HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5092
PERIOD
COVERED: 5am May 7 - 5am May 10, 2010 (DOY 127/09:00z-130/09:00z)
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
12270
- REAcq(1,2,1) at 129/19:25:47z took 3 attempts to succeed. the
first two attempts resulted in scan step limit exceeded on FGS1.
Previous GSAcq(1,2,1) at 129/17:58:12z was successful on the first
attempt.
12271
- GSAcq(2,0,2) at 130/06:34:11z failed to RGA control due to scan
step limit exceeded on FGS 2.
Observations affected: Astrometry proposal ID#11704.
COMPLETED
OPS REQUEST:
18855-0
- Null Genslew for proposal 12077 - slot 1 @ 127/1911z
COMPLETED
OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSAcq
28
27
FGS
REAcq
18
18
OBAD
with Maneuver 18
18
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED
WFC3/IR/S/C
12089
Persistence
- Part 2
The
IR detectors on WFC3, like other IR detectors, trap charge when
exposed
to sources near or above the full well of the detector diodes.
This
charge leaks out, producing detectable afterglow images for periods
which
can last for several hours, depending on the amount of over
exposure.
These visits, which consist of tungsten lamp exposures of
varying
durations followed by darks, are intended to provide a better
calibration
of persistence over the full area of the IR detector of
WFC3.
WFC3/UV
12077
Monitoring
the Aftermath of an Asteroid Impact Event
Our
Director's Discretionary program (GO-12053) to image the newly
discovered
object P/2010 A2 executed successfully on 2010 Jan 25 and 29
with
spectacular results. Hubble has apparently borne witness to the
first
detection of a collision in the asteroid belt. Hubble imaging with
the
WFC3 has revealed an object unlike anything ever seen before and
with
details impossible to detect with any other facility. We request 6
more
orbits of Hubble time (1 orbit every 20 days over the next few
months,
until the object enters Hubble's solar exclusion zone in
late-June
2010) to monitor the evolution of this remarkable object and
further
clarify the nature of this event. These observations may usher
in
a new era of searching for and characterizing collisional events
within
the asteroid belt.
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.
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/UVIS
11924
WFC3/UVIS
External and Internal CTE Monitor
CCD
detector Charge Transfer Inefficiency (CTI)-induced losses in
photometry
and astrometry will be measured using observations of the
rich
open cluster NGC6791 and with the EPER (Extended Pixel Edge
Response)
method using tungsten lamp flat field exposures. Although we
do
not expect to see CTE effects at the outset of Cycle 17, this CTE
monitoring
program is the first of a multi-cycle program to monitor and
establish
CTE-induced losses with time. We expect to measure CTE effects
with
a precision comparable to the ACS measurements.
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).
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/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/IR
11838
Completing
a Flux-limited Survey for X-ray Emission from Radio Jets
We
will measure the changing flow speeds, magnetic fields, and energy
fluxes
in well-resolved quasar jets found in our short-exposure Chandra
survey
by combining new, deep Chandra data with radio and optical
imaging.
We will image each jet with sufficient sensitivity to estimate
beaming
factors and magnetic fields in several distinct regions, and so
map
the variations in these parameters down the jets. HST observations
will
help diagnose the role of synchrotron emission in the overall SED,
and
may reveal condensations on scales less than 0.1 arcsec.
FGS
11789
An
Astrometric Calibration of Population II Distance Indicators
In
2002, HST produced a highly precise parallax for RR Lyrae. That
measurement
resulted in an absolute magnitude, M(V)= 0.61+/-0.11, a
useful
result, judged by the over ten refereed citations each year
since.
It is, however, unsatisfactory to have the direct,
parallax-based,
distance scale of Population II variables based on a
single
star. We propose, therefore, to obtain the parallaxes of four
additional
RR Lyrae stars and two Population II Cepheids, or W Vir
stars.
The Population II Cepheids lie with the RR Lyrae stars on a
common
K-band Period-Luminosity relation. Using these parallaxes to
inform
that relationship, we anticipate a zero point error of 0.04
magnitude.
This result should greatly strengthen confidence in the
Population
II distance scale and increase our understanding of RR Lyrae
star
and Pop. II Cepheid astrophysics.
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/IR
11719
A
Calibration Database for Stellar Models of Asymptotic Giant Branch
Stars
Studies
of galaxy formation and evolution rely increasingly on the
interpretation
and modeling of near-infrared observations. At these
wavelengths,
the brightest stars are intermediate mass asymptotic giant
branch
(AGB) stars. These stars can contribute nearly 50% of the
integrated
luminosity at near infrared and even optical wavelengths,
particularly
for the younger stellar populations characteristic of
high-redshift
galaxies (z>1). AGB stars are also significant sources of
dust
and heavy elements. Accurate modeling of AGB stars is therefore of
the
utmost importance.
The
primary limitation facing current models is the lack of useful
calibration
data. Current models are tuned to match the properties of
the
AGB population in the Magellanic Clouds, and thus have only been
calibrated
in a very narrow range of sub-solar metallicities.
