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Daily Report #5131



 
 
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Old July 6th 10, 02:36 PM posted to sci.astro.hubble
Bassford, Lynn
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Posts: 44
Default Daily Report #5131

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5131

PERIOD COVERED: 5am July 2 - 5am July 6, 2010 (DOY 183/09:00z-187/09:00z)

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 27 27
FGS REAcq 32 32
OBAD with Maneuver 20 20

SIGNIFICANT EVENTS: (None)



OBSERVATIONS SCHEDULED:

STIS/CCD 11999

JWST Calibration from a Consistent Absolute Calibration of Spitzer &
Hubble

Recently, Gordon, Bohlin, et al. submitted a successful Spitzer
proposal for cross calibration of HST and Spitzer. The
cross-calibration targets are stars in three categories: WDs, A-stars,
and G-stars. Traditionally, IR flux standards are extrapolations of
stellar models that are tied to absolute fluxes at shorter
wavelengths. HST absolute flux standards are among the best available
with a solid basis that uses pure hydrogen models of hot WD stars for
the SED slopes and is tied to Vega at 5556A via precise Landolt V-band
photometry. Consistently matching models to our three categories of
HST observations along with Spitzer photometry and the few existing
absolute IR flux determinations will provide a solid basis for JWST
flux calibration over its 0.8-30micron range. The goal of this
proposal is to complete the HST observations of the set of HST/Spitzer
cross-calibration stars. Using a variety of standard stars with three
different spectral types will ensure that the final calibration is not
significantly affected by systematic uncertainties.

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.

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/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 11915

IR Internal Flat Fields

This program is the same as 11433 (SMOV) and depends on the completion
of the IR initial alignment (Program 11425). This version contains
three instances of 37 internal orbits: to be scheduled early, middle,
and near the end of Cycle 17, in order to use the entire 110-orbit
allocation.

In this test, we will study the stability and structure of the IR
channel flat field images through all filter elements in the WFC3-IR
channel. Flats will be monitored, i.e. to capture any temporal trends
in the flat fields and delta flats produced. High signal observations
will provide a map of the pixel-to-pixel flat field structure, as well
as identify the positions of any dust particles.

WFC3/UVIS 11911

UVIS L-Flats and Geometric Distortion

Multiple pointing observations of the globular cluster Omega Centauri
(NGC 5139) will be used to measure the filter-dependent low frequency
flat field (L-flat) corrections and stability for a key set of 10
broadband filters used by GO programs. The selected filters are F225W,
F275W, F336W, F390W, F438W, F555W, F606W, F775W, F814W and F850LP. By
measuring relative changes in brightness of a star over different
portions of the detector, we will determine local variations in the
UVIS detector response.

The broad wavelength range covered by these observations will allow us
to derive the L-flat correction for the remaining wide, medium and
narrow-band UVIS filters. The same data will also be used to determine
and correct the geometric distortion that affects UVIS data. The broad
wavelength range covered by these observations will allow us to
measure the geometric distortion dependence with wavelength and
filters and to provide the most appropriate correction over the entire
wavelength range provided by UVIS.

WFC3/UVIS 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.

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).

COS/FUV 11897

FUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity in each FUV
grating mode to detect any changes due to contamination or other
causes.

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/NUV 11894

NUV Detector Dark Monitor

The purpose of this proposal is to 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.

ACS/SBC 11886

UV Contamination Monitor

The observations consist of imaging and spectroscopy with SBC and HRC
of the cluster NGC 6681 in order to monitor the temporal evolution of
the UV sensitivity of the SBC and the HRC.

WFC3/ACS/UVIS 11877

HST Cycle 17 and Post-SM4 Optical Monitor

This program is the Cycle 17 implementation of the HST Optical
Monitoring Program.

The 36 orbits comprising this proposal will utilize ACS (Wide Field
Channel) and WFC3 (UVIS Channel) to observe stellar cluster members in
parallel with multiple exposures over an orbit. Phase retrieval
performed on the PSF in each image will be used to measure primarily
focus, with the ability to explore apparent coma, and astigmatism
changes in WFC3.

The goals of this program are to: 1) monitor the overall OTA focal
length for the purposes of maintaining focus within science tolerances
2) gain experience with the relative effectiveness of phase retrieval
on WFC3/UVIS PSFs 3) determine focus offset between the imagers and
identify any SI-specific focus behavior and dependencies

If need is determined, future visits will be modified to interleave
WFC3/IR channel and STIS/CCD focii measurements.

