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HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5192
PERIOD
COVERED: 8pm September 28 - 7:59pm September 29, 2010 (DOY
272/00:00z-272/23:59z)
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
12436
- OBAD at 272/01:25z, GSAcq(2,1,1) at 272/01:32z and REAcq at 272/02:44:05z all
failed with Search Radius Limit exceeded on FGS2.
Observations affected: ACS 35-38, Proposal ID#12381
HSTAR
FOR DOY 261
12439
- REAcq(1,2,1) at 261/01:32:50z received a stop flag on FGS1 three
times before achieving FL-DV. The acquisition was successful.
Observations possibly affected: COS 41-46 Proposal ID#11896; STIS
95-97 Proposal ID#11847.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
Scheduled Successful
FGS
GSAcq
8
7
FGS
REAcq
8
7
OBAD
with Maneuver 7
7
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED:
ACS/WFC
11996
CCD
Daily Monitor (Part 3)
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 308 orbits (19.25 weeks) from 21 June 2010 to 1 November
2010.
ACS/WFC
12210
SLACS
for the Masses: Extending Strong Lensing to Lower Masses and
Smaller
Radii
Strong
gravitational lensing provides the most accurate possible
measurement
of mass in the central regions of early-type galaxies
(ETGs).
We propose to continue the highly productive Sloan Lens ACS
(SLACS)
Survey for strong gravitational lens galaxies by observing a
substantial
fraction of 135 new ETG gravitational-lens candidates with
HST-ACS
WFC F814W Snapshot imaging. The proposed target sample has been
selected
from the seventh and final data release of the Sloan Digital
Sky
Survey, and is designed to complement the distribution of previously
confirmed
SLACS lenses in lens-galaxy mass and in the ratio of Einstein
radius
to optical half-light radius. The observations we propose will
lead
to a combined SLACS sample covering nearly two decades in mass,
with
dense mapping of enclosed mass as a function of radius out to the
half-light
radius and beyond. With this longer mass baseline, we will
extend
our lensing and dynamical analysis of the mass structure and
scaling
relations of ETGs to galaxies of significantly lower mass, and
directly
test for a transition in structural and dark-matter content
trends
at intermediate galaxy mass. The broader mass coverage will also
enable
us to make a direct connection to the structure of well-studied
nearby
ETGs as deduced from dynamical modeling of their line-of-sight
velocity
distribution fields. Finally, the combined sample will allow a
more
conclusive test of the current SLACS result that the intrinsic
scatter
in ETG mass-density structure is not significantly correlated
with
any other galaxy observables. The final SLACS sample at the
conclusion
of this program will comprise approximately 130 lenses with
known
foreground and background redshifts, and is likely to be the
largest
confirmed sample of strong-lens galaxies for many years to come.
ACS/WFC
12381
Lmaging
the Crab Nebula while it is Flaring in Gamma-rays
The
high energy gamma-ray flux from the Crab nebula doubled in a couple
of
days (from September 19 to September 21). Such enhancement, never
seen
before, is clearly detected both by Agile and Fermi, the two
gamma-ray
telescopes currently in operation. While such huge brightening
is
exciting the entire astrophysical community, TOOs are being scheduled
by
high energy space observatories such as Integral, Swift and Chandra.
By
imaging the status of the knots and wisps in the inner Crab nebula,
HST
could provide a unique piece of information, which may yield a clue
to
understand the source behavior.
ACS/WFC/WFC3/UV
12213
The
Stellar Halo Profiles of Massive Disk Galaxies
Stellar
halos surrounding massive galaxies are of prime interest in
hierarchical
galaxy formation models: most of the halo is formed by the
very
early accretion of small, metal poor satellite galaxies each with
their
independent evolution history. As such, halos contain the fossil
remnants
of the earliest star formation and accretion phases of a galaxy
in
formation. The resulting size, shape, age, and metallicity of stellar
halos
provide therefore a direct test of the basic ingredients
(reionization,
feedback from star formation, density fluctuation power
spectrum)
of hierarchical galaxy formation models.
