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Daily Report #5039



 
 
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Old February 24th 10, 04:56 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #5039

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 6.5z8. 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)


 




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