HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4613
PERIOD
COVERED: 5am May 16 - 5am May 19, 2008 (DOY 137/0900z-140/0900z)
OBSERVATIONS
SCHEDULED
NIC1/NIC2/NIC3
8795
NICMOS Post-SAA calibration - CR Persistence Part 6
A
new procedure proposed to alleviate the CR-persistence problem of
NICMOS.
Dark frames will be obtained immediately upon exiting the SAA
contour
23, and every time a NICMOS exposure is scheduled within 50
minutes
of coming out of the SAA. The darks will be obtained in parallel
in
all three NICMOS Cameras. The POST-SAA darks will be non-standard
reference
files available to users with a USEAFTER date/time mark. The
keyword
'USEAFTER=date/time' will also be added to the header of each
POST-SAA
DARK frame. The keyword must be populated with the time, in
addition
to the date, because HST crosses the SAA ~8 times per day so
each
POST-SAA DARK will need to have the appropriate time specified, for
users
to identify the ones they need. Both the raw and processed images
will
be archived as POST-SAA DARKSs. Generally we expect that all NICMOS
science/calibration
observations started within 50 minutes of leaving an
SAA
will need such maps to remove the CR persistence from the science i
mages.
Each observation will need its own CRMAP, as different SAA
passages
leave different imprints on the NICMOS detectors.
NIC1/NIC2/NIC3
8794
NICMOS
Post-SAA calibration - CR Persistence Part 5
A
new procedure proposed to alleviate the CR-persistence problem of
NICMOS.
Dark frames will be obtained immediately upon exiting the SAA
contour
23, and every time a NICMOS exposure is scheduled within 50
minutes
of coming out of the SAA. The darks will be obtained in parallel
in
all three NICMOS Cameras. The POST-SAA darks will be non-standard
reference
files available to users with a USEAFTER date/time mark. The
keyword
'USEAFTER=date/time' will also be added to the header of each
POST-SAA
DARK frame. The keyword must be populated with the time, in
addition
to the date, because HST crosses the SAA ~8 times per day so
each
POST-SAA DARK will need to have the appropriate time specified, for
users
to identify the ones they need. Both the raw and processed images
will
be archived as POST-SAA DARKs. Generally we expect that all NICMOS
science/calibration
observations started within 50 minutes of leaving an
SAA
will need such maps to remove the CR persistence from the science
images.
Each observation will need its own CRMAP, as different SAA
passages
leave different imprints on the NICMOS detectors.
WFPC2
11518
Mutual
eclipses of a Kuiper belt-satellite system
Ground-based
observations two weeks ago strongly suggest that the orbit
of
the small inner satellite of 2003 EL61, the 5th largest known dwarf
planet,
is possibly precisely edge-on and thus somewhere in the middle
of
a ~3 year long cycle of mutual eclipses, occultations, and transits.
We
anticipate that with another year of ground-based observation we may
have
sufficient data to accurately predict the times and durations of
these
events, but by then the events may well be over. If events are
indeed
occurring, measurement of the timing and depths of such events
provides
a wealth of precise geometric information for constraining
sizes,
shapes, orbits, and dynamics of the system.
We
propose to obtain 5 quick WFPC2 visits to 2003 EL61 over the ~19 day
orbital
period of the inner satellite to determine a precise orbit and
predict
mutual event times. We will instantly (within ~1 day of the end
of
the observations) make these predictions public to allow the maximum
number
of attempts to collect the data as possible.
ACS/SBC
11517
A
>10000 solar mass black hole
The
X-ray source XMMUJ134736.6+173403 has recently been discovered
serendipitously.
Its X-ray position coincides with two interacting
galaxies,
one of which is a Seyfert II. The X-ray variability and
spectrum
rule out an association with the Seyfert II. Carpano et al.
(2008)
suggest that the source is a foreground quiescent low-mass X-ray
binary
(unrelated to the galaxy-pair). Our recent optical photometry
rules
out such a scenario since the counterpart to the low-mass X-ray
binary
should have been detected. Furthermore, we find an extended
source
in the XMM error circle. Optical spectroscopy shows emission
lines,
such as those found in ULX nebulae, redshifted to the same
redshift
as that of the pair of interacting galaxies. Swift/UVOT
observations
show that the spectrum of the emission nebula is very blue.