In
our GHOSTS survey we have sampled the principle axes of a sample of
11
nearby galaxies with Vrot>100 km/s. Our detection of resolved stellar
halo
populations ~1.5 mag below the tip of the Red Giant Branch has
revealed
halos that extend as far as 30 kpc around the most massive
galaxies
in our sample. Those extended stellar halos seem more compact
than
current model predictions, they have unexpectedly high metallicity
up
to the last detected point, and have a luminosity that is more
closely
related to the bulge luminosity than to the galaxy mass. We
propose
to extend the light profiles of 4 massive galaxies with a range
in
bulge-to-disk ratio to the background limit at ~70 kpc. This will
enable
us to:
-
confirm the stellar halo shape (compactness) and assess with
confidence
any conflict with models using these very extended and
accurate
halo profile characterizations;
-
establish whether stellar envelopes beyond 30 kpc are still
morphologically
connected to inner bulges, or whether a break occurs at
larger
radii revealing a distinct new component;
-
determine whether every massive galaxy has an old, metal-poor halo at
large
radius like the Milky Way and M31; if not, constrain for the first
time
the range of stellar metallicity gradients in extended stellar
halos.
COS/NUV
12041
COS-GTO:
Io Atmosphere/STIS
We
will use six HST orbits with COS to observe the disk-integrated
longitudinal
distribution of Io's atmosphere, and ten HST orbits with
STIS
to provide complementary disk-resolved information at key
locations.
We will use the COS G225M grating to observe four SO2
absorption
bands, which can be used to determine SO2 atmospheric
density.
Disk-integrated 19 micron observations of the atmosphere
indicate
that the anti-Jupiter hemisphere of Io has an atmospheric
density
roughly ten times greater than the Jupiter-facing side (Spencer
et
al. 2005), and mm-wave observations suggest a similar pattern.
However
the infrared and mm-wave observations cannot easily separate
atmospheric
density from atmospheric temperature, so these results are
model-dependent.
Sparse 2100 2300 disk-resolved observations
(McGrath
et al. 2000, Jessup et al. 2004) tell a consistent story, but
do
not cover enough of Io's surface to provide full confirmation of the
long-wavelength
result. We will therefore observe Io's disk-integrated
atmospheric
density at six longitudes, roughly 30, 90, 150, 210, 270,
and
330 W, to confirm the 19 micron results and improve our ability to
model
the 19-micron data. With STIS, we plan disk-resolved 2000-3200
spectroscopy
of Io's SO2 atmosphere. Our observations will target
low-latitude
regions away from active plumes (in contrast to our Cycle
10
observations (Jessup et al. 2004) which targeted the Prometheus
plume),
to look for the effect of plumes on the atmosphere. We will also
look
at the variation of low-latitude atmospheric abundance with terrain
type,
to look for explanations for the large longitudinal variations in
atmospheric
pressure to be studied with COS. Finally, we will look at a
variety
of regions at two different times of day to determine the extent
of
diurnal variations in the atmosphere, which are expected if the
atmosphere
is dominantly supported by frost sublimation.
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
11926
IR
Zero Points
We
will measure and monitor the zeropoints through the IR filters using
observations
of the white dwarf standard stars, GD153, GD71 and GD191B2B
and
the solar analog standard star, P330E. Data will be taken monthly
during
Cycle 17. Observations of the star cluster, NGC 104, are made
twice
to check color transformations. We expect an accuracy of 2% in the
wide
filter zeropoints relative to the HST photometric system, and 5% in
the
medium- and narrow-band filters.
WFC3/IR
12181
The
Atmospheric Structure of Giant Hot Exoplanets
Characterization
of close-in giant exoplanets has proceeded rapidly over
the
past few years, due largely to Spitzer and HST observations in
transiting
systems. Low resolution thermal emission spectra of over two
dozen
planets have been measured by Spitzer, and HST observations of a
few
key planets have indicated unusual molecular abundances via
transmission
spectroscopy. However, current models for the atmospheric
structure
of these worlds exhibit degeneracies wherein different
combinations
of temperature and molecular abundance profiles can fit the
same
Spitzer data for each planet. Fortunately, the advent of the IR
capability
on HST/WFC3 allows us to solve this major problem in
exoplanet
science. We propose to inaugurate a Large HST program that is
scientifically
complementary to Spitzer, Kepler, and CoRoT exoplanet
results.
