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 # 4435
PERIOD
COVERED: UT August 27, 2007 (DOY 239)
OBSERVATIONS
SCHEDULED
WFPC2
10599
Multi-color
imaging of two 1 Gyr old debris disks within 20 pc of the
Sun:
Astrophysical mirrors of our Kuiper Belt
We
report the first scattered light detections of two debris disk around
an
F star and a K star using optical coronagraphy and the Hubble Space
Telescope.
With ages ~1 Gyr, these are the oldest debris disks thus far
seen
in the optical. We propose deep, multi-roll angle coronagraphic
imaging
with HST ACS and NICMOS to confirm and characterize the disks in
terms
of structure and composition. The disks appear to have belt-like
morphology
that is consistent with the existence of planetary companions
or
other perturbing bodies. Since these disks are close to our Kuiper
Belt
in an evolutionary context, detailed understanding of their mass,
structure
and composition will provide a fresh perspective for inferring
the
history and properties of our own trans-Neptunian region.
WFPC2
11024
WFPC2
CYCLE 15 INTERNAL MONITOR
This
calibration proposal is the Cycle 15 routine internal monitor for
WFPC2,
to be run weekly to monitor the health of the cameras. A variety
of
internal exposures are obtained in order to provide a monitor of the
integrity
of the CCD camera electronics in both bays {both gain 7 and
gain
15 -- to test stability of gains and bias levels}, a test for
quantum
efficiency in the CCDs, and a monitor for possible buildup of
contaminants
on the CCD windows. These also provide raw data for
generating
annual super-bias reference files for the calibration
pipeline.
FGS
11018
Long
Term Stability of FGS1r in Position Mode
It
is known from our experience with FGS3, and later with FGS1r, that an
FGS
on orbit experiences long term evolution, presumably due to
disorption
of water from the instrument's graphite epoxy composits. This
manifests
principly as a change in the plate scale and secondarily as a
change
in the geometric distortions. These effects are well modeled by
adjustments
to the rhoA and kA parameters which are used to transform
the
star selector servo angles into FGS {x, y} detector space
coordinates.
By observing the relative positions of selected stars in a
standard
cluster at a fixed telescope pointing and orientation, the
evolution
of rhoA and kA can be monitored and calibrated to preserve the
astrometric
performance of FGS1r.
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.
WEPC2
11196
An
Ultraviolet Survey of Luminous Infrared Galaxies in the Local
Universe
At
luminosities above 10^11.4 L_sun, the space density of far-infrared
selected
galaxies exceeds that of optically selected galaxies. These
Luminous
Infrared Galaxies {LIRGs} are primarily interacting or merging
disk
galaxies undergoing starbursts and creating/fueling central AGN. We
propose
far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV imaging of a
sample
of 27 galaxies drawn from the complete IRAS Revised Bright Galaxy
Sample
{RBGS} LIRGs sample and known, from our Cycle 14 B and I-band ACS
imaging
observations, to have significant numbers of bright {23 < B < 21
mag}
star clusters in the central 30 arcsec. The HST UV data will be
combined
with previously obtained HST, Spitzer, and GALEX images to {i}
calculate
the ages of the clusters as function of merger stage, {ii}
measure
the amount of UV light in massive star clusters relative to
diffuse
regions of star formation, {iii} assess the feasibility of using
the
UV slope to predict the far- IR luminosity {and thus the star
formation
rate} both among and within IR-luminous galaxies, and {iv}
provide
a much needed catalog of rest-frame UV morphologies for
comparison
with rest-frame UV images of high-z LIRGs and Lyman Break
Galaxies.
These observations will achieve the resolution required to
perform
both detailed photometry of compact structures and spatial
correlations
between UV and redder wavelengths for a physical
interpretation
our IRX-Beta results. The HST UV data, combined with the
HST
ACS, Spitzer, Chandra, and GALEX observations of this sample, will
result
in the most comprehensive study of luminous starburst galaxies to
date.
WFPC2
11023
WFPC2
CYCLE 15 Standard Darks - part 1
This
dark calibration program obtains dark frames every week in order to
provide
data for the ongoing calibration of the CCD dark current rate,
and
to monitor and characterize the evolution of hot pixels. Over an
extended
period these data will also provide a monitor of radiation
damage
to the CCDs.
