Notice:
Due to the conversion of some ACS WFC or HRC observations into
WFPC2,
or NICMOS observations after the loss of ACS CCD science
capability
in January, there may be an occasional discrepancy between a
proposal's
listed (and correct) instrument usage and the abstract that
follows
it.
HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4463
PERIOD
COVERED: UT October 05,06,07,08, 2007 (DOY 278,279,280,281)
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
8793
NICMOS
Post-SAA calibration - CR Persistence Part 4
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.
WFPC2
11352
Mass
and distance of the sub-Saturn microlensing planet
OGLE-2007-BLG-349Lb
OGLE-2007-BLG-349Lb
is the seventh planet discovered using gravitational
microlensing,
with planet/star mass ratio 2.8e-4. These microlensing
planets
lie in the cold, outer reaches of their solar systems and are
difficult
to detect by other techniques because of their long periods.
However,
microlensing detections by themselves generally give only the
planet/star
mass ratio, not the absolute planet mass. HST observations
have
yielded host star masses and distances for two previous
microlensing
planets. Here, we propose to apply a proven technique to
measure
the mass and distance of the newest microlensing planet, which
was
discovered only two weeks ago. We will use WFPC2 observations to
unambiguously
determine whether the blended light seen during the event
is
due to the host star (rather than a random interloper) and a
combination
of WFPC2 and NICMOS observations to obtain photometric
estimates
of the mass and distance. Two epochs of observations are
required,
one at high magnification (in the very near future) and the
other
at baseline (but not too late -- to avoid having the lens move
substantially
away from the source).
S/C
11320
NICMOS
Focus Monitoring Cycle 16
This
program is a version of the standard focus sweep used since cycle
7.
It has been modified to go deeper and uses more narrow filters for
improved
focus determination. A new source was added in Cycle 14 in
order
to accommodate 2-gyro mode: the open cluster NGC1850. This source
is
part of the current proposal. The old target, the open cluster
NGC3603,
will be used whenever available and the new target used to fill
the
periods when NGC3603 is not visible. Steps: a) Use refined target
field
positions as determined from cycle 7 calibrations b) Use
MULTIACCUM
sequences of sufficient dynamic range to account for defocus
c)
Do a 17-point focus sweep, +/- 8mm about the PAM mechanical zeropoint
for
each cameras 1 and 2, in 1.0mm steps. For NIC3 we step from -0.5mm
to
-9.5mm relative to mechanical zero, in steps of 1.0mm. d) Use PAM X/Y
tilt
and OTA offset slew compensations refined from previous focus
monitoring/optical
alignment activities
FGS
11295
Trigonometric
Calibration of the Distance Scale for Classical Novae
The
distance scale for classical novae is important for understanding
the
stellar physics of their thermonuclear runaways, their contribution
to
Galactic nucleosynthesis, and their use as extragalactic standard
candles.
Although it is known that there is a relationship between their
absolute
magnitudes at maximum light and their subsequent rates of
decline--the
well-known maximum-magnitude rate-of-decline {MMRD}
relation--it
is difficult to set the zero-point for the MMRD because of
the
very uncertain distances of Galactic novae. We propose to measure
precise
trigonometric parallaxes for the quiescent remnants of the four
nearest
classical novae. We will use the Fine Guidance Sensors, which
are
proven to be capable of measuring parallaxes with errors of ~0.2
mas,
well below what is possible from the ground.
WFPC2
11289
SL2S:
The Strong Lensing Legacy Survey
Recent
systematic surveys of strong galaxy-galaxy lenses {CLASS, SLACS,
GOODS,
etc.} are producing spectacular results for galaxy masses roughly
below
a transition mass M~10^13 Mo. The observed lens properties and
their
evolution up to z~0.2, consistent with numerical simulations, can
be
described by isothermal elliptical potentials. In contrast, modeling
of
giant arcs in X-ray luminous clusters {halo masses M >~10^13 Mo}
favors
NFW mass profiles, suggesting that dark matter halos are not
significantly
affected by baryon cooling. Until recently, lensing
surveys
were neither deep nor extended enough to probe the intermediate
mass
density regime, which is fundamental for understanding the assembly
of
structures. The CFHT Legacy Survey now covers 125 square degrees, and
thus
offers a large reservoir of strong lenses probing a large range of
mass
densities up to z~1. We have extracted a list of 150 strong lenses
using
the most recent CFHTLS data release via automated procedures.