STIS/CCD 11855

STIS/CCD Spectroscopic Sensitivity Monitor for Cycle 17

Monitor sensitivity of each CCD grating mode to detect any change due
to contamination or other causes.

STIS/CC 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/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

WFC3/UV/ACS/WFC 11739

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).

WFC3/UVIS 11732

The Temperature Profiles of Quasar Accretion Disks

We can now routinely measure the size of quasar accretion disks using
gravitational microlensing of lensed quasars. At optical wavelengths
we observe a size and scaling with black hole mass roughly consistent
with thin disk theory but the sizes are larger than expected from the
observed optical fluxes. One solution would be to use a flatter
temperature profile, which we can study by measuring the wavelength
dependence of the disk size over the largest possible wavelength
baseline. Thus, to understand the size discrepancy and to probe closer
to the inner edge of the disk we need to extend our measurements to UV
wavelengths, and this can only be done with HST. For example, in the
UV we should see significant changes in the optical/UV size ratio with
black hole mass. We propose monitoring 5 lenses spanning a broad range
of black hole masses with well-sampled ground based light curves,
optical disk size measurements and known GALEX UV fluxes during Cycles
17 and 18 to expand from our current sample of two lenses. We would
obtain 5 observations of each target in each Cycle, similar to our
successful strategy for the first two targets.

WFC3/UV/ACS/WFC 11710

The Extreme Globular Cluster System of Abell 1689: The Ultimate Test
of Universal Formation Efficiency

The stellar masses of the most luminous galaxies poorly represent the
masses of the halos in which they reside. However, recent studies of
the very rich globular cluster (GC) populations in the centers of
galaxy clusters point toward an apparently linear scaling of the
number of GCs with the total core mass of the galaxy cluster. Thus,
unlike for the stars in cD galaxies, GC formation in these systems
appears to have proceeded with a roughly universal mass conversion
efficiency. GCs are also distinct in that their spatial distributions
are more extended than the starlight, and recent simulations suggest
that they follow the mass density profile of the merged dark matter
halos that formed stars at high redshift. To provide a definitive test
of the universal efficiency hypothesis requires measuring the number
of GCs in the most massive galaxy clusters, where the number should be
a factor of 5 or more greater than seen in M87. Likewise, the
relationship between GCs and mass density can only be tested in
systems where the total mass and mass density are well-determined.
Fortunately, the imaging power of HST brings the GC population of
Abell 1689, the most extreme high-mass lensing cluster, into range.
Estimates of the size of the A1689 GC population from available data
suggest an unprecedented 100, 000 GCs, but this number is based on the
tip of the iceberg and is extremely uncertain. We propose to obtain
the first accurate measurement of the number of GCs and their density
profile in this extraordinary system - the most massive and most
distant GC system ever studied - and thus make the ultimate test of
the universal GC formation hypothesis. Our deep I-band image will also
provide a stringent "null-detection" test of several known z7 galaxy
candidates and improve the mass model of the system by increasing the
number of usable lensed background galaxies. Finally, we will take
deep multi-band parallel observations with WFC3/IR to help in
quantifying the abundance of rare faint red objects.

WFC3/IR 11696

Infrared Survey of Star Formation Across Cosmic Time

We propose to use the unique power of WFC3 slitless spectroscopy to
measure the evolution of cosmic star formation from the end of the
reionization epoch at z6 to the close of the galaxy- building era at
z~0.3.Pure parallel observations with the grisms have proven to be
efficient for identifying line emission from galaxies across a broad
range of redshifts. The G102 grism on WFC3 was designed to extend this
capability to search for Ly-alpha emission from the first galaxies.
Using up to 250 orbits of pure parallel WFC3 spectroscopy, we will
observe about 40 deep (4-5 orbit) fields with the combination of G102
and G141, and about 20 shallow (2-3 orbit) fields with G141 alone.

Our primary science goals at the highest redshifts a (1) Detect Lya
in ~100 galaxies with z5.6 and measure the evolution of the Lya
luminosity function, independent of of cosmic variance; 2) Determine
the connection between emission line selected and continuum-break
selected galaxies at these high redshifts, and 3) Search for the
proposed signature of neutral hydrogen absorption at re-ionization. At
intermediate redshifts we will (4) Detect more than 1000 galaxies in
Halpha at 0.5z1.8 to measure the evolution of the
extinction-corrected star formation density across the peak epoch of
star formation. This is over an order-of-magnitude improvement in the
current statistics, from the NICMOS Parallel grism survey. (5) Trace
``cosmic downsizing" from 0.5z2.2; and (6) Estimate the evolution in
reddening and metallicty in star- forming galaxies and measure the
evolution of the Seyfert population. For hundreds of spectra we will
be able to measure one or even two line pair ratios -- in particular,
the Balmer decrement and [OII]/[OIII] are sensitive to gas reddening
and metallicity. As a bonus, the G102 grism offers the possibility of
detecting Lya emission at z=7-8.8.

