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
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)