If
this emission nebula is indeed associated with the X-ray source it
implies
that the X-ray source is a ULX. We propose here to obtain an
ACS/SBC
image to accurately determine the magnitude and the extend of
the
nebula and to investigate if the ULX/nebula emission can be
responsible
for the observed X-ray emission by extending the SED to
~1300
angstrom.
WFPC2
11498
2008
Passage of Jupiter's Great Red Spot and Oval BA
Jupiter's
largest anticyclonic storm, the Great Red Spot (GRS), drifts
slowly
westward relative to the radio rotation rate of the planet
(System
III W. longitude). In contrast, the next largest storm, Oval BA
(a.k.a.
the Little Red Spot or LRS), drifts slowly eastward. The
relative
drift of the two is approximately 0.5 deg/day, resulting in a
passage
of the storms every two years. The GRS sits at ~22 deg. S
planetographic
latitude, while the LRS resides at ~33 deg. S latitude.
Both
vortices deflect nearby eastward and westward winds jets around
their
periphery, and are somewhat confined to their latitude bands by
the
alternating, and nearly constant, zonal wind field. However, they do
oscillate
slightly in latitude, particularly near the times of a
passage,
in part because the deflected wind jets push to keep the spots
separated.
It is during these passages that the LRS, and its predecessor
white
ovals, is most likely to show changes in size and morphology,
which
are related to the internal wind fields and regulate the vertical
cloud
structure of the vortex. For example, GRS passages in 1998 and
2000
preceded the merger of the three white ovals into the single large
Oval
BA, after the ovals and intervening cyclonic cells were deflected
by
the GRS.
We propose
to study the 2008 passage to look for changes in internal
vortex
winds, nearby zonal winds and vortex upper cloud structure,
particularly
in particle size and opacity, using five orbits of WFPC2
and
two orbits of NICMOS. These data will be combined with a multitude
of
planned ground-based coverage to offer an unprecedented view of a
GRS/Oval
passage, which will give insight on cloud structure, dynamics,
and
possibly even water abundance below the cloud decks (water abundance
governs
the distance of interaction between the two spots). HST is
required
to provide adequate spatial resolution and wavelength coverage
while
observing the passage. The 2008 passage is expected to be
especially
important, as Jupiter underwent a global upheaval in 2007,
with
disturbances near the GRS and LRS. This upheaval began after the
normal
Cycle 16 proposal deadline, raising the priority of these
observations
enough to warrant a request for HST time.
WFPC2
11235
HST
NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies
in
the Local Universe
At
luminosities above 10^11.4 L_sun, the space density of far-infrared
selected
galaxies exceeds that of optically selected galaxies. These
`luminous
infrared galaxies' {LIRGs} are primarily interacting or
merging
disk galaxies undergoing enhanced star formation and Active
Galactic
Nuclei {AGN} activity, possibly triggered as the objects
transform
into massive S0 and elliptical merger remnants. We propose
NICMOS
NIC2 imaging of the nuclear regions of a complete sample of 88
L_IR
> 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised
Bright
Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}.
This
sample is ideal not only in its completeness and sample size, but
also
in the proximity and brightness of the galaxies. The superb
sensitivity
and resolution of NICMOS NIC2 on HST enables a unique
opportunity
to study the detailed structure of the nuclear regions,
where
dust obscuration may mask star clusters, AGN and additional nuclei
from
optical view, with a resolution significantly higher than possible
with
Spitzer IRAC. This survey thus provides a crucial component to our
study
of the dynamics and evolution of IR galaxies presently underway
with
Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88
galaxies.
Imaging will be done with the F160W filter {H-band} to examine
as
a function of both luminosity and merger stage {i} the luminosity and
distribution
of embedded star clusters, {ii} the presence of optically
obscured
AGN and nuclei, {iii} the correlation between the distribution
of
1.6 micron emission and the mid- IR emission as detected by Spitzer
IRAC,
{iv} the evidence of bars or bridges that may funnel fuel into the
nuclear
region, and {v} the ages of star clusters for which photometry
is
available via ACS/WFC observations. The NICMOS data, combined with
the
HST ACS, Spitzer, and GALEX observations of this sample, will result
in
the most comprehensive study of merging and interacting galaxies to
date.