To identify single-line Lya emitters, we will exploit the wide
0.8--1.9um wavelength coverage of the combined G102+G141 spectra. All
[OII] and [OIII] interlopers detected in G102 will be reliably
separated from true LAEs by the detection of at least one strong line
in the G141 spectrum, without the need for any ancillary data. We
waive all proprietary rights to our data and will make high-level data
products available through the ST/ECF.

WFC3/UVIS 11661

The Black Hole Mass - Bulge Luminosity Relationship for the Nearest
Reverberation-Mapped AGNs

We propose to obtain WFC3 host galaxy images of the eight nearest AGNs
with masses from reverberation mapping, and one star as a PSF model.
These images will allow us to determine with unprecedented accuracy
the bulge luminosities of the host galaxies, a goal which is not
achievable from the ground due to the blurring of the very bright PSF
component under typical, and even very good, seeing conditions.
High-resolution ACS images of the host galaxies of more luminous AGNs
reveal that the black hole mass-bulge luminosity and black hole
mass-bulge mass relationships for AGNs are not well constrained and
arise from what appear to be fundamentally flawed data sets. With the
addition of the images proposed here to our current sample of ACS
images, we will be able to extend our determinations of the black hole
mass- bulge luminosity and black hole mass-bulge mass relationships
for AGNs by an order of magnitude and test our preliminary results for
these fundamentally important relationships against those previously
determined for quiescent galaxies.

WFC3/UVIS/IR 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 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 11615

Hunting for Optical Companions to Binary MSPs in Globular Clusters

Here we present a proposal which exploits the re-newed potential of
HST after the Service Mission 4 for probing the population of binary
Millisecond Pulsars (MSPs) in Globular Clusters. In particular we
intend to: (1) extend the search for optical counterparts in Terzan 5,
by pushing the performance of the WFC3 IR channel to sample the entire
MS extension down to M=0.1 Mo; (2) perform a deep multi-band search of
MSP companions with the WFC3, in 3 clusters (namely NGC6440, M28 and
M5), where recent radio observations have found particularly
interesting objects; (3) derive an accurate radial velocity (with
STIS) of the puzzling optical companion COM6266B recently discovered
by our group, to firmly assess its cluster membership. This program is
the result of a large collaboration among the three major groups (lead
by Freire, Ransom and Possenti) which are performing extensive MSP
search in GCs in the radio bands, and our group which has a large
experience in performing accurate stellar photometry in crowded
environments. This collaboration has produced a number of outstanding
discoveries. In fact, three of the 6 optical counterparts to binary
MSP companions known to date in GCs have been discovered by our group.
The observations here proposed would easily double/triple the existing
sample of known MSP companions, allowing the first meaningful approach
to the study of the formation, evolution and recycling process of
pulsar in GCs. Moreover, since most of binary MSPs in GCs are thought
to form via stellar interactions in the high density core regions, the
determination of the nature of the companion and the incidence of this
collisionally-induced population has a significant impact on our
knowledge of the cluster dynamics. Even more interesting, the study of
the optical companions to NSs in GCs allows one to derive tighter
constraints (than those obtainable for NS binaries in the Galactic
field) on the system properties. This has, in turn, an intrisic
importance for fundamental physics, since it offers the opportunity of
measuring the mass of the NS and hence constraining the equation of
state of matter at the nuclear equilibrium density.

WFC3/UV 11605

Obtaining the Missing Links in the Test of Very Low Mass Evolutionary
Models with HST

We are proposing for spatially resolved ACS+HRC observations of 11
very low mass binaries spanning late-M, L and T spectral types in
order to obtain precise effective temperature measurements for each
component. All of our targets are part of a program in which we are
measuring dynamical masses of very low-mass binaries to an
unprecedented precision of 10% (or better). However, without precise
temperature measurements, the full scientific value of these mass
measurements cannot be realized. Together, mass and temperature
measurements will allow us to distinguish between brown dwarf
evolutionary models that make different assumptions about the interior
and atmospheric structure of these ultra-cool objects. While dynamical
masses can be obtained from the ground in the near-IR, obtaining
precise temperatures require access to optical data which, for these
sub-arcsecond binaries, can only be obtained from space with Hubble.

