Notice: For the foreseeable future, the daily reports may
contain
apparent discrepancies between some proposal descriptions
and the listed
instrument usage. This is due to the conversion of
previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS
observations
subsequent to the loss of ACS CCD science capability in
late January.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4366
PERIOD COVERED: UT May 18,19,20, 2007 (DOY 138,139,140)
OBSERVATIONS SCHEDULED
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
indvidual
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 10903
Resolving the LMC Microlensing Puzzle: Where are the
Lensing Objects?
We are requesting 12 HST orbits to continue to investigate
the nature of
the population that gives rise to the microlensing seen
towards the LMC.
This proposal builds on the cycle 14 HST program {10583}
and will
complement the study with 12 yet-to-be discovered
microlensing
candidates from Fall 2006. Our SuperMacho project is an
ongoing ground-
based survey on the CTIO 4m that has demonstrated the
ability to detect
LMC microlensing events via frame subtraction. The
combination of high
angular resolution and photometric accuracy with HST will
allow us to 1}
confrim that the detected flux excursions arise from LMC
stars, rather
than background supernovae or AGN, and 2} obtain reliable
baseline flux
measurements for the objects in their unlensed state. This
latter
measurement in important in determining the microlensing
optical depth
towards the LMC.
WFPC2 10896
An Efficient ACS Coronagraphic Survey for Debris Disks
around Nearby
Stars
We propose to finish our Cycle 11 optical survey for
nearby debris disks
using the ACS/HRC coronagraph. Out of 43 orbits originally
proposed for
the survey, 23 orbits were allocated, leading to a survey
of 22 stars,
from which two new debris disks were imaged for the first
time. Our
analysis of the initial survey gives an empirical estimate
for the
detection rate of debris disks relative to heliocentric
distance and
dust optical depth. Our target list for Cycle 15 is now
optimized to
yield more frequent disk detections. Likewise our observing
strategy is
improved to maximize sensitivity per telescope orbit
allocated.
Therefore we present the most efficient survey possible.
The scientific
motivation is to obtain scattered light images of
previously unresolved
debris disks to determine their viewing geometry and
physical
architecture, both of which may characterize the
underlying planetary
system. We choose 25 debris disk targets for which we
predict a
detection rate of 25% ? 5%. Four targets have extrasolar
planets from
which the viewing geometry revealed by a disk detection
will resolve the
v sin{i} ambiguity in the planet masses. These targets
present the
remarkable opportunity of finally seeing a debris disk in
system with
known planets.
NIC1 10889
The Nature of the Halos and Thick Disks of Spiral Galaxies
We propose to resolve the extra-planar stellar populations
of the thick
disks and halos of seven nearby, massive, edge-on galaxies
using ACS,
NICMOS, and WFPC2 in parallel. These observations will
provide accurate
star counts and color-magnitude diagrams 1.5 magnitudes
below the tip of
the Red Giant Branch sampled along the two principal axes
and one
intermediate axis of each galaxy. We will measure the
metallicity
distribution functions and stellar density profiles from
star counts
down to very low average surface brightnesses, equivalent
to ~32 V-mag
per square arcsec. These observations will provide the
definitive HST
study of extra-planar stellar populations of spiral
galaxies. Our
targets cover a range in galaxy mass, luminosity, and
morphology and as
function of these galaxy properties we will provide: - The
first
systematic study of the radial and isophotal shapes of the
diffuse
stellar halos of spiral galaxies - The most detailed
comparative study
to date of thick disk morphologies and stellar populations
- A
comprehensive analysis of halo and thick disk metallicity
distributions
as a function of galaxy type and position within the
galaxy. - A
sensitive search for tidal streams - The first opportunity
to directly
relate globular cluster systems to their field stellar
population We
will use these fossil records of the galaxy assembly
process preserved
in the old stellar populations to test halo and thick disk
formation
models within the hierarchical galaxy formation scheme. We
will test
LambdaCDM predictions on sub-galactic scales, where it is
difficult to
test using CMB and galaxy redshift surveys, and where it
faces its most
serious difficulties.