WFPC2
11233
Multiple
Generations of Stars in Massive Galactic Globular Clusters
This
is a follow-up to recent HST imaging of NGC 2808, which discovered
that
its main sequence is triple, with three well-separated parallel
branches
{Fig.~1}. Along with the double MS of Omega Centauri, this
challenges
the long-held paradigm that globular clusters are simple,
single
stellar populations. The cause of this main sequence multiplicity
in
both clusters is likely to be differences in helium abundance, which
could
play a fundamental role in the understanding of stellar
populations.
We propose to image seven more of the most massive globular
clusters,
to examine their main sequences for indications of splitting.
NIC2
11219
Active
Galactic Nuclei in nearby galaxies: a new view of the origin of
the
radio-loud radio-quiet dichotomy?
Using
archival HST and Chandra observations of 34 nearby early-type
galaxies
{drawn from a complete radio selected sample} we have found
evidence
that the radio-loud/radio-quiet dichotomy is directly connected
to
the structure of the inner regions of their host galaxies in the
following
sense: [1] Radio-loud AGN are associated with galaxies with
shallow
cores in their light profiles [2] Radio-quiet AGN are only
hosted
by galaxies with steep cusps. Since the brightness profile is
determined
by the galaxy's evolution, through its merger history, our
results
suggest that the same process sets the AGN flavour. This
provides
us with a novel tool to explore the co-evolution of galaxies
and
supermassive black holes, and it opens a new path to understand the
origin
of the radio-loud/radio-quiet AGN dichotomy. Currently our
analysis
is statistically incomplete as the brightness profile is not
available
for 82 of the 116 targets. Most galaxies were not observed
with
HST, while in some cases the study is obstructed by the presence of
dust
features. We here propose to perform an infrared NICMOS snapshot
survey
of these 82 galaxies. This will enable us to i} test the reality
of the
dichotomic behaviour in a substantially larger sample; ii} extend
the
comparison between radio-loud and radio-quiet AGN to a larger range
of
luminosities.
FGS
11210
The
Architecture of Exoplanetary Systems
Are
all planetary systems coplanar? Concordance cosmogony makes that
prediction.
It is, however, a prediction of extrasolar planetary system
architecture
as yet untested by direct observation for main sequence
stars
other than the Sun. To provide such a test, we propose to carry
out
FGS astrometric studies on four stars hosting seven companions. Our
understanding
of the planet formation process will grow as we match not
only
system architecture, but formed planet mass and true distance from
the
primary with host star characteristics for a wide variety of host
stars
and exoplanet masses. We propose that a series of FGS astrometric
observations
with demonstrated 1 millisecond of arc per-observation
precision
can establish the degree of coplanarity and component true
masses
for four extrasolar systems: HD 202206 {brown dwarf+planet}; HD
128311
{planet+planet}, HD 160691 = mu Arae {planet+planet}, and HD
222404AB
= gamma Cephei {planet+star}. In each case the companion is
identified
as such by assuming that the minimum mass is the actual mass.
For
the last target, a known stellar binary system, the companion orbit
is
stable only if coplanar with the AB binary orbit.
WFPC2/NIC3
11209
Determining
the Structural Parameters of the First Globular Cluster
Found
to Host an Black-Hole X-ray Binary
We recently
published the discovery of the first black hole X-ray binary
in
a globular cluster. This object is located in a bright globular
cluster
around the Virgo elliptical NGC 4472. Here we propose to obtain
HST
PC images of this black- hole hosting globular cluster and a sample
of
other NGC 4472 globulars. We will use these data to determine the
structural
parameters of both the globular cluster known to have a black
hole
and a control sample of other NGC 4472 clusters. This will test
recent
theoretical predictions how black holes affect the structural
parameters
of globular clusters, and more generally will allow for the
first
time constraints on any relationship between the presence of a
black
hole and the surface brightness profiles of globular clusters. The
deep
WFPC2 images outside of the galaxy's central regions will also be
invaluable
for studying how the sizes and luminosity function of
globular
clusters depend on distance from the center of the galaxy, and
thus
address questions about the origin of the size differences between
metal-rich
and metal-poor clusters and the shape of the globular cluster
luminosity
function. In addition, parallel NIC3 images will allow the
optical
to near-infrared colors of NGC 4472 globular cluster to be
determined
over a wide range of galactocentric radii.
