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Daily Report #5083



 
 
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Old April 27th 10, 03:47 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #5083

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5083

PERIOD COVERED: 5am April 26 - 5am April 27, 2010 (DOY 116/09:00z-117/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC 11995

CCD Daily Monitor (Part 2)

This program comprises basic tests for measuring the read noise and
dark current of the ACS WFC and for tracking the growth of hot pixels.
The recorded frames are used to create bias and dark reference images
for science data reduction and calibration. This program will be
executed four days per week (Mon, Wed, Fri, Sun) for the duration of
Cycle 17. To facilitate scheduling, this program is split into three
proposals. This proposal covers 320 orbits (20 weeks) from 1 February
2010 to 20 June 2010.

ACS/WFC3 11669

The Origins of Short Gamma-Ray Bursts

During the past decade extraordinary progress has been made in
determining the origin of long- duration gamma-ray bursts. It has been
conclusively shown that these objects derive from the deaths of
massive stars. Nonetheless, the origin of their observational cousins,
short-duration gamma-ray bursts (SGRBs) remains a mystery. While SGRBs
are widely thought to result from the inspiral of compact binaries,
this is a conjecture. SGRBs have been found in elliptical galaxies,
Abell Clusters, star-forming dwarfs and even an edge-on spiral.
Whether they primarily result from an old population, a young
population, or rapid evolution of binaries in globular clusters
remains open.

Here we propose to employ two related sets of observations which may
dramatically advance our understanding of short bursts. The first is a
variant of a technique that we pioneered and used to great effect in
elucidating the origins of long-duration bursts. We will examine a
statistical sample of hosts and measure the degree to which SGRB
locations trace the red or blue light of their hosts, and thus old or
young stellar populations. This will allow us to study the
demographics of the SGRB population in a manner largely free of the
distance dependent selection effects which have so far bedeviled this
field. In the second line of attack we will use two targets of
opportunity to obtain extremely precise positions of up to two nearby
bursts -- one on a star-forming galaxy and the other on a elliptical.
Observation of the star-formation galaxy could link at least some
bursts directly to a young population; however, a discovery in later
images of a globular cluster at the site of the explosion in an
elliptical would provide revolutionary evidence that SGRBs are formed
from compact binaries.

COS/FUV 11895

FUV Detector Dark Monitor

Monitor the FUV detector dark rate by taking long science exposures
without illuminating the detector. The detector dark rate and spatial
distribution of counts will be compared to pre-launch and SMOV data in
order to verify the nominal operation of the detector. Variations of
count rate as a function of orbital position will be analyzed to find
dependence of dark rate on proximity to the SAA. Dependence of dark
rate as function of time will also be tracked.

COS/NUV 11896

NUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity of each NUV
grating mode to detect any changes due to contamination or other
causes.

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/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CC 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.

STIS/MA/CC 12079

STIS PtCr/Ne Lamp Ratios

We will provide improved information on the ratio of the STIS
wavelength calibration lamps at all wavelengths. The LINE & HITM1
lamps have faded by a factor of several since launch, and at the
shortest wavelengths the fading is enough to have significantly
impacted the S/N of the wavecals. The FUV flux of the HITM2 lamp has
not been checked since 1997, and so a detailed comparison of all three
lamps is needed to support a proper wavelength calibration for GO
proposals.

WFC3/UV/ACS/WFC 11636

First Resolved Imaging of Escaping Lyman Continuum

The emission from star-forming galaxies appears to be responsible for
reionization of the universe at z 6. However, the models that
attempt to describe the detailed impact of high-redshift galaxies on
the surrounding inter-galactic medium (IGM) are strongly dependent
upon several uncertain parameters. Perhaps the most uncertain is the
fraction of HI-ionizing photons produced by young stars that escape
into the IGM. Most attempts to measure this "escape fraction" have
produced null results. Recently, a small subset of z~3 Lyman Break
Galaxies (LBGs) has been found exhibiting large escape fractions. It
remains unclear however, what differentiates them from other LBGs.
Several models attempt to explain how such a large fraction of
ionizing continuum can escape through the HI and dust in the ISM (eg.
"chimneys" created by SNe winds, globular cluster formation, etc.),
each producing unique signatures which can be observed with resolved
imaging of the escaping Lyman continuum. To date, there are only six
LBGs with individual detections of escaping Lyman continuum at any
redshift. We propose a single deep, high resolution WFC3/UVIS image of
the ionizing continuum (F336W) and the rest-frame UV/optical
(F606W/F814W/F160W) of five of these six LBGs with large escape
fractions. These LBGs have a high surface density and large escape
fractions, and lie at the optimal redshift for Lyman continuum imaging
with UVIS filters, making our sample especially suitable for
follow-up. With these data we will discern the mechanisms responsible
for producing large escape fractions, and therefore gain insight into
the process of reionization.

WFC3/UVIS 11650

Mutual Orbits, Colors, Masses, and Bulk Densities of 3 Cold Classical
Trans-Neptunian Binaries

Many Trans-Neptunian Objects (TNOs) have been found to be binary or
multiple systems. As in other astrophysical settings, Trans-Neptunian
Binaries (TNBs) offer uniquely valuable information. Their mutual
orbits allow the direct determination of their system masses, perhaps
the most fundamental physical quantity of any astronomical object.
Their frequency of occurrence and dynamical characteristics provide
clues to formation conditions and evolution scenarios affecting both
the binaries and their single neighbors. Combining masses with sizes,
bulk densities can be measured. Densities constrain bulk composition
and internal structure, key clues to TNO origins and evolution over
time. Several TNB bulk densities have been determined, hinting at
interesting trends. But none of them belongs to the Cold Classical
sub-population, the one group of TNOs with demonstrably distinct
physical characteristics. Two top-priority Spitzer programs will soon
observe and measure the sizes of 3 Cold Classical TNBs. This proposal
seeks to determine the mutual orbits and thus masses of these systems,
enabling computation of their densities.

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.

WFPC2 11340

X-ray Observations of 11 Millisecond Pulsars in M28

We propose a deep X-ray survey of the globular cluster M28 which will
yield a wealth of important and unique science, ranging from the first
direct measurement of the magnetic field of a millisecond pulsar and
constraints on the neutron star equation of state to likely
X-ray/optical (HST) detection of a re-exchanged binary MSP. The
proposed joint HST WFPC2 observation will tie the X-ray, optical, and
radio data to a common astrometric frame allowing an unambiguous
identification of numerous cataclysmic variables and active binaries
in M28 as well as making possible the first direct optical detection
of a millisecond pulsar.

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 07 07
FGS REAcq 09 09
OBAD with Maneuver 07 07

SIGNIFICANT EVENTS: (None)

 




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