Daily Report #4457

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science
capability in January, there may be an occasional discrepancy between
a proposal's listed (and correct) instrument usage and the abstract
that follows it.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT***** # 4457

PERIOD COVERED: UT September 27, 2007 (DOY 270)

OBSERVATIONS SCHEDULED

WFPC2 10909

Exploring the diversity of cosmic explosions: The supernovae of
gamma-ray bursts

While the connection between gamma-ray bursts {GRBs} and supernovae
{SNe} is now clearly established, there is a large variety of
observational properties among these SNe and the physical parameters
of these explosions are poorly known. As part of a comprehensive
program, we propose to use HST in order to obtain basic information
about the supernovae associated with gamma-ray bursts. HST offers the
means to cleanly separate the light curves of the GRB afterglow from
the supernova, and to remove the contamination from the host galaxy,
opening a clear route to the fundamental parameters of the SN. From
these observations, we will determine the absolute magnitude at
maximum, the shape of the spectral energy distribution, and any change
over time of the energy distribution. We will also measure the rate of
decay of the exponential tail. Merged with the ground-based data that
we will obtain for each event, we will be able to compare our data set
to models and constrain the energy of the explosion, the mass of the
ejecta and the mass of Nickel synthesized during the explosion. These
results will shed light on the apparent variety of supernovae
associated with gamma-ray bursts and X-ray flashes, and on the
relation between these SNe and other, more common varieties of
core-collapse explosions.

FGS 10930

Mass and Radius of a Near-Chandrasekhar-limit magnetic white dwarf

REJ0317-853 is a unique object. According to our analyses it is the
most massive white dwarf ever found, with a mass of 1.35 solar masses,
approaching the Chandrasekhar limit. With a period of just 725 seconds
it is the most rapidly rotating isolated white dwarf ever found.
Moreover, RE J0317-853 is the hottest magnetic white dwarf discovered
so far and has a strong magnetic field varying from about 180 to more
than 700 MG over the stellar surface. Due to its strong polarization
and high mass it has been used to test gravitational theories
predicting gravitational birefringence. However, the existing mass and
radius determination is indirect and still uncertain and would greatly
profit from a high-precision parallax determination with the HST FGS.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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 i mages. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

WFPC2 11033

Full Moon Earth Flats Closeout

Flat field exposures will be obtained by observing the moonlit Earth
with the broadband WFPC2 filters F606W and F814W, which saturate in
the minimum exposure time on the sunlit Earth. These observations will
be used to improve the flats currently in the pipeline and are part of
the WFPC2 closeout operations. Because CTE effects are large for star
flats and small for full field illumination, Earth flats are the
superior technique.

WFPC2 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still
largely an open problem in cosmology: how does the Universe evolve
from large linear scales dominated by dark matter to the highly
non-linear scales of galaxies, where baryons and dark matter both play
important, interacting, roles? To understand the complex physical
processes involved in their formation scenario, and why they have the
tight scaling relations that we observe today {e.g. the Fundamental
Plane}, it is critically important not only to understand their
stellar structure, but also their dark-matter distribution from the
smallest to the largest scales. Over the last three years the SLACS
collaboration has developed a toolbox to tackle these issues in a
unique and encompassing way by combining new non-parametric strong
lensing techniques, stellar dynamics, and most recently weak
gravitational lensing, with high-quality Hubble Space Telescope
imaging and VLT/Keck spectroscopic data of early-type lens systems.
This allows us to break degeneracies that are inherent to each of
these techniques separately and probe the mass structure of early-type
galaxies from 0.1 to 100 effective radii. The large dynamic range to
which lensing is sensitive allows us both to probe the clumpy
substructure of these galaxies, as well as their low-density outer
haloes. These methods have convincingly been demonstrated, by our
team, using smaller pilot-samples of SLACS lens systems with HST data.
In this proposal, we request observing time with WFPC2 and NICMOS to
observe 53 strong lens systems from SLACS, to obtain complete
multi-color imaging for each system. This would bring the total number
of SLACS lens systems to 87 with completed HST imaging and effectively
doubles the known number of galaxy-scale strong lenses. The deep HST
images enable us to fully exploit our new techniques, beat down
low-number statistics, and probe the structure and evolution of
early-type galaxies, not only with a uniform data-set an order of
magnitude larger than what is available now, but also with a fully
coherent and self-consistent methodological approach!

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**************** 03**************** 03
FGS REacq**************** 11***************** 11
OBAD with Maneuver** ** * 28***************** 28

SIGNIFICANT EVENTS: (None)