HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5098
PERIOD
COVERED: 5am May 17 - 5am May 18, 2010 (DOY 137/09:00z-138/09:00z)
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
11
11
FGS
REAcq
5
5
OBAD
with Maneuver 6
6
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED:
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/FUV/WFC3/UVI
11536
COS-GTO:
Sleuthing the Source of Distant Cometary Activity
Distant
comets and Centaurs often show cometary activity and outbursts well beyond 3
AU, the
boundary
of the sublimation zone of water. Super-volatiles (most likely CO, but possibly
CH4, N2, or
S2)
are suspected to be responsible, but have never been detected in distant comets
in the UV. We
will
obtain FUV spectra of active bodies to cover important CO emission bands. We
plan two sets of
observations:
comet 29P/Schwassmann-Wachmann at 6 AU, whose outbursts are too short to capture
as a
Target
of Opportunity, but which also shows persistent cometary activity in
quiescence; and Target
of
Opportunity observations of the Centaur 2060 Chiron (at ~15.5 AU) in outburst.
COS/NUV
11894
NUV
Detector Dark Monitor
Measure
the NUV detector dark rate by taking long science exposures with no light on
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.
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.
S/C/WFC3/IR
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).
STIS
11849
STIS
CCD Hot Pixel Annealing
This
purpose of this activity is to repair radiation induced hot pixel damage to the
STIS CCD by
warming
the CCD to the ambient instrument temperature and annealing radiation damaged
pixels.
Radiation
damage creates hot pixels in the STIS CCD Detector. Many of these hot pixels
can be
repaired
by warming the CCD from its normal operating temperature near -83 C to the
ambient
instrument
temperature (~ +5 C) for several hours. The number of hot pixels repaired is a
function
of
annealing temperature. The effectiveness of the CCD hot pixel annealing process
is assessed by
measuring
the dark current behavior before and after annealing and by searching for any
window
contamination
effects.
STIS/CCD
11567
Boron
Abundances in Rapidly Rotating Early-B Stars.
Models
of rotation in early-B stars predict that rotationally driven mixing should
deplete surface
boron
abundances during the main-sequence lifetime of many stars. However, recent
work has shown
that
many boron depleted stars are intrinsically slow rotators for which models
predict no depletion
should
have occurred, while observations of nitrogen in some more rapidly rotating
stars show less
mixing
than the models predict. Boron can provide unique information on the earliest
stages of
mixing
in B stars, but previous surveys have been biased towards narrow-lined stars
because of the
difficulty
in measuring boron abundances in rapidly rotating stars. The two targets
observed as part
of
our Cycle 13 SNAP program 10175, just before STIS failed, demonstrate that it
is possible to make
useful
boron abundance measurements for early-B stars with Vsin(i) above 100 km/s. We
propose to
extend
that survey to a large enough sample of stars to allow statistically significant
tests of
models
of rotational mixing in early-B stars.
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.
STIS/CCD
11849
STIS
CCD Hot Pixel Annealing
This
purpose of this activity is to repair radiation induced hot pixel damage to the
STIS CCD by
warming
the CCD to the ambient instrument temperature and annealing radiation damaged
pixels.
Radiation
damage creates hot pixels in the STIS CCD Detector. Many of these hot pixels
can be
repaired
by warming the CCD from its normal operating temperature near -83 C to the
ambient
instrument
temperature (~ +5 C) for several hours. The number of hot pixels repaired is a
function
of
annealing temperature. The effectiveness of the CCD hot pixel annealing process
is assessed by
measuring
the dark current behavior before and after annealing and by searching for any
window
contamination
effects.
STIS/CCD/STIS/MA1
11737
The
Distance Dependence of the Interstellar N/O Abundance Ratio: A Gould Belt
Influence?
The
degree of elemental abundance homogeneity in the interstellar medium is a
function of the
enrichment
and mixing processes that govern Galactic chemical evolution. Observations of
young stars
and
the interstellar gas within ~500 pc of the Sun have revealed a local ISM that
is so well-mixed
it
is having an impact on ideas regarding the formation of extrasolar planets.
However, the
situation
just beyond the local ISM is not so clear. Sensitive UV absorption line
measurements have
recently
revealed a pattern of inhomogeneities in the interstellar O, N, and Kr
gas-phase abundances
at
distances of ~500 pc and beyond that appear nucleosynthetic in origin rather
than due to dust
depletion.
In particular, based on a sample of 13 sightlines, Knauth et al. (2006) have
found that
the
nearby stars (d < 500 pc) exhibit a mean interstellar N/O abundance ratio
that is significantly
higher
(0.18 dex) than that toward the more distant stars. Interestingly, all of their
sightlines
lie
in the sky vicinity of the Gould Belt of OB associations, molecular clouds, and
diffuse gas
encircling
the Sun at a distance of ~400 pc. Is it possible that mixing processes have not
yet
smoothed
out the recent ISM enrichment by massive stars in the young Belt region? By
measuring the
interstellar
N/O ratios in a strategic new sample of sightlines with STIS, we propose to
test the
apparent
N/O homogeneity inside the Gould Belt and determine if the apparent decline in
the N/O
ratio
with distance is robust and associated with the Belt region.