We
will obtain transmission spectroscopy of the 1.4-micron water band in
a
sample of 13 planets, using the G141 grism on WFC3. Among the abundant
molecules,
only water absorbs at this wavelength, and our measurement of
water
abundance will enable us to break the degeneracies in the Spitzer
results
with minimal model assumptions. We will also use the G141 grism
to
observe secondary eclipses for 7 very hot giant exoplanets at
1.5-microns,
including several bright systems in the Kepler and CoRoT
fields.
The strong temperature sensitivity of the thermal continuum at
1.5-microns
provides high leverage on atmospheric temperature for these
worlds,
again helping to break degeneracies in interpreting the Spitzer
data.
Moreover, our precise eclipse photometry, in combination with
extant
Spitzer data, will enable us to extrapolate the thermal continuum
to
optical wavelengths. Kepler and CoRoT teams will be thereby able to
subtract
the thermal contribution from their increasingly precise
measurements
of optical eclipses, and measure, or place extremely
stringent
limits on, the albedo of these exotic worlds.
WFC3/UV
12215
Searching
for the Missing Low-Mass Companions of Massive Stars
Recent
results on binary companions of massive O stars appear to
indicate
that the distribution of secondary masses is truncated at low
masses.
It thus mimics the distribution of companions of G dwarfs and
also
the Initial Mass Function (IMF), except that it is shifted upward
by
a factor of 20 in mass. These results, if correct, provide a
distribution
of mass ratios that hints at a strong constraint on the
star-formation
process. However, this intriguing result is derived from
a
complex simulation of data which suffer from observational
incompleteness
at the low-mass end.
We
propose a snapshot survey to test this result in a very direct way.
HST
WFC3 images of a sample of the nearest Cepheids (which were formerly
B
stars of ~5 Msun) will search for low-mass companions down to M
dwarfs.
We will confirm any companions as young stars, and thus true
physical
companions, through follow-up Chandra X-ray images. Our survey
will
show clearly whether the companion mass distribution is truncated
at
low masses, but at a mass much higher than that of the IMF or G
dwarfs.
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/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
11914
UVIS
Earth Flats
This
program is an experimental path finder for Cycle 18 calibration.
Visible-wavelength
flat fields will be obtained by observing the dark
side
of the Earth during periods of full moon illumination. The
observations
will consist of full-frame streaked WFC3 UVIS imagery: per
22-
min total exposure time in a single "dark-sky" orbit, we anticipate
collecting
7000 e/pix in F606W or 4500 e/pix in F814W. To achieve
Poisson
S/N > 100 per pixel, we require at least 2 orbits of F606W and 3
orbits
of F814W.
For
UVIS narrowband filters, exposures of 1 sec typically do not
saturate
on the sunlit Earth, so we will take sunlit Earth flats for
three
of the more-commonly used narrowband filters in Cycle 17 plus the
also-popular
long-wavelength quad filters, for which we get four filters
at
once.
Why
not use the Sunlit Earth for the wideband visible-light filters? It
is
too bright in the visible for WFC3 UVIS minimum exposure time of 0.5
sec.
Similarly, for NICMOS the sunlit-Earth is too bright which
saturates
the detector too quickly and/or induces abnormal behaviors
such
as super-shading (Gilmore 1998, NIC 098-011). In the narrowband
visible
and broadband near- UV its not too bright (predictions in Cox et
al.
1987 "Standard Astronomical Sources for HST: 6. Spatially Flat
Fields."
and observations in ACS Program 10050).
Other
possibilities? Cox et al.'s Section II.D addresses many other
possible
sources for flat fields, rejecting them for a variety of
reasons.
A remaining possibility would be the totally eclipsed moon.
Such
eclipses provide approximately 2 hours (1 HST orbit) of opportunity
per
year, so they are too rare to be generically useful. An advantage of
the
moon over the Earth is that the moon subtends less than 0.25 square
degree,
whereas the Earth subtends a steradian or more, so scattered
light
and light potentially leaking around the shutter presents
additional
problems for the Earth. Also, we're unsure if HST can point
180
deg from the Sun.