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Daily Report #5191



 
 
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Old September 29th 10, 03:55 PM posted to sci.astro.hubble
Bassford, Lynn
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Default Daily Report #5191


HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5191

PERIOD COVERED: 8:00pm September 27 - 7:59pm September 28, 2010 (DOY 271/00:00z-271/23:59z)

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 8 8
FGS REAcq 8 8
OBAD with Maneuver 6 6

SIGNIFICANT EVENTS: (None)

OBSERVATIONS SCHEDULED:

ACS/WFC3 11882

CCD Hot Pixel Annealing

This program continues the monthly anneal that has taken place every
four weeks for the last three cycles. We now obtain WFC biases and
darks before and after the anneal in the same sequence as is done for
the ACS daily monitor (now done 4 times per week). So the anneal
observation supplements the monitor observation sets during the
appropriate week. Extended Pixel Edge Response (EPER) and First Pixel
Response (FPR) data will be obtained over a range of signal levels for
the Wide Field Channel (WFC). This program emulates the ACS pre-flight
ground calibration and post-launch SMOV testing (program 8948), so
that results from each epoch can be directly compared. The High
Resolution Channel (HRC) visits have been removed since it could not
be repaired during SM4.

This program also assesses the read noise, bias structure, and
amplifier cross-talk of ACS/WFC using the GAIN=1.4 A/D conversion
setting. This investigation serves as a precursor to a more
comprehensive study of WFC performance using GAIN=1.4.

COS/NUV/FUV 11535

COS-GTO: Deep Search for an Oxygen Atmosphere on Callisto

We plan a deep search for 1304? and 1356? O emission from Callisto, to
detect or place strong limits on the presence of a hypothesized O2
atmosphere on this moon (Liang et al. 2005). Tenuous oxygen
atmospheres on Europa and Ganymede have been detected by HST using
these emission lines, but searches for O emission from Callisto have
not been successful (Strobel et al. 2002). The Liang et al. models
predict O emission at levels comparable to the Strobel et al. upper
limit, so the improved sensitivity of COS may be able to detect the
emission, and thus Callisto's O2 atmosphere, for the first time.

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current
draw information is collected, monitored, and saved to DCE memory.
Every 10 msec the detector samples the currents from the HV power
supplies (HVIA, HVIB) and the AUX power supply (AUXI). The last 1000
samples are saved in memory, along with a histogram of the number of
occurrences of each current value.

In the case of a HV transient (known as a "crackle" on FUSE), where
one of these currents exceeds a preset threshold for a persistence
time, the HV will shut down, and the DCE memory will be dumped and
examined as part of the recovery procedure. However, if the current
exceeds the threshold for less than the persistence time (a
"mini-crackle" in FUSE parlance), there is no way to know without
dumping DCE memory. By dumping and examining the histograms regularly,
we will be able to monitor any changes in the rate of "mini-crackles"
and thus learn something about the state of the detector.

STIS/CCD 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,
and 1x1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.

WFC3/IR 12307

A public SNAPSHOT Survey of Gamma-ray Burst Host Galaxies

We propose to conduct a public infrared survey of the host galaxies of
Swift selected gamma-ray bursts (GRBs) at z3. By obtaining deep,
diffraction limited imaging in the IR we will complete detections for
the host galaxies, and in concert with our extensive ground based
afterglow and host programmes will compile a detailed catalog of the
properties of high-z galaxies selected by GRBs. In particular these
observations will enable us to study the colours, luminosities and
morphologies of the galaxies. This in turn informs studies of the
nature of the progenitors and the role of GRBs as probes of star
formation across cosmic history. Ultimately it provides a product of
legacy value which will greatly complement further studies with next
generation facilities such as ALMA and JWST.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more
reliably removed from science data using darks taken with the same
exposure sequences as the science data, than with a single dark
current image scaled by desired exposure time. Therefore, dark current
images must be collected using all sample sequences that will be used
in science observations. These observations will be used to monitor
changes in the dark current of the WFC3-IR channel on a day-to-day
basis, and to build calibration dark current ramps for each of the
sample sequences to be used by Gos in Cycle 17. For each sample
sequence/array size combination, a median ramp will be created and
delivered to the calibration database system (CDBS).