WFPC2
11202
The
Structure of Early-type Galaxies: 0.1-100 Effective Radii
The
structure, formation and evolution of early-type galaxies is still
largely
an open problem in cosmology: how does the Universe evolve from
large
linear scales dominated by dark matter to the highly non-linear
scales
of galaxies, where baryons and dark matter both play important,
interacting,
roles? To understand the complex physical processes
involved
in their formation scenario, and why they have the tight
scaling
relations that we observe today {e.g. the Fundamental Plane}, it
is
critically important not only to understand their stellar structure,
but
also their dark-matter distribution from the smallest to the largest
scales.
Over the last three years the SLACS collaboration has developed
a
toolbox to tackle these issues in a unique and encompassing way by
combining
new non-parametric strong lensing techniques, stellar
dynamics,
and most recently weak gravitational lensing, with
high-quality
Hubble Space Telescope imaging and VLT/Keck spectroscopic
data
of early-type lens systems. This allows us to break degeneracies
that
are inherent to each of these techniques separately and probe the
mass
structure of early-type galaxies from 0.1 to 100 effective radii.
The
large dynamic range to which lensing is sensitive allows us both to
probe
the clumpy substructure of these galaxies, as well as their
low-density
outer haloes. These methods have convincingly been
demonstrated,
by our team, using smaller pilot-samples of SLACS lens
systems
with HST data. In this proposal, we request observing time with
WFPC2
and NICMOS to observe 53 strong lens systems from SLACS, to obtain
complete
multi-color imaging for each system. This would bring the total
number
of SLACS lens systems to 87 with completed HST imaging and
effectively
doubles the known number of galaxy-scale strong lenses. The
deep
HST images enable us to fully exploit our new techniques, beat down
low-number
statistics, and probe the structure and evolution of
early-type
galaxies, not only with a uniform data-set an order of
magnitude
larger than what is available now, but also with a fully
coherent
and self-consistent methodological approach!
WFPC2
11176
Location
and the Origin 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. A number of hosts of SGRBs have been identified, and
have
been used by some to argue that SGRBs derive primarily from an
ancient
population {~ 5 Gyr}; however, it is not known whether this
conclusion
more accurately reflects selection biases or astrophysics.
Here
we propose to employ a variant of a technique that we pioneered and
used
to great effect in elucidating the origins of long-duration bursts.
We
will examine the degree to which SGRB locations trace the red or blue
light
of their hosts, and thus old or young stellar populations. This
approach
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, and should give direct insight
into
the age of the SGRB progenitor population.
WFPC2
11156
Monitoring
Active Atmospheres on Uranus and Neptune
We
propose Snapshot observations of Uranus and Neptune to monitor
changes
in their atmospheres on time scales of weeks and months. Uranus
equinox
is only months away, in December 2007. Hubble Space Telescope
observations
during the past several years {Hammel et al. 2005, Icarus
175,
284 and references therein} have revealed strongly wavelength-
dependent
latitudinal structure, the presence of numerous
visible-wavelength
cloud features in the northern hemisphere, at least
one
very long-lived discrete cloud in the southern hemisphere, and in
2006
the first dark spot ever seen on Uranus. Long-term ground-based
observations
{Lockwood and Jerzekiewicz, 2006, Icarus 180, 442; Hammel
and
Lockwood 2007, Icarus 186, 291} reveal seasonal brightness changes
whose
origins are not well understood. Recent near-IR images of
obtained
using adaptive optics on the Keck Telescope, together with HST
observations
{Sromovsky et al. 2003, Icarus 163, 256 and references
therein}
which include previous Snapshot programs {GO 8634, 10170,
10534}
show a general increase in activity at south temperate latitudes
until
2004, when
Further
Snapshot observations of these two dynamic planets will
elucidate
the nature of long-term changes in their zonal atmospheric
bands
and clarify the processes of formation, evolution, and dissipation
of
discrete albedo features.
