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)