WFC3/UV 11635

In Search of SNIb/Ic Wolf-Rayet Progenitors and Comparison with Red
Supergiants (SNII Progenitors) in the Giant ScI Spiral M101

We propose to test two of the clearest predictions of the theory of
evolution of massive-star evolution: 1) The formation of Wolf-Rayet
stars depends strongly on these stars' metallicity (Z), with
relatively fewer WR stars forming at lower Z, and 2) Wolf-Rayet stars
die as Type Ib or Ic supernovae. To carry out these tests we propose a
deep, narrowband imaging survey of the massive star populations in the
ScI spiral galaxy M101. Just as important, we will test the hypothesis
that Superclusters like 30 Doradus are always richly populated with WR
stars, and by implication that these complexes are responsible for the
spectral signatures of starburst galaxies.

Our previous HST survey of the HII regions in the ScIII galaxy NGC
2403 suggested that the distribution of WR stars and RSG is a
sensitive diagnostic of the recent star-forming history of these large
complexes: young cores of O and WR stars are surrounded by older halos
containing RSG. Theory predicts that this must change with
metallicity; relatively fewer WR stars form at lower Z. A key goal of
our proposal is to directly test this paradigm in a single galaxy,
M101 being the ideal target. The abundance gradient across M101 (a
factor of 20) suggests that relatively many more WR will be found in
the inner parts of this galaxy than in the outer "suburbs". Second, we
note that WR stars are predicted to end their lives as core-collapse
or pair-instability supernovae. The WR population in M101 may be
abundant enough for one to erupt as a Type Ib or Ic supernova within a
generation. The clear a priori identification of a WR progenitor would
be a major legacy of HST. Third, we will also determine if
"superclusters", heavily populated by WR stars, are common in M101. It
is widely claimed that such Superclusters produce the integrated
spectral signatures of Starburst galaxies. We will be able to directly
measure the numbers and emission-line luminosities of thousands of
Wolf Rayet stars located in hundreds of M101 Superclusters, and
correlate those numbers against the Supercluster sizes and
luminosities. It is likely (but far from certain) that Supercluster
sizes and emission-line luminosities are driven by their Wolf-Rayet
star content. Our sample will be the largest and best-ever
Supercluster/Wolf Rayet sample, an excellent local proxy for
characterizing starburst galaxies' Superclusters.

WFC3/UV 12348

WFC3/UVIS Charge Injection Test

In preparation for making charge injection (CI) available to
observers, this proposal will 1) confirm that the CI performs on-orbit
as it did on the ground, 2) provide an initial assessment of which CI
mode is most effective (10, 17, 25 line or continuous), and 3) obtain
a baseline calibration for each mode.

WFC3/UV/IR 11664

The WFC3 Galactic Bulge Treasury Program: Populations, Formation
History, and Planets

Exploiting the full power of the Wide Field Camera 3 (WFC3), we
propose deep panchromatic imaging of four fields in the Galactic
bulge. These data will enable a sensitive dissection of its stellar
populations, using a new set of reddening-free photometric indices we
have constructed from broad-band filters across UV, optical, and
near-IR wavelengths. These indices will provide accurate temperatures
and metallicities for hundreds of thousands of individual bulge stars.
Proper motions of these stars derived from multi-epoch observations
will allow separation of pure bulge samples from foreground disk
contamination. Our catalogs of proper motions and panchromatic
photometry will support a wide range of bulge studies.

Using these photometric and astrometric tools, we will reconstruct the
detailed star-formation history as a function of position within the
bulge, and thus differentiate between rapid- and extended-formation
scenarios. We will also measure the dependence of the stellar mass
function on metallicity, revealing how the characteristic mass of star
formation varies with chemistry. Our sample of bulge stars with
accurate metallicities will include 12 candidate hosts of extrasolar
planets. Planet frequency is correlated with metallicity in the solar
neighborhood; our measurements will extend this knowledge to a remote
environment with a very distinct chemistry.

