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)