Following
our first SNAPSHOT proposal in cycle 15, we propose to
continue
the Hubble follow-up targeting a larger list of 130 lensing
candidates.
These are intermediate mass range candidates {between
galaxies
and clusters} that are selected in the redshift range of 0.2-1
with
no a priori X-ray selection. The HST resolution is necessary for
confirming
the lensing candidates, accurate modeling of the lenses, and
probing
the total mass concentration in galaxy groups up to z~1 with the
largest
unbiased sample available to date.
WFPC2
11227
The
orbital period for an ultraluminous X-ray source in NGC1313
The
ultraluminous X-ray sources {ULXs} are extragalactic point sources
with
luminosities that exceed the Eddington luminosity for conventional
stellar-mass
black holes by factors of 10 - 100. It has been hotly
debated
whether the ULXs are just common stellar-mass black hole sources
with
beamed emission or whether they are sub-Eddington sources that are
powered
by the long-sought intermediate mass black holes {IMBH}. To
firmly
decide this question, one must obtain dynamical mass measurements
through
photometric and spectroscopic monitoring of the secondaries of
these
system. The crucial first step is to establish the orbital period
of
a ULX, and arguably the best way to achieve this goal is by
monitoring
its ellipsoidal light curve. The extreme ULX NGC1313 X-2
provides
an outstanding target for an orbital period determination
because
its relatively bright optical counterpart {V = 23.5} showed a
15%
variation between two HST observations separated by three months.
This
level of variability is consistent with that expected for a tidally
distorted
secondary star. Here we propose a set of 20 imaging
observations
with HST/WFPC2 to define the orbital period. This would be
the
first photometric measurement of the orbital period of a ULX binary.
Subsequently,
we will propose to obtain spectroscopic observations to
obtain
its radial velocity amplitude and thereby a dynamical estimate of
its
mass.
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
11212
Filling
the Period Gap for Massive Binaries
The
current census of binaries among the massive O-type stars is
seriously
incomplete for systems in the period range from years to
millennia
because the radial velocity variations are too small and the
angular
separations too close for easy detection. Here we propose to
discover
binaries in this observational gap through a Faint Guidance
Sensor
SNAP survey of relatively bright targets listed in the Galactic O
Star
Catalog. Our primary goal is to determine the binary frequency
among
those in the cluster/association, field, and runaway groups. The
results
will help us assess the role of binaries in massive star
formation
and in the processes that lead to the ejection of massive
stars
from their natal clusters. The program will also lead to the
identification
of new, close binaries that will be targets of long term
spectroscopic
and high angular resolution observations to determine
their
masses and distances. The results will also be important for the
interpretation
of the spectra of suspected and newly identified binary
and
multiple systems.
WFPC2
11206
At
the cradle of the Milky Way: Formation of the most massive field disk
galaxies
at z>1
We
propose to obtain 2 orbit WFPC2 F814W images of a sample of the 15
most
massive galaxies found at $1 < z < 1.3$. These were culled from
over
20,000 Keck spectra collected as part of DEEP and are unique among
high
redshift massive galaxy samples in being kinematically selected.
Through
a recent HST NICMOS-2 imaging program {
confirmed
that these galaxies have regular stellar disks, and their
emission
line kinematics are not due to gradients from merging
components.