WFPC2
11134
WFPC2
Tidal Tail Survey: Probing Star Cluster Formation on the Edge
The
spectacular HST images of the interiors of merging galaxies such as
the
Antennae and NGC 7252 have revealed rich and diverse populations of
star
clusters created over the course of the interaction. Intriguingly,
our
WFPC2 study of tidal tails in these and other interacting pairs has
shown
that star cluster birth in the tails does not follow a similarly
straightforward
evolution. In fact, cluster formation in these
relatively
sparse environments is not guaranteed -- only one of six
tails
in our initial study showed evidence for a significant population
of
young star clusters. The tail environment thus offers the opportunity
to
probe star cluster formation on the edge of the physical parameter
space
{e.g., of stellar and gas mass, density, and pressure} that
permits
it to occur. We propose to significantly extend our pilot sample
of
optically bright, gas-rich tidal tails by a factor of 4 in number to
include
a more diverse population of tails, encompassing major and minor
mergers,
gas-rich and gas-poor tails, as well as early, late, and merged
interaction
stages. With 21 orbits of HST WFPC2 imaging in the F606W and
F814W
filters, we can identify, roughly age-date, and measure sizes of
star
clusters to determine what physical parameters affect star cluster
formation.
WFPC2 imaging has been used effectively in our initial study
of
four mergers, and it will be possible in this program to reach
similar
limits of Mv=-8.5 for each of 16 more tails. With the much
larger
sample we expect to isolate which factors, such as merger stage,
HI
content, and merger mass ratio, drive the formation of star clusters.
WFPC2
11130
AGNs
with Intermediate-mass Black Holes: Testing the Black Hole-Bulge
Paradigm,
Part II
The
recent progress in the study of central black holes in galactic
nuclei
has led to a general consensus that supermassive {10^6-10^9 solar
mass}
black holes are closely connected with the formation and
evolutionary
history of large galaxies, especially their bulge
component.
Two outstanding issues, however, remain unresolved. Can
central
black holes form in the absence of a bulge? And does the mass
function
of central black holes extend below 10^6 solar masses?
Intermediate-mass
black holes {<10^6 solar masses}, if they exist, may
offer
important clues to the nature of the seeds of supermassive black
holes.
Using the SDSS, our group has successfully uncovered a new
population
of AGNs with intermediate-mass black holes that reside in
low-luminosity
galaxies. However, very little is known about the
detailed
morphologies or structural parameters of the host galaxies
themselves,
including the crucial question of whether they have bulges
or
not. Surprisingly, the majority of the targets of our Cycle 14 pilot
program
have structural properties similar to dwarf elliptical galaxies.
The
statistics from this initial study, however, are really too sparse
to
reach definitive conclusions on this important new class of black
holes.
We wish to extend this study to a larger sample, by using the
Snapshot
mode to obtain WFPC2 F814W images from a parent sample of 175
AGNs
with intermediate- mass black holes selected from our final SDSS
search.
We are particularly keen to determine whether the hosts contain
bulges,
and if so, how the fundamental plane properties of the host
depend
on the mass of their central black holes. We will also
investigate
the environment of this unique class of AGNs.
NIC3
11120
A
Paschen-Alpha Study of Massive Stars and the ISM in the Galactic
Center
The
Galactic center (GC) is a unique site for a detailed study of a
multitude
of complex astrophysical phenomena, which may be common to
nuclear
regions of many galaxies. Observable at resolutions
unapproachable
in other galaxies, the GC provides an unparalleled
opportunity
to improve our understanding of the interrelationships of
massive
stars, young stellar clusters, warm and hot ionized gases,
molecular
clouds, large scale magnetic fields, and black holes. We
propose
the first large-scale hydrogen Paschen alpha line survey of the
GC
using NICMOS on the Hubble Space Telescope. This survey will lead to
a
high resolution and high sensitivity map of the Paschen alpha line
emission
in addition to a map of foreground extinction, made by
comparing
Paschen alpha to radio emission. This survey of the inner 75
pc
of the Galaxy will provide an unprecedented and complete search for
sites
of massive star formation. In particular, we will be able to (1)
uncover
the distribution of young massive stars in this region, (2)
locate
the surfaces of adjacent molecular clouds, (3) determine
important
physical parameters of the ionized gas, (4) identify compact
and
ultra-compact HII regions throughout the GC. When combined with
existing
Chandra and Spitzer surveys as well as a wealth of other
multi-wavelength
observations, the results will allow us to address such
questions
as where and how massive stars form, how stellar clusters are
disrupted,
how massive stars shape and heat the surrounding medium, and
how
various phases of this medium are interspersed.
