HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5039
PERIOD
COVERED: 5am February 23 - 5am February 24, 2010 (DOY 054/10:00z-055/10:00z)
OBSERVATIONS
SCHEDULED
COS/NUV/FUV
11522
COS-GTO:
Star Formation/Lyman-Alpha
A
sample of 20 star-forming galaxies will be observed with COS G130M.
The
galaxies were selected from the Kitt Peak International
Spectroscopic
Survey (KISSR) data release and cover a broad range of
luminosity,
oxygen abundance, and reddening. The goal of the program is
to
characterize the Lyman-alpha properties and establish correlations
with
fundamental galaxy properties. Each galaxy will be observed for one
orbit.
COS/NUV/FUV
11698
The
Structure and Dynamics of Virgo's Multi-Phase Intracluster Medium
The
dynamical flows of the intracluster medium (ICM) are largely
unknown.
We propose to map the spatial and kinematic distribution of the
warm
ICM of the nearby Virgo cluster using the Cosmic Origins
Spectrograph.
15 sightlines at a range of impact parameters within the
virial
radius of the cluster (0.2 - 1.7 Mpc) will be probed for
Lyman-alpha
absorption and the data compared to blind HI, dust and x-ray
surveys
to create a multi-phase map of the cluster's ICM. Absorption
line
sightlines are commonly 40-100 kpc from a galaxy, allowing the flow
of
baryons between galaxies and the ICM to be assessed. The velocity
distribution
of the absorbers will be directly compared to simulations
and
used to constrain the turbulent motions of the ICM. This proposal
will
result in the first map of a cluster's warm ICM and provide
important
tests for our theoretical understanding of cluster formation
and
the treatment of gas cooling in cosmological simulations.
COS/NUV/FUV
11718
The
Stellar Halos of Dwarf Galaxies
The
metal-poor stellar halo is the oldest extended structure in the
Galaxy.
Such halos are thought to form through hierarchical merging, and
contain
stars pulled from accreted subhalos. The diffuse stellar halo
therefore
stores information about the prop reties of the accreted
galaxies
(i.e., their orbits, stellar masses, and metallicities). It is
therefore
unsurprising that stellar halos have become a popular probe of
the
early epoch of galaxy formation.
Almost
all current work on stellar halos has focused on massive
galaxies,
however. We propose to extend the work on stellar halos to
much
lower mass scales, by studying the halos of faint dwarf galaxies.
By
taking halo studies into the dwarf galaxy regime, we can probe
exceptionally
small mass scales for the accreted halos. At these mass
scales
the effects of reionization and supernova feedback have the
largest
impact on the galaxy population. Stellar halos of dwarf galaxies
are
therefore a sensitive probe of the key processes needed to resolve
the
lack of substructure observed at low masses.
We
are requesting two far-field ACS pointings for the three closest
isolated
nearby dwarf irregular galaxies whose inner halos have already
been
mapped with the ACS Nearby Galaxy Survey Treasury. These outer
fields
will allow us to trace the halo out to roughly half the virial
radius,
further than any previous study. We will use the resulting
distribution
of halo stars (1) to unambiguously measure the structure of
the
stellar halo, with minimal contamination from the main galaxy; (2)
to
constrain the flattening of the stellar halo; (3) to measure the
metallicity
of halo stars as a function of radius; (4) to correlate any
changes
in halo profile with changes in metallicity. The resulting data
will
constrain models of halo accretion and the epoch of reionization.
NIC2/WFC3/IR
11548
Infrared
Imaging of Protostars in the Orion A Cloud: The Role of
Environment
in Star Formation
We
propose NICMOS and WFC3/IR observations of a sample of 252 protostars
identified
in the Orion A cloud with the Spitzer Space Telescope. These
observations
will image the scattered light escaping the protostellar
envelopes,
providing information on the shapes of outflow cavities, the
inclinations
of the protostars, and the overall morphologies of the
envelopes.
In addition, we ask for Spitzer time to obtain 55-95 micron
spectra
of 75 of the protostars. Combining these new data with existing
3.6
to 70 micron photometry and forthcoming 5-40 micron spectra measured
with
the Spitzer Space Telescope, we will determine the physical
properties
of the protostars such as envelope density, luminosity,
infall
rate, and outflow cavity opening angle. By examining how these
properties
vary with stellar density (i.e. clusters vs. groups vs.
isolation)
and the properties of the surrounding molecular cloud; we can
directly
measure how the surrounding environment influences protostellar
evolution,
and consequently, the formation of stars and planetary
systems.
Ultimately, this data will guide the development of a theory of
protostellar
evolution.
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/CCD
11844
CCD
Dark Monitor Part 1
The
purpose of this proposal is to monitor the darks for the STIS CCD.
STIS/CCD
11846
CCD
Bias Monitor-Part 1
The
purpose of this proposal is to 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 deg. C to the ambient instrument
temperature
(~ +5 deg. 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.
