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 # 4488
PERIOD
COVERED: UT November , 2007 (DOY 317)
OBSERVATIONS
SCHEDULED
ACS/SBC
11116
Exploring
the Early FUV History of Cool Stars: Transition Regions at 30
Myr
Stellar
magnetic activity derives from the so-called "dynamo," a
hydromagnetic
interplay between overturning plasma motions and
differential
rotation in stars cool enough to support significant
surface
convection zones. The magnetic fields resulting from dynamo
action
are in turn are responsible for a wide range of high-energy
emissions,
including the spectacular outbursts called flares. Dynamo
powered
magnetic activity is not confined solely to stars, but also must
occur,
for example, in accretion disks of all descriptions, and in some
planets.
A great deal is known about magnetic activity in middle-aged G
dwarfs
like our Sun, thanks to its proximity. Less is known, however,
about
the much younger stars, newly emerged from the T-Tauri stage. Yet,
it
is during this phase that they reach the peak of their magnetic
activity,
and subsidiary influences, such as the impact of ionizing
radiation
and strong coronal winds on developing solar systems, also are
maximum.
One of the key missing ingredients in our current understanding
are
measurements of FUV emissions of such stars, to complement the
extensive
collections of coronal {1-10 MK} X-ray measurements,
particularly
from recent ROSAT, Chandra and XMM-Newton surveys. We
propose
to conduct sensitive ACS/SBC prism ultraviolet spectroscopy of
selected
fields in two young {30 Myr} Galactic clusters--IC 2391 and IC
2602--to
inventory the key C IV emission index {~0.1 MK} over a much
larger
and more diverse sample of coeval objects than has been possible
hitherto.
A key question is whether the FUV emissions also suffer the
"saturation"
and "super-saturation" at short rotation periods seen in
coronal
X-rays, or whether they continue to rise in the fastest rotating
stars.
The saturation behavior of the different temperature regimes
holds
important clues to the organization of the surface active regions
on
these very young stars, and should allow us to distinguish among
several
competing models.
WFPC2
10583
Resolving
the LMC Microlensing Puzzle: Where Are the Lensing Objects ?
We
are requesting 32 HST orbits to help ascertain the nature of the
population
that gives rise to the observed set of microlensing events
towards
the LMC. The SuperMACHO project is an ongoing ground-based
survey
on the CTIO 4m that has demonstrated the ability to detect LMC
microlensing
events in real-time via frame subtraction. The improvement
in
angular resolution and photometric accuracy available from HST will
allow
us to 1} confirm that the detected flux excursions arise from LMC
source
stars rather than extended objects {such as for background
supernovae
or AGN}, and 2} obtain reliable baseline flux measurements
for
the objects in their unlensed state. The latter measurement is
important
to resolve degeneracies between the event timescale and
baseline
flux, which will yield a tighter constraint on the microlensing
optical
depth.
WFPC2
10766
A
Deep X-ray Survey of the Small Magellanic Cloud
We request
deep observations of 2 representative fields in the Small
Magellanic
Cloud with Chandra and HST, with the primary goal of measuring
the
luminosity function and space density of X-ray binaries and other
sources
down to an unprecedented faint luminosity limit of 2x10E32
erg/s.
This will be the faintest XLF ever obtained for any galaxy,
including
our own. HST photometry to 24th magnitude in V and I filters
will
identify the sources and provide Fx/Fopt, which will be vital in
quantifying
the LMXB population and in measuring the properties of the
first
coronally active stars ever detected in an external galaxy.
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.
NIC2
10854
Coronagraphic
Imaging of Bright New Spitzer Debris Disks II.
