Daily Report # 4339

Notice: For the foreseeable future, the daily reports may contain apparent
discrepancies between some proposal descriptions and the listed instrument
usage. This is due to the conversion of previously approved ACS WFC or HRC
observations into WFPC2, or NICMOS observations subsequent to the loss of
ACS CCD science capability in late January.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4339

PERIOD COVERED: UT April 11, 2007 (DOY 101)

OBSERVATIONS SCHEDULED

ACS/SBC 10872

Lyman Continuum Emission in Galaxies at z=1.2

Lyman continuum photons produced in massive starbursts may have played a
dominant role in the reionization of the Universe. Starbursts are important
contributors to the ionizing metagalactic background at lower redshifts as
well. However, their contribution to the background depends upon the
fraction of ionizing radiation that escapes from the intrinsic opacity of
galaxies below the Lyman limit. Current surveys suggest escape fractions of
a few percent, up to 10%, with very few detections {as opposed to upper
limits} having been reported. No detections have been reported in the epochs
between z=0.1 and z=2. We propose to measure the fraction of escaping Lyman
continuum radiation from 15 luminous z~1.2 galaxies in the GOODS fields.
Using the tremendous sensitivity of the ACS Solar- blind Channel, we will
reach AB=30 mag., allowing us to detect an escape fraction of 1%. We will
correlate the amount of escaping radiation with the photometric and
morphological properties of the galaxies. A non-detection in all sources
would imply that QSOs provide the overwhelming majority of ionizing
radiation at z=1.3, and it would strongly indicate that the properties of
galaxies at higher redshift have to be significantly different for galaxies
to dominate reionization. The deep FUV images will also be useful for
extending the FUV study of other galaxies in the GOODS fields.

WFPC2 10166

ACS and WFPC2 Stellar Photometry in the Kepler Mission Target Field

We will observe three regions at the Galactic Equator {GE} to determine the
number of stars in the magnitude range from 18 to 25 in the target field of
the NASA Kepler mission. This mission will search for Earth-size planets
orbiting other stars. The field is a twelve by twelve degree square in
Cygnus. It abuts the GE. The detection technique is to search
photometrically for planetary transits. Faint eclipsing binaries that are
not spatially resolved from the target star by Kepler may cause confusion,
leading to false positive detections. The HST is uniquely capable of
determining the potential magnitude of the issue in the region of the GE,
where stellar densities are extremely high.

NIC1 11057

Cycle 15 NICMOS dark current, shading profile, and read noise monitoring
program

The purpose of this proposal is to monitor the dark current, read noise, and
shading profile for all three NICMOS detectors throughout the duration of
Cycle 15. This proposal is a slightly modified version of proposal 10380 of
cycle 13 and 9993 of cycle12 and is the same as Cycle 14. that we cut down
some exposure time to make the observation fit within 24 orbits.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

A new proceedure proposed to alleviate the CR-persistence problem of NICMOS.
Dark frames will be obtained immediately upon exiting the SAA contour 23,
and everytime 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.

NIC3 10839

The NICMOS Polarimetric Calibration

Recently, it has been shown that NICMOS possesses an instrumental
polarization at a level of 1.2%. This completely inhibits the data reduction
in a number of previous GO programs, and hampers the ability of the
instrument to perform high accuracy polarimetry. In all, 90 orbits of HST
data are affected, with potentially many more in Cycle 15. We propose to
obtain high signal to noise observations of three polarimetric standards at
the cardinal roll angles of the NICMOS polarizers for both NIC1 and NIC2.
These observations are designed to fully characterize the instrumental
polarization in order for NICMOS to reach its full potential by enabling
high accuracy polarimetry of sources with polarizations around 1%. The
residual polarization will also be determined as a function of position and
spectral energy distribution. Our group will rapidly turn around the
required data products and produce reports and software for the accurate
representation of the instrumental polarization. These items will be
presented to STScI and for dissemination among the wider astronomical
community.

WFPC2 11031

CTE Background Dependence Closeout

Measuring the charge transfer efficiency {CTE} of an astronomical CCD camera
is crucial to determining the CCD's photometric fidelity across the field of
view. WFPC2's CTE has degraded steadily over the last 13 years because of
continuous exposure to trapped particles in HST's radiation environment. The
fraction of photometric signal lost from WFPC2's CTI {charge transfer
inefficiency} is a function of WFPC2's time in orbit, the integrated signal
in the image, the location of the image on the CCD, and the background
signal. Routine monitoring of WFPC2's CTE over the last 13 years permits an
assessment of all but the last condition. The dependence of CTE on
background signal must be characterized, however, because a large fraction
of WFPC2 images have been obtained under conditions of significant sky
background. This program aims to assess the end-of-life CTE of WFPC2's CCDs
separately as a function of background signal. Traditional images of an
off-center field in NGC 5139 {Omega Cen} are recorded after preflashing {or
before postflashing} the CCDs with internal lamps to provide average
background signals of 0-160 e-, which span the range of sky backgrounds
observed in ~99% of long-exposure narrow- and broad-band WFPC2 images.

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 04 04
OBAD with Maneuver 22 22

SIGNIFICANT EVENTS: (None)