HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5089
PERIOD
COVERED: 5am May 4 - 5am May 5, 2010 (DOY 124/09:00z-125/09:00z)
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/WFC/WFC3/UVI
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.
ACS/WFC/WFC3/UVI
1739
Multiple
Stellar Generations in the Unique Globular Clusters NGC 6388 and NGC 6441
Over
the last few years HST observations have resulted in one of the
most
exciting and unexpected developments in stellar population studies:
the
discovery of multiple generations of stars in several globular
clusters.
The finding of multiple main sequences in the massive clusters
NGC
2808 and Omega Centauri, and multiple subgiant branches in NGC 1851,
M54,
and NGC 6388 has challenged the long-held paradigm that globular
clusters
are simple stellar populations. Even more surprising, given the
spectroscopic
and photometric constraints, the only viable explanation
for
the main sequence splitting appears to be Helium enrichment, up to
an
astonishingly high Y=0.4. The conditions under which certain
globulars
experience the formation of multiple stellar generations
remain
mysterious, and even more so the helium-enrichment phenomenon.
Such
an enrichment has important implications for chemical-enrichment,
star-formation,
and stellar-evolution scenarios, in star clusters and
likely
elsewhere. To properly constrain the multiple main sequence
phenomenon,
it is important to determine its extent among GCs: is it
limited
to Omega Cen and NGC2808, or is it more common? We propose deep
WFC3
optical/IR imaging of NGC 6388 and 6441, the two globular clusters
that
are most likely to host multiple, helium-enriched populations. Our
simulations
of WFC3 performance suggest that we will be able to detect
even
the main sequence splittings caused by small He differences (Delta
Y
<0.03).
ACS/WFC/WFC3/UVI
12020
The
Deepest Stellar X-ray/optical Census of the Bulge
We
have obtained the deepest optical dataset ever taken or planned
towards
the bulge, allowing bulge/disk decomposition down to F606W=23
and
variability monitoring over seven days, diagnostics not available
for
any bulge field observed by Chandra. We propose ACIS-I imaging to
identify
X-ray point sources in this field. This will directly trace a
number
of fundamental yet poorly-constrained parameters of the inner
Milky
Way, for example the spin-down timescale of stars along the disk
and
bulge; the formation history of the bulge and, for the first time,
direct
constraints on the gravitational potential of the inner milky way
through
AGN-enabled absolute proper motions. Our proposed survey will be
an
essential calibrator for other X-ray/optical surveys of the bulge
both
past and planned.
COS/FUV/COS/NUV
11645
HST
COS Observations of the Atmosphere and Airglow/Aurora of Enceladus
Recent
observations from several instruments on the Cassini spacecraft
have
revealed plumes of dust and water from the southern polar region,
and
clearly shown that Enceladus contributes large amounts of plasma to
Saturn?s
magnetosphere. This implies a global thin atmosphere containing
water
and likely other species, and a local region with orders of
magnitude
higher density near the plumes. While water and dust have been
identified
from the plumes, the presence of many other species in the
atmosphere
is possible and not yet ruled out. The identification of all
significant
species in the atmosphere of Enceladus is of key importance
to
speculation about the source of the water plumes, and the
implications
for any form of life at or below the surface. In addition,
modeling
suggests that Enceladus? mass loading region may be comparable
in
extent to Io?s, and interacts strongly with Saturn?s corotating
magnetic
field and plasma. We have recently concluded a search for an
auroral
footprint of Enceladus in HST images, which set a low upper
limit
implying that the magnetospheric interaction is concentrated near
Enceladus,
rather than being communicated along field lines to Saturn?s
ionosphere.
The next step will be to observe the interaction at the
satellite,
and to learn whatever we can about the physics of the release
of
the atmospheric gas. We propose here an exploratory set of spectral
observations
with HST COS to measure the solar reflection spectrum over
a
broad range of UV wavelengths for atmospheric absorption signatures.
This
will at the same time measure the emission spectrum of the
atmosphere
from both the leading and trailing hemispheres ? Enceladus
orbit
apart, as was done in HST STIS observations of Io to study its
interaction
at Jupiter. The higher sensitivity of COS will be needed to
study
the much smaller and relatively weakly-interacting Enceladus, and
the
outcome of these observations will determine the nature of future
studies
of the atmosphere of Enceladus and its plasma interaction with
the
Saturnian magnetosphere.
COS/NUV/S/C
11891
NUV
MAMA Fold Distribution
The
performance of MAMA microchannel plate can be monitored using a MAMA
fold
analysis procedure. The fold analysis provides a measurement of the
distribution
of charge cloud sizes incident upon the anode giving some
measure
of changes in the pulse-height distribution of the MCP and,
therefore,
MCP gain. This proposal executes the same steps as the COS
SMOV
as proposal 13555 (visit 5).
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/STIS/MA2
11568
A
SNAPSHOT Survey of the Local Interstellar
Medium:
New NUV Observations of Stars with Archived FUV Observations
We
propose to obtain high-resolution STIS E230H SNAP observations of
MgII
and FeII interstellar absorption lines toward stars within 100
parsecs
that already have moderate or high-resolution far-UV (FUV),
900-1700
A, observations available in the MAST Archive. Fundamental
properties,
such as temperature, turbulence, ionization, abundances, and
depletions
of gas in the local interstellar medium (LISM) can be
measured
by coupling such observations. Due to the wide spectral range
of
STIS, observations to study nearby stars also contain important data
about
the LISM embedded within their spectra. However, unlocking this
information
from the intrinsically broad and often saturated FUV
absorption
lines of low-mass ions, (DI, CII, NI, OI), requires first
understanding
the kinematic structure of the gas along the line of
sight.