Fifteen
percent of bright main sequence stars possess dusty
circumstellar
debris disks revealed by far-infrared photometry. These
disks
are signposts of planetary systems: collisions among larger,
unseen
parent bodies maintain the observed dust population against
losses
to radiation pressure and P-R drag. Images of debris disks at
optical,
infrared, and millimeter wavelengths have shown central holes,
rings,
radial gaps, warps, and azimuthal asymmetries which indicate the
presence
of planetary mass perturbers. Such images provide unique
insights
into the structure and dynamics of exoplanetary systems.
Relatively
few debris disks have been spatially resolved. Only thirteen
have
ever been resolved at any wavelength, and at wavelengths < 10
microns
{where subarcsec resolution is available}, only ten. Imaging of
many
other debris disk targets has been attempted with various HST
cameras/coronagraphs
and adaptive optics, but without success. The key
property
which renders a debris disk observable in scattered light is
its
dust optical depth. The ten disks imaged so far all have a dust
excess
luminosity >~ 0.01% that of the central star; no disks with
smaller
optical depths have been detected. Most main sequence stars
known
to meet this requirement have already been observed, so future
progress
in debris disk imaging depends on discovering additional stars
with
large infrared excess. The Spitzer Space Telescope offers the best
opportunity
in 20 years to identify new examples of high optical depth
debris
disk systems. We propose to complete ACS coronagraphic imaging
followup
of bright, new debris disks discovered during the first two
years
of the Spitzer mission, by observing three additional targets in
Cycle
15. Our goal is to obtain the first resolved images of these disks
at
~3 AU resolution, define the disk sizes and orientations,and uncover
disk
substructures indicative of planetary perturbations. The results
will
open wider a window into the structure of planetary systems.
NIC2
11157
NICMOS
Imaging Survey of Dusty Debris Around Nearby Stars Across the
Stellar
Mass Spectrum
Association
of planetary systems with dusty debris disks is now quite
secure,
and advances in our understanding of planet formation and
evolution
can be achieved by the identification and characterization of
an
ensemble of debris disks orbiting a range of central stars with
different
masses and ages. Imaging debris disks in starlight scattered
by
dust grains remains technically challenging so that only about a
dozen
systems have thus far been imaged. A further advance in this field
needs
an increased number of imaged debris disks. However, the technical
challege
of such observations, even with the superb combination of HST
and
NICMOS, requires the best targets. Recent HST imaging investigations
of
debris disks were sample-limited not limited by the technology used.
We
performed a search for debris disks from a IRAS/Hipparcos cross
correlation
which involved an exhaustive background contamination check
to
weed out false excess stars. Out of ~140 identified debris disks, we
selected
22 best targets in terms of dust optical depth and disk angular
size.
Our target sample represents the best currently available target
set
in terms of both disk brightness and resolvability. For example, our
targets
have higher dust optical depth, in general, than newly
identified
Spitzer disks. Also, our targets cover a wider range of
central
star ages and masses than previous debris disk surveys. This
will
help us to investigate planetary system formation and evolution
across
the stellar mass spectrum. The technical feasibility of this
program
in two-gyro mode guiding has been proven with on- orbit
calibration
and science observations during HST cycles 13, 14, and 15.
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.
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!
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
11059
– GSAcq (1,2,2) requires multiple attempts to achieve CT-DV
OTA SE review of PTAS processing revealed that GSAcq (1,2,2)
required
multiple attempts to achieve CT DV on FGS1. (This occurred
on day 314
@19:42:53)
11060
- OBAD Failed Identification
Upon acquisition of signal at 17:48:31 two 486 ESB messages were
observed, 1806 ("T2G Open Loop Timeout"), and 1902
"OBAD Failed
Identification".
Dump of ESB messages reveals that these messages occurred at
16:37:38
and 16:38:22, during the first of the two OBADs at 16:35:33,
second OBAD
at 16:43:28 was successful with RSS correction of 1632.73
arcseconds.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL FAILURE TIMES
FGS
GSacq
09
09
FGS
REacq
04 04
OBAD
with Maneuver
26
25
317/16:38z
SIGNIFICANT
EVENTS: (None)