These potentially very young galaxies are likely precursors
to
massive local disks, assuming no further merging. The proposed WFPC2
and
existing NIC-2 data provide colors, stellar masses, and ages of
bulge
and disk subcomponents, to assess whether old stellar bulges and
disks
are in place at that time or still being built, and constrain
their
formation epochs. Finally, this sample will yield the first
statistically
significant results on the $z > 1$ evolution of the
size-velocity-luminosity
scaling relations, for massive galaxies at
different
wavelengths, and constrain whether this evolution reflects
stellar
mass growth, or passive evolution, of either bulge or disk
components.
WFPC2
11203
A
Search for Circumstellar Disks and Planetary-Mass Companions around
Brown
Dwarfs in Taurus
During
a 1-orbit program in Cycle 14, we used WFPC2 to obtain the first
direct
image of a circumstellar disk around a brown dwarf. These data
have
provided fundamental new constraints on the formation process of
brown
dwarfs and the properties of their disks. To search for additional
direct
detections of disks around brown dwarfs and to search for
planetary-mass
companions to these objects, we propose a WFPC2 survey of
32
brown dwarfs in the Taurus star-forming region.
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
11178
Probing
Solar System History with Orbits, Masses, and Colors of
Transneptunian
Binaries
The
recent discovery of numerous transneptunian binaries {TNBs} opens a
window
into dynamical conditions in the protoplanetary disk where they
formed
as well as the history of subsequent events which sculpted the
outer
Solar System and emplaced them onto their present day heliocentric
orbits.
To date, at least 47 TNBs have been discovered, but only about a
dozen
have had their mutual orbits and separate colors determined,
frustrating
their use to investigate numerous important scientific
questions.
The current shortage of data especially cripples scientific
investigations
requiring statistical comparisons among the ensemble
characteristics.
We propose to obtain sufficient astrometry and
photometry
of 23 TNBs to compute their mutual orbits and system masses
and
to determine separate primary and secondary colors, roughly tripling
the
sample for which this information is known, as well as extending it
to
include systems of two near-equal size bodies. To make the most
efficient
possible use of HST, we will use a
optimally
schedule our observations.
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.
ACS/SBC
WFPC2 11175
UV
Imaging to Determine the Location of Residual Star Formation in
Galaxies
Recently Arrived on the Red Sequence
We
have identified a sample of low-redshift {z = 0.04 - 0.10} galaxies
that
are candidates for recent arrival on the red sequence. They have
red
optical colors indicative of old stellar populations, but blue
UV-optical
colors that could indicate the presence of a small quantity
of
continuing or very recent star formation. However, their spectra lack
the
emission lines that characterize star-forming galaxies. We propose
to
use ACS/SBC to obtain high- resolution imaging of the UV flux in
these
galaxies, in order to determine the spatial distribution of the
last
episode of star formation. WFPC2 imaging will provide B, V, and I
photometry
to measure the main stellar light distribution of the galaxy
for
comparison with the UV imaging, as well as to measure color
gradients
and the distribution of interstellar dust. This detailed
morphological
information will allow us to investigate the hypothesis
that
these galaxies have recently stopped forming stars and to compare
the
observed distribution of the last star formation with predictions
for
several different mechanisms that may quench star formation in
galaxies.
NIC2
11152
Probing
the compact dust disk of a nearby Classical T Tauri Star
BP
Psc is a high Galactic latitude {b = -57}, bright, IRAS source that
generally
has been classified as a T Tauri star but little studied to
date.
We have carried out a multiwavelength ground-based study of this
object
and find that it is most likely a ~10 Myr classical T Tauri star
surrounded
by a gas and dust disk, and less than 100 pc from Earth,
making
it one of the oldest and closest such stars known. Near-IR AO
images
and IR photometry show it is surrounded by an compact {0.2"},
almost-edge-on,
optically thick disk of dust with a wide range of
temperatures.
We propose a multiwavelength polarimetric study of the
compact
disk to support quantitative modeling to recover disk and dust
parameters.
We also propose coronagraphic imaging to search for
larger-scale
dust structures invisible in ground-based images, and
narrowband
imaging of an outflow jet and associated Herbig- Haro objects
to
study their structure and determine a kinematic distance of the
system.