WFPC2 10877
A Snapshot Survey of the Sites of Recent, Nearby
Supernovae
During the past few years, robotic {or nearly robotic}
searches for
supernovae {SNe}, most notably our Lick Observatory
Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite
nearby
galaxies {cz < 4000 km/s}. Most of the objects were discovered
before
maximum brightness, and have follow-up photometry and
spectroscopy; they
include some of the best-studied SNe to date. We propose
to conduct a
snapshot imaging survey of the sites of some of these
nearby objects, to
obtain late-time photometry that {through the shape of the
light and
color curves} will help reveal the origin of their
lingering energy. The
images will also provide high-resolution information on
the local
environments of SNe that are far superior to what we can
procure from
the ground. For example, we will obtain color-color and
color-magnitude
diagrams of stars in these SN sites, to determine the SN
progenitor
masses and constraints on the reddening. Recovery of the
SNe in the new
HST images will also allow us to actually pinpoint their
progenitor
stars in cases where pre- explosion images exist in the
HST archive.
This proposal is an extension of our successful Cycle 13
snapshot survey
with ACS. It is complementary to our Cycle 15 archival
proposal, which
is a continuation of our long-standing program to use
existing HST
images to glean information about SN environments.
WFPC2 10870
The Ring Plane Crossings of Uranus in 2007
The rings of Uranus turn edge-on to Earth in May and
August 2007. In
between, we will have a rare opportunity to see the unlit
face of the
rings. With the nine optically thick rings essentialy
invisible, we will
observe features and phenomena that are normally lost in
their glare. We
will use this opportunity to search thoroughly for the
embedded
"shepherd" moons long believed to confine the
edges of the rings,
setting a mass limit roughly 10 times smaller than that of
the smallest
shepherd currently known, Cordelia. We will measure the
vertical
thicknesses of the rings and study the faint dust belts only
known to
exist from a single Voyager image. We will also study the
colors of the
newly-discovered faint, outer rings; recent evidence
suggests that one
ring is red and the other blue, implying that each ring is
dominated by
a different set of physical processes. We will employ
near- edge-on
photometry from 2006 and 2007 to derive the particle
filling factor
within the rings, to observe how ring epsilon responds to
the "traffic
jam" as particles pass through its narrowest point,
and to test the
latest models for preserving eccentricities and apse
alignment within
the rings. Moreover, this data set will allow us to
continue monitoring
the motions of the inner moons, which have been found to
show possibly
chaotic orbital variations; by nearly doubling the time
span of the
existing ACS astrometry, the details of the variations
will become much
clearer.
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 preceeds, lags, or
is contemporary
with clearing of the dust.
ACS/SBC 10862
Comprehensive Auroral Imaging of Jupiter and Saturn during
the
International Heliophysical Year
A comprehensive set of observations of the auroral
emissions from
Jupiter and Saturn is proposed for the International
Heliophysical Year
in 2007, a unique period of especially concentrated
measurements of
space physics phenomena throughout the solar system. We
propose to
determine the physical relationship of the various auroral
processes at
Jupiter and Saturn with conditions in the solar wind at
each planet.
This can be accomplished with campaigns of observations,
with a sampling
interval not to exceed one day, covering at least one
solar rotation.
The solar wind plasma density approaching Jupiter will be
measured by
the New Horizons spacecraft, and a separate campaign near
opposition in
May 2007 will determine the effect of large-scale variations
in the
interplanetary magnetic field {IMF} on the Jovian aurora
by
extrapolation from near-Earth solar wind measurements. A
similar Saturn
campaign near opposition in Jan. 2007 will combine
extrapolated solar
wind data with measurements from a wide range of locations
within the
Saturn magnetosphere by Cassini. In the course of making
these
observations, it will be possible to fully map the auroral
footprints of
Io and the other satellites to determine both the local
magnetic field
geometry and the controlling factors in the
electromagnetic interaction
of each satellite with the corotating magnetic field and
plasma density.
Also in the course of making these observations, the
auroral emission
properties will be compared with the properties of the
near-IR
ionospheric emissions {from ground-based observations} and
non thermal
radio emissions, from ground-based observations for
Jupiter?s decametric
radiation and Cassini plasma wave measurements of the
Saturn Kilometric
Radiation {SKR}.
