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Daily Report #4613



 
 
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Old May 19th 08, 01:04 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report #4613

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 images. 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
Neptune 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 Neptune returned to a rather Voyager-like
appearance. 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)


 




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