WFC3/ACS/UVIS 11603

A Comprehensive Study of Dust Formation in Type II Supernovae with
HST, Spitzer, and Gemini

The recent discovery of three extremely bright Type II SNe, (2007it,
2007oc, 2007od) gives us a unique opportunity to combine observations
with HST, Spitzer, and Gemini to study the little understood dust
formation process in Type II Sne. Priority 1 Spitzer Cycle 5 and band
1 Gemini 2008A time has already been approved for this project. Since
late-time Type II Sne are faint and tend to be in crowded fields, we
need the high sensitivity and high spatial resolution of ACS and
NICMOS/NIC2 for these observations. This project is motivated by the
recent detection of large amounts of dust in high redshift galaxies.
The dust in these high-z galaxies must come from young, massive stars
so Type II Sne could be potential sources. The mechanism and the
efficiency of dust condensation in Type II SN ejecta are not well
understood, largely due to the lack of observational data. We plan to
produce a unique dataset, combining spectroscopy and imaging in the
visible, near- and mid-IR covering the key phase, 400-700 days after
maximum when dust is known to form in the SN ejecta. Therefore, we are
proposing for coordinated HST/NOAO observations (HST ACS, NICMOS/NIC2
& Gemini/GMOS and TReCS) which will be combined with our Spitzer Cycle
5 data to study these new bright Sne. The results of this program will
place strong constraints on the formation of dust seen in young high
redshift (z5) galaxies.

COS/NUV/FUV 11598

How Galaxies Acquire their Gas: A Map of Multiphase Accretion and
Feedback in Gaseous Galaxy Halos

We propose to address two of the biggest open questions in galaxy
formation - how galaxies acquire their gas and how they return it to
the IGM - with a concentrated COS survey of diffuse multiphase gas in
the halos of SDSS galaxies at z = 0.15 - 0.35. Our chief science goal
is to establish a basic set of observational facts about the physical
state, metallicity, and kinematics of halo gas, including the sky
covering fraction of hot and cold material, the metallicity of infall
and outflow, and correlations with galaxy stellar mass, type, and
color - all as a function of impact parameter from 10 - 150 kpc.
Theory suggests that the bimodality of galaxy colors, the shape of the
luminosity function, and the mass-metallicity relation are all
influenced at a fundamental level by accretion and feedback, yet these
gas processes are poorly understood and cannot be predicted robustly
from first principles. We lack even a basic observational assessment
of the multiphase gaseous content of galaxy halos on 100 kpc scales,
and we do not know how these processes vary with galaxy properties.
This ignorance is presently one of the key impediments to
understanding galaxy formation in general. We propose to use the
high-resolution gratings G130M and G160M on the Cosmic Origins
Spectrograph to obtain sensitive column density measurements of a
comprehensive suite of multiphase ions in the spectra of 43 z 1 QSOs
lying behind 43 galaxies selected from the Sloan Digital Sky Survey.
In aggregate, these sightlines will constitute a statistically sound
map of the physical state and metallicity of gaseous halos, and
subsets of the data with cuts on galaxy mass, color, and SFR will seek
out predicted variations of gas properties with galaxy properties. Our
interpretation of these data will be aided by state-of-the-art
hydrodynamic simulations of accretion and feedback, in turn providing
information to refine and test such models. We will also use Keck,
MMT, and Magellan (as needed) to obtain optical spectra of the QSOs to
measure cold gas with Mg II, and optical spectra of the galaxies to
measure SFRs and to look for outflows. In addition to our other
science goals, these observations will help place the Milky Way's
population of multiphase, accreting High Velocity Clouds (HVCs) into a
global context by identifying analogous structures around other
galaxies. Our program is designed to make optimal use of the unique
capabilities of COS to address our science goals and also generate a
rich dataset of other absorption-line systems.

WFC3/ACS/IR 11597

Spectroscopy of IR-Selected Galaxy Clusters at 1 z 1.5

We propose to obtain WFC3 G141 and G102 slitless spectroscopy of
galaxy clusters at 1 z 1.5 that were selected from the IRAC survey
of the Bootes NDWFS field. Our IRAC survey contains the largest sample
of spectroscopically confirmed clusters at z 1. The WFC3 grism data
will measure H-alpha to determine SFR, and fit models to the low
resolution continua to determine stellar population histories for the
brighter cluster members, and redshifts for the red galaxies too faint
for ground-based optical spectroscopy.

ACS/WFC3 11586

Exceptional Galactic Halo Globular Clusters and the Second Parameter

We propose to obtain deep ACS-WFC images of six globular clusters
(five of which have no previous HST photometry) that reside in the
Galactic halo, where the second parameter effect is most pronounced.
These globular clusters are among the least studied in the Galaxy and
yet, from the perspective of the second parameter phenomenon, the most
intriguing.