WFPC2 10832
Solving the microlensing puzzle: An HST high-resolution
imaging approach
We propose to use the HST Advanced Camera for Surveys High
Resolution
Channel to obtain high resolution imaging data for 10
bona-fide LMC
microlensing events seen in the original MACHO survey. The
purpose of
this survey will be to assess whether or not the lens and
source stars
have separated enough to be resolved since the original
microlensing
event took place - about a decade has passed since the
original MACHO
survey and the HST WFPC2 follow-up observations of the
microlensing
events. If the components of the lensing event are
resolved, we will
determine the apparent magnitude and color of both the
lens and the
source stars. These data, in combination with Spitzer/IRAC
data and
Magellan near-IR JHK data, will be used to ascertain the
basic
properties of the lens stars. With the majority of the
microlensing
events in the original MACHO survey observed at the
highest spatial
resolution currently possible, we will be able to draw
important
conclusions as to what fraction of these events have
lenses which belong
to some population of dwarf stars in the disk and what
fraction must be
due to lenses in the halo or beyond. These data will
greatly increase
our understanding of the structure of the Galaxy by
characterizing the
stellar population responsible for the gravitational
microlensing.
WFPC2 10800
Kuiper Belt Binaries: Probes of Early Solar System
Evolution
Binaries in the Kuiper Belt are a scientific windfall: in
them we have
relatively fragile test particles which can be used as
tracers of the
early dynamical evolution of the outer Solar System. We
propose to
continue a Snapshot program using the ACS/HRC that has a
demonstrated
discovery potential an order of magnitude higher than the
HST
observations that have already discovered the majority of
known
transneptunian binaries. With this continuation we seek to
reach the
original goals of this project: to accumulate a
sufficiently large
sample in each of the distinct populations collected in
the Kuiper Belt
to be able to measure, with statistical significance, how
the fraction
of binaries varies as a function of their particular
dynamical paths
into the Kuiper Belt. Today's Kuiper Belt bears the
imprints of the
final stages of giant-planet building and migration;
binaries may offer
some of the best preserved evidence of that long-ago era.
WFPC2 10786
Rotational state and composition of Pluto's outer
satellites
We propose an intricate set of observations aimed at
discovering the
rotational state of the newly discovered satellites of
Pluto, S/2005 P1
and S/2005 P2. These observations will indicate if the
satellites are in
synchronous rotation or not. If they are not, then the
observations will
determine the rotational period or provide tight
constraints on the
amplitude. The other primary goal is to extend the
wavelength coverage
of the colors of the surface and allow us to constrain the
surface
compositions of both objects. From these data we will also
be able to
significantly improve the orbits of P1 and P2, improve the
measurement
of the bulk density of Charon, and search for albedo
changes on the
surface of Pluto.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
10817 - GSacq(2,3,2) failed due to search radius limit
exceeded
During LOS GSacq(2,3,2) scheduled at 140/04:31:31 failed due to search
radius limit exceeded on FGS 2. ESB a05 (exceeded search radius limit)
was received. OBAD2 at 04:26:31 showed errors of V1= 38.65, V2=28.45,
V3=40.61, RSS=62.87.
During LOS the REacq(2,3,2) scheduled at 140/06:10:02 also failed due to
search radius limit exceeded on FGS 2.
10818 - GSAcq (1,2,2) failed to RGA Hold (Gyro Control)
At
140/18:15:30 GSAcq (1,2,2) scheduled from 18:12:08-18:19:32 had
failed to RGA Hold (Gyro Control) due to mnemonic QSTOP on FGS 1. At
18:04:26 received one 486 STB message 1805 "FHST Moving Target
Detected".
OBAD #1 RSS: 3054.12
OBAD #2 RSS: 14.96
OBAD MAP: not scheduled
10819 - ACS 779 Fold Mechanism Move was Blocked
At
140/18:20:24 "Fold Mechanism Move Was Blocked P=0, T=38393. This was
the result of the failed GSAcq at 18:12:08 so the TDF was down when the
fold mechanism move to the SBC position was commanded. The move is
blocked and SBC MAMA HV will remain on. The MAMA HV staying on is a new
feature
for ACS FSW CS4.01.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
24
22
FGS REacq
13
12
OBAD with Maneuver
74
74
SIGNIFICANT EVENTS: (None)