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)