This can be achieved with high resolution spectra of high-mass
ions,
(FeII, MgII), which have narrow absorption lines, and can resolve
each
individual velocity component (interstellar cloud). By obtaining
short
(~10 minute) E230H observations of FeII and MgII, for stars that
already
have moderate or high-resolution FUV spectra, we can increase
the
sample of LISM measurements, and thereby expand our knowledge of the
physical
properties of the gas in our galactic neighborhood. STIS is the
only
instrument capable of obtaining the required high resolution data
now
or in the foreseeable future.
STIS/MA1
11861
MAMA
FUV Flats
This
program will obtain FUV-MAMA observations of the STIS internal
Krypton
lamp to construct an FUV flat applicable to all FUV modes.
STIS/MA2
11857
STIS
Cycle 17 MAMA Dark Monitor
This
proposal monitors the behavior of the dark current in each of the
MAMA
detectors. The basic monitor takes two 1380s ACCUM darks each week
with
each detector. However, starting Oct 5, pairs are only included for
weeks
that the LRP has external MAMA observations planned. The weekly
pairs
of exposures for each detector are linked so that they are taken
at
opposite ends of the same SAA free interval. This pairing of
exposures
will make it easier to separate long and short term temporal
variability
from temperature dependent changes. For both detectors,
additional
blocks of exposures are taken once every six months. These
are
groups of five 1314 s FUV-MAMA TIME-TAG darks or five 3x315 s NUV
ACCUM
darks distributed over a single SAA free interval. This will give
more
information on the brightness of the FUV MAMA dark current as a
function
of the amount of time that the HV has been on, and for the NUV
MAMA
will give a better measure of the short term temperature
dependence.
WFC3/IR/WFC3/UVI
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 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.
WFC3/UVI
11628
Globular
Cluster Candidates for Hosting a Central Black Hole
We
are continuing our study of the dynamical properties of globular
clusters
and we propose to obtain surface brightness profiles for high
concentration
clusters. Our results to date show that the distribution
of
central surface brightness slopes do not conform to standard models.
This
has important implications for how they form and evolve, and
suggest
the possible presence of central intermediate-mass black holes.
From
our previous archival proposals (AR-9542 and AR-10315), we find
that
many high concentration globular clusters do not have flat cores or
steep
central cusps, instead they show weak cusps. Numerical simulations
suggest
that clusters with weak cusps may harbor intermediate-mass black
holes
and we have one confirmation of this connection with omega
Centauri.
This cluster shows a shallow cusp in its surface brightness
profile,
while kinematical measurements suggest the presence of a black
hole
in its center. Our goal is to extend these studies to a sample
containing
85% of the Galactic globular clusters with concentrations
higher
than 1.7 and look for objects departing from isothermal behavior.
The
ACS globular cluster survey (GO-10775) provides enough objects to
have
an excellent coverage of a wide range of galactic clusters, but it
contains
only a couple of the ones with high concentration. The proposed
sample
consists of clusters whose light profile can only be adequately
measured
from space-based imaging. This would take us close to
completeness
for the high concentration cases and therefore provide a
more
complete list of candidates for containing a central black hole.
The
dataset will also be combined with our existing kinematic
measurements
and enhanced with future kinematic studies to perform
detailed
dynamical modeling.
WFC3/UVI
11630
Monitoring
Active Atmospheres on Uranus and Neptune
We
propose Snapshot observations of Uranus and Neptune to monitor
changes
in their atmospheres on time scales of weeks and months, as we
have
been doing for the past seven years. Previous Hubble Space
Telescope
observations (including previous Snapshot programs 8634,
10170,
10534, and 11156), together with near-IR images obtained using
adaptive
optics on the Keck Telescope, reveal both planets to be dynamic
worlds
which change on time scales ranging from hours to (terrestrial)
years.
Uranus equinox occurred in December 2007, and the northern
hemisphere
is becoming fully visible for the first time since the early
1960s.
HST observations during the past several years (Hammel et al.
2005,
Icarus 175, 284 and references therein) have revealed strongly
wavelength-dependent
latitudinal structure, the presence of numerous
visible-wavelength
cloud features in the northern hemisphere, at least
one
very long-lived discrete cloud in the southern hemisphere, and in
2006
the first clearly defined dark spot seen on Uranus. Long-term
ground-based
observations (Lockwood and Jerzekiewicz, 2006, Icarus 180,
442;
Hammel and Lockwood 2007, Icarus 186, 291) reveal seasonal
brightness
changes that seem to demand the appearance of a bright
northern
polar cap within the next few years. Recent HST and Keck
observations
of Neptune (Sromovsky et al. 2003, Icarus 163, 256 and
references
therein) show a general increase in activity at south
temperate
latitudes until 2004, when Neptune returned to a rather
Voyager-like
appearance with discrete bright spots rather than active
latitude
bands. Further Snapshot observations of these two dynamic
planets
will elucidate the nature of long-term changes in their zonal
atmospheric
bands and clarify the processes of formation, evolution, and
dissipation
of discrete albedo features.
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
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.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
12269
- STIS Status Buffer Messages #645, #646 and #556 received
124/22:54:24z-124/22:55:29z
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSAcq
10
10
FGS
REAcq
6
6
OBAD
with Maneuver 7
7
SIGNIFICANT
EVENTS:
Flash
Report
At
124/22:54z, during a STIS MAMA1 monitor HV ramp, two consecutive
event
yellow limits were exceeded. After the second consecutive out of
limit,
the HV was turned off and event flag 2 was set.