WFC3/IR
11153
The
Physical Nature and Age of Lyman Alpha Galaxies
In
the simplest scenario, strong Lyman alpha emission from high redshift galaxies
would indicate
that
stellar populations younger than 10 Myrs dominate the UV. This does not, however,
constrain the
stellar
populations older than 100 Myrs, which do not contribute to UV light. Also, the
Lyman alpha
line
can be boosted if the interstellar medium is both clumpy and dusty. Different
studies with
small
samples have reached different conclusions about the presence of dust and old
stellar
populations
in Lyman alpha emitters.
We
propose HST-NICMOS and Spitzer-IRAC photometry of 35 Lyman-alpha galaxies at
redshift 4.5<z<6.5,
in
order to determine their spectral energy distribution (SED) extending through
rest-frame optical.
This
will allow us to measure accurately (1) The total stellar mass in these
objects, including old
stars
which may have formed at redshifts (z > 8) not easily probed by any other
means. (2) The dust
extinction
in the rest-frame UV, and therefore a correction to their present
star-formation rates.
Taken
together, these two quantities will yield the star-formation histories of Lyman
alpha
galaxies,
which form fully half of the known galaxies at z=4-6. They will tell us whether
these are
young
or old galaxies by straddling the 4000A break. Data from NICMOS is essential
for these compact
and
faint (i=25-26th magnitude AB) high redshift galaxies, which are too faint for
good near-IR
photometry
from the ground.
WFC3/IR
11838
Completing
a Flux-limited Survey for X-ray Emission from Radio Jets
We
will measure the changing flow speeds, magnetic fields, and energy fluxes in
well-resolved quasar
jets
found in our short-exposure Chandra survey by combining new, deep Chandra data
with radio and
optical
imaging. We will image each jet with sufficient sensitivity to estimate beaming
factors and
magnetic
fields in several distinct regions, and so map the variations in these
parameters down the
jets.
HST observations will help diagnose the role of synchrotron emission in the
overall SED, and
may
reveal condensations on scales less than 0.1 arcsec.
WFC3/UVI
11360
Star
Formation in Nearby Galaxies
Star
formation is a fundamental astrophysical process; it controls phenomena ranging
from the
evolution
of galaxies and nucleosynthesis to the origins of planetary systems and abodes
for life.
The
WFC3, optimized at both UV and IR wavelengths and equipped with an extensive
array of
narrow-band
filters, brings unique capabilities to this area of study. The WFC3 Scientific
Oversight
Committee
(SOC) proposes an integrated program on star formation in the nearby universe
which will
fully
exploit these new abilities. Our targets range from the well-resolved R136 in
30 Dor in the
LMC
(the nearest super star cluster) and M82 (the nearest starbursting galaxy) to
about half a dozen
other
nearby galaxies that sample a wide range of star-formation rates and
environments. Our program
consists
of broad-band multiwavelength imaging over the entire range from the UV to the
near-IR,
aimed
at studying the ages and metallicities of stellar populations, revealing young
stars that are
still
hidden by dust at optical wavelengths, and showing the integrated properties of
star clusters.
Narrow-band
imaging of the same environments will allow us to measure star-formation rates,
gas
pressure,
chemical abundances, extinction, and shock morphologies. The primary scientific
issues to
be
addressed are: (1) What triggers star formation? (2) How do the properties of
star-forming
regions
vary among different types of galaxies and environments of different gas
densities and
compositions?
(3) How do these different environments affect the history of star formation?
(4) Is
the
stellar initial mass function universal or determined by local conditions?
WFC3/UVI
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<BR>and
dark frames. A smaller set of 2Kx4K subarray biases are acquired at less
frequent
intervals<BR>throughout
the cycle to support subarray science observations. The internals from this
proposal,<BR>along
with those from the anneal procedure (11909), will be used to generate the
necessary
superbias<BR>and superdark reference files for the calibration pipeline
(CDBS).
WFC3/UVI
12018
Ultra-Luminous
x-Ray Sources in the Most Metal-Poor Galaxies
There
is growing observational and theoretical evidence to suggest that
Ultra-Luminous X-ray sources
(ULX)
form preferentially in low metallicity environments. Here we propose a survey
of 27 nearby (<
30Mpc)
star-forming Extremely Metal Poor Galaxies (Z<5% solar). There are almost no
X-ray
observations
of such low abundance galaxies (3 in the Chandra archive). These are the most
metal-deficient
galaxies known, and a logical place to find ULX if they favor metal-poor
systems. We
plan
to test recent population synthesis models which predict that ULX should be
very numerous in
metal-poor
galaxies. We will also test the hypothesis that ULX form in massive young star
clusters,
and
ask for HST time to obtain the necessay imaging data.