A massive compact disk surrounding an isolated 10 Myr star is a
unique
environment for planet formation, and its proximity to Earth
allows
HST to study it in detail.
ACS/SBC
11151
Evaluating
the Role of Photoevaporation of Protoplanetary Disk Dispersal
Emission
produced by accretion onto the central star leads to
photoevaporation,
which may play a fundamental role in disk dispersal.
Models
of disk photoevaporation by the central star are challenged by
two
potential problems: the emission produced by accretion will be
substantially
weaker for low-mass stars, and photoevaporation must
continue
as accretion slows. Existing FUV spectra of CTTSs are biased to
solar-mass
stars with high accretion rates, and are therefore
insufficient
to address these problems. We propose use HST/ACS SBC
PR130L
to obtain FUV spectra of WTTSs and of CTTSs at low masses and
mass
accretion rates to provide crucial data to evaluate
photoevaporation
models. We will estimate the FUV and EUV luminosities
of
low-mass CTTSs with small mass accretion rates, CTTSs with transition
disks
and slowed accretion, and of magnetically-active WTTSs.
NIC2
11143
NICMOS
imaging of submillimeter galaxies with CO and PAH redshifts
We
propose to obtain F110W and F160W imaging of 10 z~2.4 submillimeter
galaxies
{SMGs} whose optical redshifts have been confirmed by the
detection
of millimeter CO and/or mid-infrared PAH emission. With the
4000A
break falling within/between the two imaging filters, we will be
able
to study these sources' spatially resolved stellar populations
{modulo
extinction} in the rest-frame optical. SMGs' large luminosities
appear
to be due largely to merger-triggered starbursts; high-resolution
NICMOS
imaging will help us understand the stellar masses, mass ratios,
and
other properties of the merger progenitors, valuable information in
the
effort to model the mass assembly history of the universe.
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.
WFPC2
11129
The
Star Formation History of the Fornax Dwarf Spheroidal Galaxy
The
Fornax dwarf spheroidal galaxy is one of the most luminous dwarf
satellites
of the Milky Way. It is unusual in many ways: it hosts 5
globular
clusters, shows some relatively young stars, and has faint
sub-structures
which have been interpreted as signs of recent
interactions.
It is thus of great interest to learn the complete star
formation
history {SFH} of Fornax to establish a link between its
evolutionary
path and the predictions from numerical simulations, as a
test
of our understanding of dwarf galaxy evolution. Yet many questions
remain
open. Is the old stellar population made up of stars formed in a
very
early burst, perhaps before the epoch of reionisation, or the
result
of a more continuous star formation between 13 and 9 Gyr ago ?
How
quickly did Fornax increase its metallicity during its initial
assembly
and during subsequent episodes of star formation ? Are
accretion
episodes required to explain the age-metallicity history of
Fornax
? However, there has never been a comprehensive study of the
global
SFH of the Fornax field based on data of sufficient depth to
unambiguously
measure the age mixture of the stellar populations and
their
spatial variation. We propose to use the WFPC2 to obtain very deep
images
in several fields across the central region of Fornax in order to
reach
the oldest main-sequence turnoffs. The number of fields is
determined
by the need to measure the SFH over different regions with
distinct
kinematics and metallicity. The resolution achievable with HST
is
crucial to answer these questions because, to derive the age
distribution
of the oldest stars, we are interested in I magnitude
differences
of the order 0.2 mag in crowded fields at V=24.5. We will
directly
measure the time variation in star-formation rate over the
entire
galaxy history, from first stars coeval with the Milky Way halo
to
the youngest populations 200 Myr ago. The combination of detailed CMD
analysis
with WFPC2 with our existing metallicity and kinematic
information
will allow us to trace out the early phases of its
evolution.