Preliminary
observations already suggest that the models are
overestimating
AGB lifetimes by factors of 2-3 at lower metallicities.
At
higher (solar) metallicities, there are no appropriate observations
for
calibrating the models.
We
propose a WFC3/IR SNAP survey of nearby galaxies to create a large
database
of AGB populations spanning the full range of metallicities and
star
formation histories. Because of their intrinsically red colors and
dusty
circumstellar envelopes, tracking the numbers and bolometric
fluxes
of AGB stars requires the NIR observations we propose here. The
resulting
observations of nearby galaxies with deep ACS imaging offer
the
opportunity to obtain large (100-1000's) complete samples of AGB
stars
at a single distance, in systems with well-constrained star
formation
histories and metallicities.
FGS
11704
The
Ages of Globular Clusters and the Population II Distance Scale
Globular
clusters are the oldest objects in the universe whose age can
be
accurately determined. The dominant error in globular cluster age
determinations
is the uncertain Population II distance scale. We propose
to
use FGS 1R to obtain parallaxes with an accuracy of 0.2
milliarcsecond
for 9 main sequence stars with [Fe/H] < -1.5. This will
determine
the absolute magnitude of these stars with accuracies of 0.04
to
0.06mag. This data will be used to determine the distance to 24
metal-poor
globular clusters using main sequence fitting. These
distances
(with errors of 0.05 mag) will be used to determine the ages
of
globular clusters using the luminosity of the subgiant branch as an
age
indicator. This will yield absolute ages with an accuracy of 5%,
about
a factor of two improvement over current estimates. Coupled with
existing
parallaxes for more metal-rich stars, we will be able to
accurately
determine the age for globular clusters over a wide range of
metallicities
in order to study the early formation history of the Milky
Way
and provide an independent estimate of the age of the universe.
The
Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an
absolute
magnitude error less than 0.18 mag which is suitable for use in
main
sequence fitting. Previous attempts at main sequence fitting to
metal-poor
globular clusters have had to rely on theoretical
calibrations
of the color of the main sequence. Our HST parallax program
will
remove this source of possible systematic error and yield distances
to
metal-poor globular clusters which are significantly more accurate
than
possible with the current parallax data. The HST parallax data will
have
errors which are 10 times smaller than the current parallax data.
Using
the HST parallaxes, we will obtain main sequence fitting distances
to
11 globular clusters which contain over 500 RR Lyrae stars. This will
allow
us to calibrate the absolute magnitude of RR Lyrae stars, a
commonly
used Population II distance indicator.
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.
ACS/WFC3
11669
The
Origins of Short Gamma-Ray Bursts
During
the past decade extraordinary progress has been made in
determining
the origin of long- duration gamma-ray bursts. It has been
conclusively
shown that these objects derive from the deaths of massive
stars.
Nonetheless, the origin of their observational cousins,
short-duration
gamma-ray bursts (SGRBs) remains a mystery. While SGRBs
are
widely thought to result from the inspiral of compact binaries, this
is
a conjecture. SGRBs have been found in elliptical galaxies, Abell
Clusters,
star-forming dwarfs and even an edge-on spiral. Whether they
primarily
result from an old population, a young population, or rapid
evolution
of binaries in globular clusters remains open.
Here
we propose to employ two related sets of observations which may
dramatically
advance our understanding of short bursts. The first is a
variant
of a technique that we pioneered and used to great effect in
elucidating
the origins of long-duration bursts. We will examine a
statistical
sample of hosts and measure the degree to which SGRB
locations
trace the red or blue light of their hosts, and thus old or
young
stellar populations. This will allow us to study the demographics
of
the SGRB population in a manner largely free of the distance
dependent
selection effects which have so far bedeviled this field. In
the
second line of attack we will use two targets of opportunity to
obtain
extremely precise positions of up to two nearby bursts -- one on
a
star-forming galaxy and the other on a elliptical. Observation of the
star-formation
galaxy could link at least some bursts directly to a
young
population; however, a discovery in later images of a globular
cluster
at the site of the explosion in an elliptical would provide
revolutionary
evidence that SGRBs are formed from compact binaries.
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/UV/ACS/WFC
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.
STIS/CCD
11634
Probing
the Collimation of Pristine Post-AGB Jets with STIS
The
shaping of planetary and protoplanetary nebulae (PNe and PPNe) is
probably
the most exciting yet least understood problem in the late
evolution
of ~1-8 solar mass stars. An increasing number of astronomers
believe
that fast jet-like winds ejected in the PPN phase are
responsible
for carving out the diverse shapes in the dense envelopes of
the
Asymptotic Giant Branch (AGB) stars. To date, the properties of
these
post-AGB jets have not been characterized and, indeed, their
launching/collimation
mechanism is still subject to controversial
debate.
This is due to the lack of the direct observations probing the
spatio-kinematic
structure of post-AGB winds in the stellar vicinity
(~10e16cm),
which is only possible with HST+STIS.