WFPC2
11030
WFPC2
WF4 Temperature Reduction #3
In the
fall of 2005, a serious anomaly was found in images from the WF4
CCD
in WFPC2. The WF4 CCD bias level appeared to have become unstable,
resulting
in sporadic images with either low or zero bias level. The
severity
and frequency of the problem was rapidly increasing, making it
possible
that WF4 would soon become unusable if no work-around were
found.
Examination of bias levels during periods with frequent WFPC2
images
showed low and zero bias episodes every 4 to 6 hours. This
periodicity
is driven by cycling of the WFPC2 Replacement Heater, with
the
bias anomalies occurring at the temperature peaks. The other three
CCDs
{PC1, WF2, and WF3} appear to be unaffected and continue to operate
properly.
Lowering the Replacement Heater temperature set points by a
few
degrees C effectively eliminates the WF4 anomaly. On 9 January 2006,
the
upper set point of the WFPC2 Replacement Heater was reduced from
14.9C
to 12.2C. On 20 February 2006, the upper set point was reduced
from
12.2C to 11.3C, and the lower set point was reduced from 10.9C to
10.0C.
These changes restored the WF4 CCD bias level; however, the bias
level
has begun to trend downwards again, mimicking its behavior in late
2004
and early 2005. A third temperature reduction is planned for March
2007.
We will reduce the upper set point of the heater from 11.3C to
10.4C
and the lower set point from 10.0C to 9.1C. The observations
described
in this proposal will test the performance of WFPC2 before and
after
this temperature reduction. Additional temperature reductions may
be
needed in the future, depending on the performance of WF4. Orbits:
internal
26, external 1
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
11113
Binaries
in the Kuiper Belt: Probes of Solar System Formation and
Evolution
The
discovery of binaries in the Kuiper Belt and related small body
populations
is powering a revolutionary step forward in the study of
this
remote region. Three quarters of the known binaries in the Kuiper
Belt
have been discovered with HST, most by our snapshot surveys. The
statistics
derived from this work are beginning to yield surprising and
unexpected
results. We have found a strong concentration of binaries
among
low-inclination Classicals, a possible size cutoff to binaries
among
the Centaurs, an apparent preference for nearly equal mass
binaries,
and a strong increase in the number of binaries at small
separations.
We propose to continue this successful program in Cycle 16;
we
expect to discover at least 13 new binary systems, targeted to
subgroups
where these discoveries can have the greatest impact.
WFPC2
11156
Monitoring
Active Atmospheres on Uranus and Neptune
We
propose Snapshot observations of Uranus and Neptune to monitor
changes
in their atmospheres on time scales of weeks and months. Uranus
equinox
is only months away, in December 2007. Hubble Space Telescope
observations
during the past several years {Hammel et al. 2005, Icarus
175,
284 and references therein} have revealed strongly
wavelength-dependent
latitudinal structure, the presence of numerous
visible-wavelength
cloud features in the northern hemisphere, at least
one
very long-lived discrete cloud in the southern hemisphere, and in
2006
the first dark spot ever seen on Uranus. Long-term ground-based
observations
{Lockwood and Jerzekiewicz, 2006, Icarus 180, 442; Hammel
and
Lockwood 2007, Icarus 186, 291} reveal seasonal brightness changes
whose
origins are not well understood. Recent near-IR images of
obtained
using adaptive optics on the Keck Telescope, together with HST
observations
{Sromovsky et al. 2003, Icarus 163, 256 and references
therein}
which include previous Snapshot programs {GO 8634, 10170,
10534}
show a general increase in activity at south temperate latitudes
until
2004, when
Further
Snapshot observations of these two dynamic planets will
elucidate
the nature of long-term changes in their zonal atmospheric
bands
and clarify the processes of formation, evolution, and dissipation
of
discrete albedo features.
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:
10961
- REacq(2,1,1) results in fine lock backup (2,0,2) using FGS-2
The REacq(2,1,1) scheduled at 239/19:37:08 - 19:45:12 resulted in
fine
lock backup (2,0,2) using FGS-2 due to (QF1STOPF) stop flag
indication
on FGS-1. Pre-acquisition OBADs showed (RSS) attitude correction
values
of 868.94 and 7.06 arcseconds. Post-acquisition OBAD/MAP had (RSS)
value
of 15.80 arcseconds.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
08
08
FGS
REacq
06
04
OBAD
with Maneuver 24
24
SIGNIFICANT
EVENTS: (None)