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
11079
Treasury
Imaging of Star Forming Regions in the Local Group:
Complementing
the GALEX and NOAO Surveys
We
propose to use WFPC2 to image the most interesting star-forming
regions
in the Local Group galaxies, to resolve their young stellar
populations.
We will use a set of filters including F170W, which is
critical
to detect and characterize the most massive stars, to whose hot
temperatures
colors at longer wavelengths are not sensitive. WFPC2's
field
of view ideally matches the typical size of the star-forming
regions,
and its spatial resolution allows us to measure individual
stars,
given the proximity of these galaxies. The resulting H-R diagrams
will
enable studies of star-formation properties in these regions, which
cover
largely differing metallicities {a factor of 17, compared to the
factor
of 4 explored so far} and characteristics. The results will
further
our understanding of the star-formation process, of the
interplay
between massive stars and environment, the properties of dust,
and
will provide the key to interpret integrated measurements of
star-formation
indicators {UV, IR, Halpha} available for several
hundreds
more distant galaxies. Our recent deep surveys of these
galaxies
with GALEX {FUV, NUV} and ground-based imaging {UBVRI, Halpha,
[OIII]
and [SII]} provided the identification of the most relevant SF
sites.
In addition to our scientific analysis, we will provide catalogs
of
HST photometry in 6 bands, matched corollary ground-based data, and
UV,
Halpha and IR integrated measurements of the associations, for
comparison
of integrated star-formation indices to the resolved
populations.
We envisage an EPO component.
WFPC2
11029
WFPC2
CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly
Monitor
Intflat
observations will be taken to provide a linearity check: the
linearity
test consists of a series of intflats in F555W, in each gain
and
each shutter. A combination of intflats, visflats, and earthflats
will
be used to check the repeatability of filter wheel motions.
{Intflat
sequences tied to decons, visits 1-18 in prop 10363, have been
moved
to the cycle 15 decon proposal xxxx for easier scheduling.} Note:
long-exposure
WFPC2 intflats must be scheduled during ACS anneals to
prevent
stray light from the WFPC2 lamps from contaminating long ACS
external
exposures.
WFPC2
11024
WFPC2
CYCLE 15 INTERNAL MONITOR
This
calibration proposal is the Cycle 15 routine internal monitor for
WFPC2,
to be run weekly to monitor the health of the cameras. A variety
of
internal exposures are obtained in order to provide a monitor of the
integrity
of the CCD camera electronics in both bays {both gain 7 and
gain
15 -- to test stability of gains and bias levels}, a test for
quantum
efficiency in the CCDs, and a monitor for possible buildup of
contaminants
on the CCD windows. These also provide raw data for
generating
annual super-bias reference files for the calibration
pipeline.
WFPC2
11023
WFPC2
CYCLE 15 Standard Darks - part 1
This
dark calibration program obtains dark frames every week in order to
provide
data for the ongoing calibration of the CCD dark current rate,
and
to monitor and characterize the evolution of hot pixels. Over an
extended
period these data will also provide a monitor of radiation
damage
to the CCDs.
FGS
10929
Calibrating
the Mass-Luminosity Relation at the End of the Main Sequence
We
propose to use HST-FGS1R to finish calibrating the mass-luminosity
relation
for stars less massive than 0.5 Msun, with special emphasis on
objects
near the stellar/substellar border. Our goals are to determine
Mv
values to 0.05 magnitude and masses to 5%, and thereby build the
fundamental
database of stellar masses that we will use to test
theoretical
models as never before. This program uses the combination of
HST-
FGS3/FGS1R at optical wavelengths, historical infrared speckle
data,
ground-based parallax work, metallicity studies, and radial
velocity
monitoring to examine nearby, subarcsecond binary systems. The
high
precision separation and position angle measurements with
HST-FGS3/FGS1R
{to 1 mas in the separations} for these faint {V = 10-15}
targets
simply cannot be equaled by any ground-based technique. As a
result
of these measurements, we are deriving high quality luminosities
and
masses for the components in the systems, and characterizing their
spectral
energy distributions from 0.5 to 2.2 microns. One of the
objects,
GJ 1245 C with mass 0.074 +/- 0.002 Msun, is the only object
known
with an accurate dynamical mass less than 0.10 Msun. The payoff of
this
proposal is high because the six systems selected for final
observations
in Cycles 15 and 16 have already been resolved during
Cycles
5-13 with HST FGS3/FGS1R and contain most of the reddest objects
for
which accurate dynamical masses can be determined.