Our proposal also includes observations of six well-studied globular
and open star clusters; these observations will serve to calibrate our
photometric indices, provide empirical population templates, and
transform the theoretical isochrone libraries into the WFC3 filter
system. Besides enabling our own program, these products will provide
powerful new tools for a host of other stellar-population
investigations with HST/WFC3. We will deliver all of the products from
this Treasury Program to the community in a timely fashion.

WFC3/UVIS 11729

Photometric Metallicity Calibration with WFC3 Specialty Filters

The community has chosen to include several filters in the WFC3 filter
complement that have been designed to allow fairly precise estimates
of stellar metallicities, and many science programs are enabled by
this capability. Since these filters do not exactly match those used
for this purpose on the ground, however, the mapping of stellar colors
to stellar metallicities needs to be calibrated. We propose to achieve
this calibration through observations of five stellar clusters with
well known metallicities. We will calibrate several different filter
calibrations which will allow future users to determine what filter
combination best meets their science needs.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set
of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K
subarray biases are acquired at less frequent intervals throughout the
cycle to support subarray science observations. The internals from
this proposal, along with those from the anneal procedure (Proposal
11909), will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the
UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially found via an unexpected bowtie- shaped feature in flatfield
ratios, subsequent lab tests on similar e2v devices have since shown
that it is also present as simply an overall offset across the entire
CCD, i.e., a QE offset without any discernable pattern. These lab
tests have further revealed that overexposing the detector to count
levels several times full well fills the traps and effectively
neutralizes the bowtie. Each visit in this proposal acquires a set of
three 3x3 binned internal flatfields: the first unsaturated image will
be used to detect any bowtie, the second, highly exposed image will
neutralize the bowtie if it is present, and the final image will allow
for verification that the bowtie is gone.

WFC3/UVIS/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into
the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass,
but their small numbers, coupled with their stochastic pasts, make it
impossible to construct a unique formation history from the dynamical
or compositional characteristics of them alone. In contrast, the huge
numbers of small bodies scattered throughout and even beyond the
planets, while insignificant by mass, provide an almost unlimited
number of probes of the statistical conditions, history, and
interactions in the solar system. To date, attempts to understand the
formation and evolution of the Kuiper Belt have largely been dynamical
simulations where a hypothesized starting condition is evolved under
the gravitational influence of the early giant planets and an attempt
is made to reproduce the current observed populations. With little
compositional information known for the real Kuiper Belt, the test
particles in the simulation are free to have any formation location
and history as long as they end at the correct point. Allowing
compositional information to guide and constrain the formation,
thermal, and collisional histories of these objects would add an
entire new dimension to our understanding of the evolution of the
outer solar system. While ground based compositional studies have hit
their flux limits already with only a few objects sampled, we propose
to exploit the new capabilities of WFC3 to perform the first ever
large-scale dynamical-compositional study of Kuiper Belt Objects
(KBOs) and their progeny to study the chemical, dynamical, and
collisional history of the region of the giant planets. The
sensitivity of the WFC3 observations will allow us to go up to two
magnitudes deeper than our ground based studies, allowing us the
capability of optimally selecting a target list for a large survey
rather than simply taking the few objects that can be measured, as we
have had to do to date. We have carefully constructed a sample of 120
objects which provides both overall breadth, for a general
understanding of these objects, plus a large enough number of objects
in the individual dynamical subclass to allow detailed comparison
between and within these groups. These objects will likely define the
core Kuiper Belt compositional sample for years to come. While we have
many specific results anticipated to come from this survey, as with
any project where the field is rich, our current knowledge level is
low, and a new instrument suddenly appears which can exploit vastly
larger segments of the population, the potential for discovery -- both
anticipated and not -- is extraordinary.

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