With the best available CMDs only reaching the vicinity of the main
sequence turn off at present, the unique sensitivity and resolution of
ACS-WFC will yield ages of unprecedented precision for these clusters.
These data will provide us with new insight into the stellar
populations present in the outer Galactic halo and the nature of the
second parameter. The second parameter plays a critical role in our
understanding of the formation and evolution of the Galaxy and the
proposed observations will shed new light on this problem and these
exceptional clusters.

ACS/WFC 11582

The Spatial Distribution of Radiation in the Complex ISM of Distant
Ultraluminous Galaxies

A significant fraction of energy emitted by galaxies at redshifts when
their stars were forming most vigorously, and when their blackholes
were growing most powerfully emerges at far-infrared (IR) wavelengths.
The fraction of this energy generated by the most extreme and luminous
objects is also much larger than the equivalent fraction at optical
wavelengths. Many of the most luminous far-IR sources have been
located precisely and unambiguously using deep radio, Spitzer and
optical observations, and have spectroscopic identifications using the
largest ground-based telescopes. Surprisingly, however, the spectra of
most of these heavily dust-enshrouded galaxies show prominent
Lyman-alpha emission. We propose to observe five of the brightest
examples at z~2-3 in re-activated ACS ramp filters, to resolve the
spatial distribution of this line emission on fine kpc scales, in
order to contrast and compare with the underlying ultraviolet (UV)
continuum. Precise spectroscopic redshifts and the unique rest-UV
resolution of HST are both essential to reveal the escape and
generation of Lyman-alpha photons in the dusty ISM of these extreme
galaxies. There is no other way to trace the detailed spatial
distirbution of the most excited gas in a galactic wind, along with
emission from less-massive star-forming galaxies in associated groups.
The targets have available HST-resolution ground-based near-IR AO
imaging and arcsec-scale images in CO from ground-based mm-wave
interferometers, which provide context for spatial structure of
evolved stars and the ISM. The interplay between restframe UV emission
and the ISM in these galaxies has important consequences for
understanding the origin of the prodigous luminosity of these systems,
and for future observations with JWST and ALMA.

ACS/SBC/COS/NUV/FUV 11579

The Difference Between Neutral- and Ionized-Gas Metal Abundances in
Local Star-Forming Galaxies with COS

The metallicity of galaxies and its evolution with redshift is of
paramount importance for understanding galaxy formation. Abundances in
the interstellar medium (ISM) are typically determined using
emission-line spectroscopy of HII regions. However, since HII regions
are associated with recent SF they may not have abundances typical for
the galaxy as a whole. This is true in particular for star-forming
galaxies (SFGs), in which the bulk of the metals may be contained in
the neutral gas. It is therefore important to directly probe the metal
abundances in the neutral gas. This can be done using absorption lines
in the Far UV. We have developed techniques to do this in SFGs, where
the absorption is measured for sightlines toward bright SF regions
within the galaxy itself. We have successfully applied this technique
to a sample of galaxies observed with FUSE. The results have been very
promising, suggesting in I Zw 18 that abundances in the neutral gas
may be up to 0.5 dex lower than in the ionized gas. However, the
interpretation of the FUSE data is complicated by the very large FUSE
aperture (30 arcsec), the modest S/N, and the limited selection of
species available in the FUSE bandpass. The advent of COS on HST now
allows a significant advance in all of these areas. We will therefore
obtain absorption line spectroscopy with G130M in the same sample for
which we already have crude constraints from FUSE. We will obtain
ACS/SBC images to select the few optimal sightlines to target in each
galaxy. The results will be interpreted through line-profile fitting
to determine the metal abundances constrained by the available lines.
The results will provide important new insights into the metallicities
of galaxies, and into outstanding problems at high redshift such as
the observed offset between the metallicities of Lyman Break Galaxies
and Damped Lyman Alpha systems.

WFC3/UV 11556

Investigations of the Pluto System

We propose a set of high SNR observations of the Pluto system that
will provide improved lightcurves, orbits, and photometric properties
of Nix and Hydra. The key photometric result for Nix and Hydra will be
a vastly improved lightcurve shape and rotation period to test if the
objects are in synchronous rotation or not. A second goal of this
program will be to retrieve a new epoch of albedo map for the surface
of Pluto. These observations will also improve masses and in some case
densities for the bodies in the Pluto system.

WFC3/ACS/UVIS 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 a (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?

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