ACS/SBC
10872
Lyman
Continuum Emission in Galaxies at z=1.2
Lyman
continuum photons produced in massive starbursts may have played a
dominant
role in the reionization of the Universe. Starbursts are
important
contributors to the ionizing metagalactic background at lower
redshifts
as well. However, their contribution to the background depends
upon
the fraction of ionizing radiation that escapes from the intrinsic
opacity
of galaxies below the Lyman limit. Current surveys suggest
escape
fractions of a few percent, up to 10%, with very few detections
{as
opposed to upper limits} having been reported. No detections have
been
reported in the epochs between z=0.1 and z=2. We propose to measure
the
fraction of escaping Lyman continuum radiation from 15 luminous
z~1.2
galaxies in the GOODS fields. Using the tremendous sensitivity of
the
ACS Solar- blind Channel, we will reach AB=30 mag., allowing us to
detect
an escape fraction of 1%. We will correlate the amount of
escaping
radiation with the photometric and morphological properties of
the
galaxies. A non-detection in all sources would imply that QSOs
provide
the overwhelming majority of ionizing radiation at z=1.3, and it
would
strongly indicate that the properties of galaxies at higher
redshift
have to be significantly different for galaxies to dominate
reionization.
The deep FUV images will also be useful for extending the
FUV
study of other galaxies in the GOODS fields.
ACS/SBC
10864
Mapping
the Gaseous Content of Protoplanetary and Young Planetary
Systems
with ACS
One
of the key problems in planetary system formation is understanding
how
rapidly, and over what time interval Jovian planets can form. Dust
in
the protoplanetary disk is critical in planetesimal formation, but it
is
the gas which produces giant planets, and which is essential for
their
migration. However, compared to data on the circumstellar dust,
information
on the gas component is sparse, especially in the
planet-formation
zone. This severely limits our ability to put
observational
constraints on giant planet formation, except to note that
the
process must be largely complete by 12 Myr, given the paucity of
Herbig
Ae or classical T Tauri stars older than 10-12 Myr. In the FUV,
photo-excited
molecular hydrogen transitions have the requisite contrast
to
the stellar photosphere, accretion shock, and reflection nebulosity,
and
can be traced 50-100 AU from the exciting stars in both envelopes
and
outflow cavities and protoplanetary disks. Central disk cavities, an
expected
consequence of planet formation, larger than 0.1" are directly
detectable
in HST FUV spectra, while smaller cavities may be detected by
comparison
with protoplanetary disks which are still accreting onto
their
stars. We propose augmenting existing HST coronagraphic imagery of
6
Herbig Fe and T Tauri disks with ACS Solar-Blind Channel Lyman alpha
imagery
and slitless spectroscopy simultaneously sampling the disk in
molecular
hydrogen and small-grain reflection nebulosity. These data
will
be used to quantify the amount of vertical stratification in these
disks,
to map the mass-loss geometry from the star, and to determine
whether
removal of molecular material precedes, lags, or is contemporary
with
clearing of the dust.
WFPC2
10798
Dark
Halos and Substructure from Arcs & Einstein Rings
The
surface brightness distribution of extended gravitationally lensed
arcs
and Einstein rings contains super-resolved information about the
lensed
object, and, more excitingly, about the smooth and clumpy mass
distribution
of the lens galaxies. The source and lens information can
non-parametrically
be separated, resulting in a direct "gravitational
image"
of the inner mass-distribution of cosmologically-distant galaxies
{Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}. With
this goal
in
mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W WFC
imaging
of 20 new gravitational-lens systems with spatially resolved
lensed
sources, of the 35 new lens systems discovered by the Sloan Lens
ACS
Survey {Bolton et al. 2005} so far, 15 of which are being imaged in
Cycle-14.