WFPC2
11119
The
Stellar Origins of Supernovae
Supernovae
{SNe} have a profound effect on galaxies, and have been used
recently
as precise cosmological probes, resulting in the discovery of
the
accelerating Universe. They are clearly very important events
deserving
of intense study. Yet, even with nearly 4000 known SNe, we
know
relatively little about the stars which give rise to these powerful
explosions.
The main limitation has been the lack of spatial resolution
in
pre-SN imaging data. However, since 1999 our team has been at the
vanguard
of directly identifying SN progenitor stars in HST images. From
this
exciting new line of study, the emerging trend from 5 detections
for
Type II-Plateau SNe is that their progenitors appear to be
relatively
low mass {8 to 20 Msun} red supergiants, although more cases
are
needed. Nonetheless, the nature of the progenitors of Type Ib/c SNe,
a
subset of which are associated with the amazing gamma-ray bursts,
remains
ambiguous. Furthermore, we remain in the continually
embarrassing
situation that we still do not yet know which progenitor
systems
explode as Type Ia SNe, which are currently being used for
precision
cosmology. We propose to confirm the identities of the
progenitors
of 4 SNe within 17 Mpc, which we expect to occur during
Cycle
16, through ToO observations using WFPC2/PC.
NIC1
11117
The
Search for Atmospheric Water in the Transiting Planet HD189733b
We
propose to use the NICMOS camera to search for transit NIR signatures
of
atmospheric water in HD189733b. While water absorption bands exist in
the
optical and IR, space-based NIR signatures are uniquely positioned
to
offer the best chance at detection. Using narrow band photometric
filters,
we will be able to detect absorption signatures while the
planet
is in primary transit. A positive detection would be the first
proof
of water on an extrasolar planet. Furthermore, it would provide
invaluable
planetary information, constraining the entire chemistry. As
a
byproduct of the high SNR required for our primary science goal, we
will
be able to improve on the value of the planetary radius, a result
independent
of our primary science objective. The accurate radius
estimate,
together with planet structure models, will allow constraining
the
planet interior and its relationship with formation models and
stellar
metallicity.
WFPC2
11113
Binaries
in the Kuiper Belt: Probes of Solar System Formation and
Evolution
The
discovery of binaries in the Kuiper Belt and related small body
populations
is powering a revolutionary step forward in the study of
this
remote region. Three quarters of the known binaries in the Kuiper
Belt
have been discovered with HST, most by our snapshot surveys. The
statistics
derived from this work are beginning to yield surprising and
unexpected
results. We have found a strong concentration of binaries
among
low-inclination Classicals, a possible size cutoff to binaries
among
the Centaurs, an apparent preference for nearly equal mass
binaries,
and a strong increase in the number of binaries at small
separations.
We propose to continue this successful program in Cycle 16;
we
expect to discover at least 13 new binary systems, targeted to
subgroups
where these discoveries can have the greatest impact.
NIC3
11107
Imaging
of Local Lyman Break Galaxy Analogs: New Clues to Galaxy
Formation
in the Early Universe
We
have used the ultraviolet all-sky imaging survey currently being
conducted
by the Galaxy Evolution Explorer {GALEX} to identify for the
first
time a rare population of low-redshift starbursts with properties
remarkably
similar to high-redshift Lyman Break Galaxies {LBGs}. These
"compact
UV luminous galaxies" {UVLGs} resemble LBGs in terms of size,
SFR,
surface brightness, mass, metallicity, kinematics, dust, and color.
