologies.
Spectroscopic observations of our sample confirm that these objects
have not yet evolved into planetary nebulae. Thus, the transformation
from spherical to aspherical geometries has already fully developed by
the time these dying stars have become PPNs. Although our current
studies have yielded exciting results, they are limited in two
important ways -- {1} the number of well-resolved objects is still
small {18}, and the variety of morphologies observed relatively
multitudinous, hence no clear trends can yet be established between
morphology and other source properties {e.g., near-IR, far-IR colors,
stellar spectral type, envelope mass}, and {2} the current samples are
strongly biased towards small PPNs, as inferred from their low
60-to-25 micron flux ratios [R{60/25}1]. However, the prototype of
objects with R{60/25}1, the Frosty Leo Nebula, has a puzzlingly large
post- AGB age {almost 10^4 yr} and a fairly cool central star, very
different from the expectations of single-star stellar evolutionary
models. A proposed, but still speculative, hypothesis for such objects
is that the slow evolution of the central star is due to backflow of
material onto the mass-losing star, retarding its evolution towards
the PN phase. This hypothesis has significant consequences for both
stellar and nebular evolution. We therefore propose a survey of PPNs
with R{60/25}1 which is heavily weighted towards the discovery of
such "stalled PPNs". Supporting kinematic observations using long-slit
optical spectroscopy {with the Keck}, millimeter and radio
interferometric observations {with OVRO, VLA & VLBA} are being
undertaken. The results from this survey {together with our previous
work} will allow us to draw general conclusions about the complex
mass-outflow processes affecting late stellar evolution, and will
provide crucial input for theories of post-AGB stellar evolution. Our
survey will produce an archival legacy of long-standing value for
future studies of dying stars.

FGS 10479

The Distance and Mass of the Neutrino-Luminous White Dwarf PG 0122+200

PG 0122+200 is a pulsating hot white dwarf that is believed to radiate
more energy as neutrinos than it does as photons. We propose to
measure with FGS the trigonometric parallax of PG 0122+200 and thereby
determine its distance, luminosity, and mass. Ongoing investigations
from the ground will infer the neutrino luminosity through its effect
on the pulsation periods, thus testing standard and non-standard
lepton theory, but the stellar mass must first be known. The pulsation
spectrum of PG 0122+200 admits two alternative seismological
interpretations, each implying a different mass, luminosity, and
distance. Measurement of an accurate distance will resolve the matter
once and for all and precisely determine the stellar mass. This
project represents the first test of lepton physics in dense {log rho
= 6} plasma and is relevant to the many areas of stellar physics in
which neutrino interactions are important, including recent theories
intended to solve the solar-neutrino problem.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

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 9 9
FGS Reacq 8 8
FHST Update 16 16

SIGNIFICANT EVENTS: (None)