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 # 4429
PERIOD
COVERED: UT August 17,18,19, 2007 (DOY 229,230,231)
OBSERVATIONS
SCHEDULED
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 DARKs. 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.
WFPC2
11312
The
Local Cluster Substructure Survey {LoCuSS}: Deep Strong Lensing
Observations
with WFPC2
LoCuSS
is a systematic and detailed investigation of the mass,
substructure,
and thermodynamics of 100 X-ray luminous galaxy clusters
at
0.15<z<0.3. The primary goal is to test our recent suggestion that
this
population is dominated by dynamically immature disturbed clusters,
and
that the observed mass-temperature relation suffers strong
structural
segregation. If confirmed, this would represent a paradigm
shift
in our observational understanding of clusters, that were hitherto
believed
to be dominated by mature, undisturbed systems. We propose to
complete
our successful Cycle 15 program {SNAP:10881} which prior to
premature
termination had delivered robust weak-lensing detections in 17
clusters,
and candidate strongly-lensed arcs in 11 of these 17. These
strong
and weak lensing signals will give an accurate measure of the
total
mass and structure of the dark matter distribution that we will
subsequently
compare with X-ray and Sunyaev Zeldovich Effect
observables.
The broader applications of our project include 1} the
calibration
of mass-temperature and mass-SZE scaling relations which
will
be critical for the calibration of proposed dark energy
experiments,
and 2} the low redshift baseline study of the demographics
of
massive clusters to aid interpretation of future high redshift {z>1}
cluster
samples. To complete the all-important high resolution imaging
component
of our survey, we request deep WFPC2 observations of 20
clusters
through the F606W filter, for which wide-field weak-lensing
data
are already available from our Subaru imaging program. The
combination
of deep WFPC2 and Subaru data for these 20 clusters will
enable
us to achieve the science program approved by the Cycle 15 TAC.
NIC2
11219
Active
Galactic Nuclei in nearby galaxies: a new view of the origin of
the
radio-loud radio- quiet dichotomy?
Using
archival HST and Chandra observations of 34 nearby early-type
galaxies
{drawn from a complete radio selected sample} we have found
evidence
that the radio-loud/radio-quiet dichotomy is directly connected
to
the structure of the inner regions of their host galaxies in the
following
sense: [1] Radio-loud AGN are associated with galaxies with
shallow
cores in their light profiles [2] Radio-quiet AGN are only
hosted
by galaxies with steep cusps. Since the brightness profile is
determined
by the galaxy's evolution, through its merger history, our
results
suggest that the same process sets the AGN flavour. This
provides
us with a novel tool to explore the co-evolution of galaxies
and
supermassive black holes, and it opens a new path to understand the
origin
of the radio-loud/radio-quiet AGN dichotomy. Currently our
analysis
is statistically incomplete as the brightness profile is not
available
for 82 of the 116 targets. Most galaxies were not observed
with
HST, while in some cases the study is obstructed by the presence of
dust
features. We here propose to perform an infrared NICMOS snapshot
survey
of these 82 galaxies. This will enable us to i} test the reality
of
the dichotomic behaviour in a substantially larger sample; ii} extend
the
comparison between radio-loud and radio-quiet AGN to a larger range
of
luminosities.
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.
WFPC2
11203
A
Search for Circumstellar Disks and Planetary-Mass Companions around
Brown
Dwarfs in Taurus
During
a 1-orbit program in Cycle 14, we used WFPC2 to obtain the first
direct
image of a circumstellar disk around a brown dwarf. These data
have
provided fundamental new constraints on the formation process of
brown
dwarfs and the properties of their disks. To search for additional
direct
detections of disks around brown dwarfs and to search for
planetary-mass
companions to these objects, we propose a WFPC2 survey of
32
brown dwarfs in the Taurus star-forming region.
WFPC2
11179
Dynamics
of Clumpy Supersonic Flows in Stellar Jets and in the
Laboratory
We
propose to reobserve three stellar jets in order to quantify how
rapidly
clumps in these flows accelerate and decelerate, and to compare
the
results with ongoing numerical simulations and laboratory
experiments.
Each jet has been imaged twice before with HST, and precise
proper
motions have been measured for all emitting knots in the jets.
Images
from the first two epochs show clear differential motions between
adjacent
clumps, as well as shear, and possibly fragmentation. The
proposed
third epoch will enable us to measure the first ever
accelerations
in jets, quantify errors in existing proper motion
measurements,
and observe in real time how fluid instabilities develop
in
supersonic flows. The new images will make it possible to compare the
behavior
of astrophysical flows directly with numerical simulations and
with
laboratory experiments of bow shocks and clumpy flows in progress
at
the Omega laser facility.
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.
ACS/SBC
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
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
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
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
10787
Modes
of Star Formation and Nuclear Activity in an Early Universe
Laboratory
Nearby
compact galaxy groups are uniquely suited to exploring the
mechanisms
of star formation amid repeated and ongoing gravitational
encounters,
conditions similar to those of the high redshift universe.
These
dense groups host a variety of modes of star formation, and they
enable
fresh insights into the role of gas in galaxy evolution. With
Spitzer
mid-IR observations in hand, we have begun to obtain high
quality,
multi-wavelength data for a well- defined sample of 12 nearby
{<4500km/s}
compact groups covering the full range of evolutionary
stages.
Here we propose to obtain sensitive BVI images with the ACS/WFC,
deep
enough to reach the turnover of the globular cluster luminosity
function,
and WFPC2 U-band and ACS H-alpha images of Spitzer-identified
regions
hosting the most recent star formation. In total, we expect to
detect
over 1000 young star clusters forming inside and outside
galaxies,
more than 4000 old globular clusters in >40 giant galaxies
{including
16 early-type galaxies}, over 20 tidal features,
approximately
15 AGNs, and intragroup gas in most of the 12 groups.
Combining
the proposed ACS images with Chandra observations, UV GALEX
observations,
ground-based H-alpha imaging, and HI data, we will conduct
a
detailed study of stellar nurseries, dust, gas kinematics, and AGN.
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.
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 23 23
FGS
REacq 18 18
OBAD
with Maneuver 82 82
SIGNIFICANT
EVENTS:
We've
received the first internal flat-field images after reducing the
WFPC2
Replacement Heater temperature set points on Tuesday. Everything
looks
good so far. The WF4 CCD bias levels are back in the 290 - 305 DN
range,
which is very close to normal. Changes in optical alignment are
small
and in the expected range. All the images so far look nominal.
We
are reviewing additional calibration data, including images
of
the star cluster Omega Cen, which should provide a good check on the
image
quality. We'll update the status early this week.