The
UVLG sample offers the unique opportunity of investigating some very
important
properties of LBGs that have remained virtually inaccessible
at
high redshift: their morphology and the mechanism that drives their
star
formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS
in
order to 1} characterize their morphology and look for signs of
interactions
and mergers, and 2} probe their star formation histories
over
a variety of timescales. The images show a striking trend of small-
scale
mergers turning large amounts of gas into vigorous starbursts {a
process
referred to as dissipational or "wet" merging}. Here, we propose
to
complete our sample of 31 LBG analogs using the ACS/SBC F150LP {FUV}
and
WFPC2 F606W {R} filters in order to create a statistical sample to
study
the mechanism that triggers star formation in UVLGs and its
implications
for the nature of LBGs. Specifically, we will 1} study the
trend
between galaxy merging and SFR in UVLGs, 2} artificially redshift
the
FUV images to z=1-4 and compare morphologies with those in similarly
sized
samples of LBGs at the same rest-frame wavelengths in e.g. GOODS,
UDF,
and COSMOS, 3} determine the presence and morphology of significant
stellar
mass in "pre- burst" stars, and 4} study their immediate
environment.
Together with our Spitzer {IRAC+MIPS}, GALEX, SDSS and
radio
data, the HST observations will form a unique union of data that
may
for the first time shed light on how the earliest major episodes of
star
formation in high redshift galaxies came about. This proposal was
adapted
from an ACS HRC+WFC proposal to meet the new Cycle 16 observing
constraints,
and can be carried out using the ACS/SBC and WFPC2 without
compromising
our original science goals.
WFPC2
11103
A
Snapshot Survey of The Most Massive Clusters of Galaxies
We
propose the continuation of our highly successful SNAPshot survey of
a
sample of 125 very X-ray luminous clusters in the redshift range
0.3-0.7.
As demonstrated by the 25 snapshots obtained so far in Cycle14
and
Cycle15 these systems frequently exhibit strong gravitational
lensing
as well as spectacular examples of violent galaxy interactions.
The
proposed observations will provide important constraints on the
cluster
mass distributions, the physical nature of galaxy-galaxy and
galaxy-gas
interactions in cluster cores, and a set of optically bright,
lensed
galaxies for further 8-10m spectroscopy. All of our primary
science
goals require only the detection and characterization of
high-surface-brightness
features and are thus achievable even at the
reduced
sensitivity of WFPC2. Because of their high redshift and thus
compact
angular scale our target clusters are less adversely affected by
the
smaller field of view of WFPC2 than more nearby systems.
Acknowledging
the broad community interest in this sample we waive our
data
rights for these observations. Due to a clerical error at STScI our
approved
Cycle15 SNAP program was barred from execution for 3 months and
only
6 observations have been performed to date - reinstating this SNAP
at
Cycle16 priority is of paramount importance to reach meaningful
statistics.
WFPC2
10905
The
Dynamic State of the Dwarf Galaxy Rich Canes Venatici I Region
With
accurate distances, the nearest groups of galaxies can be resolved
in
3 dimensions and the radial component of the motions of galaxies due
to
local density perturbations can be distinguished from cosmological
expansion
components. Currently, with the ACS, galaxy distances within 8
Mpc
can be measured effectively and efficiently by detecting the tip of
the
red giant branch {TRGB}. Of four principal groups at high galactic
latitude
in this domain, the Canes Venatici I Group {a} is the least
studied,
{b} is the most populated, though overwhelmingly by dwarf
galaxies,
and {c} is likely the least dynamically evolved. It is
speculated
that galaxies in low mass groups may fail to retain baryons
as
effectively as those in high mass groups, resulting in significantly
higher
mass-to-light ratios. The CVn I Group is suspected to lie in the
mass
regime where the speculated astrophysical processes that affect
baryon
retention are becoming important.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
11310
- GSacq(1,2,1) failed to RGA control
GSacq(1,2,1) scheduled at 139/22:45:38 failed at 22:50:03 due to
search
radius limit exceeded on FGS 1. ESB "a05" Exceeded SRL
was received.
OBAD1 had an RSS value of 4802.35 a-s and OBAD2 had an RSS value
of
41.85 a-s.
11311
- REacq(1,2,1) failed to RGA Control
REacq(1,2,1)scheduled at 140/03:32:02 failed to RGA control due to
search radius limit exceeded on FGS 1. ESB "a05"
Exceeded SRL was
received. OBAD1 showed errors of V1=-428.49, V2=-634.65, V3=219.34
and
RSS = 796.55. OBAD2 showed errors of V1=-45.94, V2=-26.59,
V3=-63.00,
and RSS=82.38.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
27
26
FGS
REacq
16
15
OBAD
with Maneuver
86
86
SIGNIFICANT
EVENTS: (None)