Recently,
STIS observations have allowed us for the first time the
DIRECT
study of the structure and kinematics of the elusive post-AGB
winds
in one PPN, He3-1475 (Sanchez Contreras & Sahai 2001). Those winds
have
been discovered through H-alpha blue-shifted absorption features in
the
inner 0.3"-0.7" of the nebula. These STIS observations have revealed
an
ultra-fast collimated outflow relatively unaffected by the
interaction
with the AGB wind that is totally hidden in ground-based
spectroscopic
observations and HST images. The discovery of the pristine
ultra-fast
(~2300km/s) jet in He3-1475 is the first observational
confirmation
of the presence of collimated outflows as close as ~10e16cm
from
the central star. Most importantly, the spatio-kinematic structure
of
the ultra-fast jet clearly rules out hydrodynamical collimation alone
and
favors magnetic wind collimation. Therefore, STIS observations
provide
a unique method of probing the structure, kinematics, and
collimation
mechanism of the elusive post-AGB winds. We now propose
similar
observations for a sample of bipolar PPNe with ongoing post-AGB
ejections
in order to investigate the frequency of jets like those in
He3-1475
in other PPNe and elucidate their nature and collimation
mechanism.
The observational characterization of these winds is
indispensable
for understanding this violent and important phase of
post-AGB
evolution.
WFC3/IR
11631
Binary
Brown Dwarfs and the L/T Transition
Brown
dwarfs traverse spectral types M, L and T as their atmospheric
structure
evolves and they cool into oblivion. This SNAPSHOT program
will
obtain WFC3-IR images of 45 nearby late-L and early-T dwarfs to
investigate
the nature of the L/T transition. Recent analyses have
suggested
that a substantial proportion of late-L and early-T dwarfs are
binaries,
comprised of an L dwarf primary and T dwarf secondary. WFC3-IR
observations
will let us quantify this suggestion by expanding coverage
to
a much larger sample, and permitting comparison of the L/T binary
fraction
against ‘normal’ ultracool dwarfs. Only eight L/T binaries are
currently
known, including several that are poorly resolved: we
anticipate
at least doubling the number of resolved systems. The
photometric
characteristics of additional resolved systems will be
crucial
to constraining theoretical models of these late-type ultracool
dwarfs.
Finally, our data will also be eminently suited to searching for
extremely
low luminosity companions, potentially even reaching the Y
dwarf
regime.
WFC3/UVIS
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.
ACS/WFC/WFC3/IR
11624
Black
Hole Superkicks: Lmaging the Site of a Gravitational Wave Recoil
Event
Recent
numerical relativity simulations of coalescing, binary
supermassive
black holes (SMBHs) predict kick velocities as large as
several
thousand km/s due to anisotropic emission of gravitational
waves.
We have recently discovered the best candidate to date for such a
recoiling
SMBH, the quasar SDSS0927+2943. It shows an exceptional
optical
emission-line spectrum with two sets of emission lines; one set
of
very narrow emission lines, and a second set of broad Balmer and
broad
high-ionization forbidden lines which are blueshifted by 2650 km/s
relative
to the narrow emission lines. This is the predicted
spectroscopic
signature of a SMBH recoiling from the core of its host
galaxy,
carrying with it the broad-line gas while leaving behind the
bulk
of the narrow-line gas. We apply for HST imaging in two filters for
two
orbits each in order to confirm the recoil model by detecting the
host
galaxy of the SMBH and measuring the angular offset of the
recoiling
SMBH from the host galaxy core; and determining, if possible,
the
morphology of the host galaxy in order to constrain its merger
history.
Confirmation of the SMBH ejection model for SDSSJ0927+2943 with
HST
will show decisively that kicks large enough to remove SMBHs
completely
from their host galaxies do occur, a result that would have
profound
implications for models of SMBH evolution and galaxy assembly
and
for numerical relativity.
WFC3/UV
11602
High-resolution
imaging of three new UV-bright lensed arcs
We
have identified and spectroscopically confirmed three new strongly
lensed,
UV-bright star-forming galaxies at z ~ 2 that are similar to the
well-studied
gravitationally lensed Lyman Break Galaxy (LBG)
MS1512-cB58,
and are of comparable brightness to the ''8 O'Clock Arc''
(Allam
et al. 2007) and ''Clone'' systems (Lin et al. 2008). The 8
O'Clock
Arc and Clone have already been awarded 20 orbits for deep WFPC2
and
NICMOS imaging in five bands (HST cycle 16, Program 11167, PI:
Allam).
Adding these three recently discovered objects thus completes a
unique
set of the brightest known strongly lensed galaxies at z ~ 2,
with
magnitudes of r~20-21, and they provide a new window into the
detailed
study of the properties of high redshift galaxies. We propose
21
orbits for deep WFC3 imaging in five bands (F475W, F606W, F814W,
F110W,
and F160W) in order to construct detailed lensing models, to
probe
the mass and light profiles of the lensing galaxies and their
environments,
and to constrain the spectral energy distributions, star
formation
histories, and morphologies of the lensed galaxies.
STIS/CCD/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.