Daily Report #4398

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 # 4398

PERIOD COVERED: UT July 05, 2007 (DOY 186)

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.

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is
seriously incomplete for systems in the period range from years to
millennia because the radial velocity variations are too small and the
angular separations too close for easy detection. Here we propose to
discover binaries in this observational gap through a Faint Guidance
Sensor SNAP survey of relatively bright targets listed in the Galactic
O Star Catalog. Our primary goal is to determine the binary frequency
among those in the cluster/association, field, and runaway groups. The
results will help us assess the role of binaries in massive star
formation and in the processes that lead to the ejection of massive
stars from their natal clusters. The program will also lead to the
identification of new, close binaries that will be targets of long
term spectroscopic and high angular resolution observations to
determine their masses and distances. The results will also be
important for the interpretation of the spectra of suspected and newly
identified binary and multiple systems.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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.

NIC3 11062

NICMOS non-linearity tests

This program incorporates a number of tests to analyze the count rate
dependent non- linearity seen in NICMOS spectro-photometric
observations. We will observe a field with stars of a range in
luminosity in NGC3603 with NICMOS in NIC1: F090M, F110W, F140W, F160W
NIC2: F110W, F160W, F187W, F205W, and F222M NIC3: F110W, F150W, F160W,
F175W, and F222M. We will repeat the observations with flatfield lamp
on, creating artificially high count-rates, allowing tests of NICMOS
linearity as function of count rate. We first take exposures with the
lamp off, then exposures with the lamp on, and repeat at the end with
lamp off. Finally, we continue with taking darks during occultation.
We will furthermore observe spectro-photometric standard P041C using
the G096, G141, and G206 grisms in NIC3, and repeat the lamp
off/on/off test to artificially create a high background.

WFPC2 11175

UV Imaging to Determine the Location of Residual Star Formation in
Galaxies Recently Arrived on the Red Sequence

We have identified a sample of low-redshift {z = 0.04 - 0.10} galaxies
that are candidates for recent arrival on the red sequence. They have
red optical colors indicative of old stellar populations, but blue
UV-optical colors that could indicate the presence of a small quantity
of continuing or very recent star formation. However, their spectra
lack the emission lines that characterize star-forming galaxies. We
propose to use ACS/SBC to obtain high- resolution imaging of the UV
flux in these galaxies, in order to determine the spatial distribution
of the last episode of star formation. WFPC2 imaging will provide B,
V, and I photometry to measure the main stellar light distribution of
the galaxy for comparison with the UV imaging, as well as to measure
color gradients and the distribution of interstellar dust. This
detailed morphological information will allow us to investigate the
hypothesis that these galaxies have recently stopped forming stars and
to compare the observed distribution of the last star formation with
predictions for several different mechanisms that may quench star
formation in galaxies.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of
Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens
a window into dynamical conditions in the protoplanetary disk where
they formed as well as the history of subsequent events which sculpted
the outer Solar System and emplaced them onto their present day
heliocentric orbits. To date, at least 47 TNBs have been discovered,
but only about a dozen have had their mutual orbits and separate
colors determined, frustrating their use to investigate numerous
important scientific questions. The current shortage of data
especially cripples scientific investigations requiring statistical
comparisons among the ensemble characteristics. We propose to obtain
sufficient astrometry and photometry of 23 TNBs to compute their
mutual orbits and system masses and to determine separate primary and
secondary colors, roughly tripling the sample for which this
information is known, as well as extending it to include systems of
two near-equal size bodies. To make the most efficient possible use of
HST, we will use a Monte Carlo technique to optimally schedule our
observations.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

#10882 GSacq(2,3,2) fails to RGA control.

Upon acquisition of signal at 187/05:46:34 vehicle was in RGA control.
GSacq(2,3,2) scheduled at 05:17:14 failed to RGA control. 486 ESB
message "A07" ("FGS Coarse Track failed - Time out waiting for Data
Valid") was received. No FGS flags were seen. OBAD prior to GSACQ at
05:12:54 had RSS error of 2.25 arcseconds.

#10883 GSacq(2,3,2) failed, Search Radius Limit exceeded on FGS 2.

Upon acquisition of signal at 187/07:29:15 vehicle was in RGA control
with FGS2 Search Radius Limit and Stop flags set. GSacq(2,3,2)
scheduled at 06:57:57 failed with search radius limit exceeded on FGS
2.

The following 486 ESB messages were received:
06:56:35 ESB 1904 OBAD Too Many Angle Checks
07:03:58 ESB A05 message (FGS Coarse Track failed- search Radius
Limit exceeded)

Post-acquisition OBAD/MAP at 07:48:44 had RSS error of 303.64
arcseconds. OBADs prior to GSACQ are not available.

COMPLETED OPS REQUEST: (None)

****************************** SCHEDULED SUCCESSFUL

FGS GSacq********************** 8*************** 6
FGS REacq********************** 3*************** 3
OBAD with Maneuver****** ****** 23************** 22

COMPLETED OPS NOTES: (None)

SIGNIFICANT EVENTS: (None)