WFC3/ACS/UVIS
11684
The
First Proper Motion Measurement for M31: Dynamics and Mass of the
Local
Group
We
will perform observations to determine the proper motion of the
Andromeda
galaxy M31, which has been sought for almost a century without
success.
While challenging, this measurement has now become possible due
to
the availability of existing deep ACS/WFC images of several M31
fields.
The requested second epoch images will yield the average shift
of
the M31 stars with respect to compact galaxies in the background. Our
observing
strategy uses six different fields (three primary and three
coordinated
parallel) with two different instruments (ACS and WFC3) to
provide
a maximum handle on possible systematic effects. The expected
result
will be sufficiently accurate to: (a) discriminate between
different
histories for the dynamics of the Local Group; (b) constrain
the
mass distribution of the Local Group; (c) determine the details of
the
expected future merger between M31 and the Milky Way; (d) infer the
past
interaction history between M31 and M33; (e) constrain the internal
proper
motion kinematics of the M31 spheroid, outer disk, and tidal
stream;
and (f) obtain a pilot estimate of the M31 distance through the
method
of rotational parallax.
WFC3/IR
11591
Are
Low-Luminosity Galaxies Responsible for Cosmic Reionization?
Our
group has demonstrated that massive clusters, acting as powerful
cosmic
lenses, can constrain the abundance and properties of
low-luminosity
star-forming sources beyond z~6; such sources are thought
to
be responsible for ending cosmic reionization. The large
magnification
possible in the critical regions of well-constrained
clusters
brings sources into view that lie at or beyond the limits of
conventional
exposures such as the UDF. We have shown that the
combination
of HST and Spitzer is particularly effective in delivering
the
physical properties of these distant sources, constraining their
mass,
age and past star formation history. Indirectly, we therefore gain
a
valuable glimpse to yet earlier epochs. Recognizing the result (and
limitations)
of blank field surveys, we propose a systematic search
through
10 lensing clusters with ACS/F814W and WFC3/[F110W+F160W] (in
conjunction
with existing deep IRAC data). Our goal is to measure with
great
accuracy the luminosity function at z~7 over a range of at least 3
magnitude,
based on the identification of about 50 lensed galaxies at
6.5<z<8.
Our survey will mitigate cosmic variance and extend the search
both
to lower luminosities and, by virtue of the WFC3/IRAC combination,
to
higher redshift. Thanks to the lensing amplification spectroscopic
follow-up
will be possible and make our findings the most robust prior
to
the era of JWST and the ELTs.
WFC3/IR
11666
Chilly
Pairs: A Search for the Latest-type Brown Dwarf Binaries and the
Prototype
Y Dwarf
We
propose to use HST/NICMOS to image a sample of 27 of the nearest (<
20
pc) and lowest luminosity T-type brown dwarfs in order to identify
and
characterize new very low mass binary systems. Only 3 late-type T
dwarf
binaries have been found to date, despite that fact that these
systems
are critical benchmarks for evolutionary and atmospheric models
at
the lowest masses. They are also the most likely systems to harbor Y
dwarf
companions, an as yet unpopulated putative class of very cold (T <
600
K) brown dwarfs. Our proposed program will more than double the
number
of T5-T9 dwarfs imaged at high resolution, with an anticipated
yield
of ~5 new binaries with initial characterization of component
spectral
types. We will be able to probe separations sufficient to
identify
systems suitable for astrometric orbit and dynamical mass
measurements.
We also expect one of our discoveries to contain the first
Y-type
brown dwarf. Our proposed program complements and augments
ongoing
ground-based adaptive optics surveys and provides pathway
science
for JWST.
WFC3/IR/S/C
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).
WFC3/UVIS
11589
Hypervelocity
Stars as Unique Probes of the Galactic Center and Outer
Halo
We
propose to obtain high-resolution images of 11 new hypervelocity
stars
in the Galactic halo in order to establish the first-epoch
astrometric
frame, as a part of a long-term program to measure precise
proper
motions in an absolute inertial frame. The origin of these
recently
discovered stars with extremely large positive radial
velocities,
in excess of the escape speed from the Galaxy, is consistent
only
with being ejected from the deep potential well of the massive
black
hole at the Galactic center. Reconstructing the full
three-dimensional
space motion of the hypervelocity stars, through
astrometric
proper motions, provides a unique opportunity to measure the
shape
and orientation of the triaxial dark matter halo. The
hypervelocity
stars allow determination of the Galactic potential out to
120
kpc, independently of and at larger distances than is afforded by
tidal
streams of satellite galaxies such as the Sagittarius dSph galaxy.
Proper
motions of the full set of hypervelocity stars will provide
unique
constraints on massive star formation in the environment of the
Galactic
center and on the history of stellar ejection by the
supermassive
black hole. We request one orbit with WFC3 for each of the
11
hypervelocity stars to establish their current positions relative to
background
galaxies. We request a repeated observation of these stars in
Cycle
19, which will conclusively measure the astrometric proper
motions.
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).
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
10
10
FGS
REAcq
7
7
OBAD
with Maneuver 7
7
SIGNIFICANT
EVENTS: (None)