Each system has been selected from the SDSS and confirmed in
two
time- efficient HST-ACS snapshot programs {cycle 13&14}.
High-fidelity
multi-color HST images are required {not delivered by the
420s
snapshots} to isolate these lensed images {properly cleaned,
dithered
and extinction-corrected} from the lens galaxy surface
brightness
distribution, and apply our "gravitational maging" technique.
Our
sample of 35 early-type lens galaxies to date is by far the largest,
still
growing, and most uniformly selected. This minimizes selection
biases
and small-number statistics, compared to smaller, often
serendipitously
discovered, samples. Moreover, using the WFC provides
information
on the field around the lens, higher S/N and a better
understood
PSF, compared with the HRC, and one retains high spatial
resolution
through drizzling. The sample of galaxy mass distributions -
determined
through this method from the arcs and Einstein ring HST
images
- will be studied to: {i} measure the smooth mass distribution of
the
lens galaxies {dark and luminous mass are separated using the HST
images
and the stellar M/L values derived from a joint stellar-dynamical
analysis
of each system}; {ii} quantify statistically and individually
the
incidence of mass-substructure {with or without obvious luminous
counter-
parts such as dwarf galaxies}. Since dark-matter substructure
could
be more prevalent at higher redshift, both results provide a
direct
test of this prediction of the CDM hierarchical
structure-formation
model.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
11013
- GSAcq(1,3,1) failed to RGA Hold (Gyro Control)
The GSAcq(1,3,1) scheduled at 278/12:53:30 - 13:01:34 failed to RGA Hold
due to a Search Radius Limit Exceeded Error on FGS-1. During OBAD2 at
278/12:45:03 attitude correction ESB 1806(T2G_OPEN_LOOP_TIMEOUT) was
received at 278/12:47:14 resulting in unplanned M2G transition at
278/12:47:08. Pre-acq OBAD2 had (RSS) value of 3.38 arcseconds. At
278/12:48:55 Equation F2SOB flagged indicating Stuck-on-Bottom, then
back in bounds at 278/12:49:43. Unable to execute FHST Stuck-on-Bottom
Macro due to OBAD acquisition. One (FGS Coarse Track failed -Search
Radius Limit Exceeded) was received at 278/12:59:46.
11014
- Loss of LOCK
REacq(2,3,3) at 280/09:06:48 was successful. At 09:20:02 REacq(2,3,3)
loss lock. A this time the vehicle was performing a T3 slew. The
scheduled TERM EXP was 10:00:32.
11016
- Early Loss of Lock @281/2022z
HST lost fine lock on FGS 1 and 2 at 21:14:57. P4TAKDAT (Take Data Flag)
went down at that time, causing an ACS 779 Status Buffer Message ("Fold
Mechanism Move Was Blocked") to occur at 21:15:08.
GSACQ(1,2,2) at 20:31:50 was successful but mnemonics FSUBLOL and FGSLOL
underwent a long series of limit violations beginning at 20:36:17. Both
of these are derived mnemonics based on QDFGSWT and P4CNTLST ("ST
Control Status"). P4CNTLST toggled between "RGA Only" and
"FGS/RGA"
frequently from 20:38:01 to 21:14:49. Extracts for all of these
mnemonics are attached.
REACQ(1,2,2) at 22:07:11 failed while vehicle was LOS. Upon AOS at
22:47:15 QF1STOPF and QSTOP flags were set and 4 more ACS 779 messages
were received.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED SUCCESSFUL FAILURE
FGS
GSacq 28 27
FGS
REacq 27 26
OBAD
with Maneuver 110 110
LOSS
of LOCK
2
SIGNIFICANT
EVENTS: (None)