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 # 4389
PERIOD COVERED: UT June 21, 2007 (DOY 172)
OBSERVATIONS SCHEDULED
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.
ACS/SBC 10810
The Gas Dissipation Timescale: Constraining Models of
Planet Formation
We propose to constrain planet-formation models by
searching for
molecular hydrogen emission around young {10-50 Myr}
solar-type stars
that have evidence for evolved dust disks. Planet
formation models show
that the presence of gas in disks is crucial to the
formation of BOTH
giant and terrestrial planets, influences dust dynamics,
and through
tidal interactions with giant planets leads to orbital
migration.
However, there is a lack of systematic information on the
presence and
lifetime of gas residing at planet-forming radii. We will
use a newly
identified broad continuum emission feature of molecular
hydrogen at
1600 Angstrom to search for residual gas within an orbital
radius of
5-10 AU around young stars that have evolved beyond the optically
thick
T Tauri phase. These observations will enable the most
sensitive probe
to date of remant gas in circumstellar disks, detecting
surfaces
densites of ~0.0001 g/cm^2, or less than 10^-5 of the
theoretical
"mininum mass" solar nebula from which our solar
system is thought to
have formed. Our observations are designed to be
synergistic with
ongoing searches for gas emission that is being performed
using the
Spitzer Space Telescope in that the proposed HST
observations are ~100
times more sensitive and will have 50 times higher angular
resolution.
These combined studies will provide the most comprehensive
view of
residual gas in proto-planetary disks and can set
important constraints
on models of planet formation.
WFPC2 10886
The Sloan Lens ACS Survey: Towards 100 New Strong Lenses
As a continuation of the highly successful Sloan Lens ACS
{SLACS} Survey
for new strong gravitational lenses, we propose one orbit
of ACS-WFC
F814W imaging for each of 50 high-probability strong galaxy-galaxy
lens
candidates. These observations will confirm new lens
systems and permit
immediate and accurate photometry, shape measurement, and
mass modeling
of the lens galaxies. The lenses delivered by the SLACS
Survey all show
extended source structure, furnishing more constraints on
the projected
lens potential than lensed-quasar image positions. In
addition, SLACS
lenses have lens galaxies that are much brighter than
their lensed
sources, facilitating detailed photometric and dynamical
observation of
the former. When confirmed lenses from this proposal are
combined with
lenses discovered by SLACS in Cycles 13 and 14, we expect
the final
SLACS lens sample to number 80--100: an approximate
doubling of the
number of known galaxy-scale strong gravitational lenses
and an
order-of-magnitude increase in the number of optical
Einstein rings. By
virtue of its homogeneous selection and sheer size, the
SLACS sample
will allow an unprecedented exploration of the mass
structure of the
early-type galaxy population as a function of all other
observable
quantities. This new sample will be a valuable resource to
the
astronomical community by enabling qualitatively new
strong lensing
science, and as such we will waive all but a short
{3-month} proprietary
period on the observations.
FGS 10612
Binary Stars in Cyg OB2: Relics of Massive Star Formation
in a
Super-Star Cluster
We propose to make a high angular resolution SNAP survey
of the massive
stars in the nearby, super-star cluster Cyg OB2. We will use
FGS1r TRANS
mode observations to search for astrometric companions in
the separation
range of 0.01 to 1.00 arcsec and in the magnitude
difference range
smaller than 4 magnitudes. The observations will test the
idea that the
formation of very massive stars involves mergers and the
presence of
nearby companions. Discovery of companions to massive
stars in this
relatively nearby complex will provide guidance in the
interpretation of
apparently supermassive stars in distant locations. The
search for
companions will also be important for verification of
fundamental
parameters derived from spectroscopy, adjustments to main
sequence
fitting and distance estimations, determining third light
contributions
of eclipsing binaries, identifying wide colliding wind
binaries,
studying the relationship between orbital and spin angular
momentum, and
discovering binaries amenable to future mass
determinations. The massive
star environment in Cyg OB2 may be similar to the kinds
found in the
earliest epoch of star formation, so that a study of the
role of
binaries in Cyg OB2 will help us understand the formation
processes of
the first stars in the Universe.
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 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.
NIC3 10792
Quasars at Redshift z=6 and Early Star Formation History
We propose to observe four high-redshift quasars {z=6} in
the NIR in
order to estimate relative Fe/Mg abundances and the
central black hole
mass. The results of this study will critically constrain
models of
joint quasar and galaxy formation, early star formation,
and the growth
of supermassive black holes. Different time scales and
yields for
alpha-elements {like O or Mg} and for iron result into an
iron
enrichment delay of ~0.3 to 0.6 Gyr. Hence, despite the
well-known
complexity of the FeII emission line spectrum, the ratio
iron/alpha -
element is a potentially useful cosmological clock. The central
black
hole mass will be estimated based on a recently revised
back hole mass -
luminosity relationship. The time delay of the iron
enrichment and the
time required to form a supermassive black hole {logM>8
Msol, tau
~0.5Gyr} as evidenced by quasar activity will be used to
date the
beginning of the first intense star formation, marking the
formation of
the first massive galaxies that host luminous quasars, and
to constrain
the epoch when supermassive black holes start to grow by
accretion.
NIC3 11080
Exploring the Scaling Laws of Star Formation
As a variety of surveys of the local and distant Universe
are
approaching a full census of galaxy populations, our
attention needs to
turn towards understanding and quantifying the physical
mechanisms that
trigger and regulate the large-scale star formation rates
{SFRs} in
galaxies.
NIC3 10504
Characterizing the Sources Responsible for Cosmic
Reionization
Our group has demonstrated the role that massive clusters,
acting as
powerful cosmic lenses, can play in constraining the
abundance and
properties of low-luminosity star- forming sources beyond
z~6; such
sources are thought to be responsible for ending cosmic
reionization.
The large magnification possible in the critical regions
of well-
constrained clusters brings sources into view that lie at
or beyond the
limits of conventional exposures such as the UDF, as well
as those in
imaging surveys being undertaken with IRAC onboard
Spitzer. We have
shown that the combination of HST and Spitzer is
particularly effective
in delivering the physical properties of these distant
sources,
constraining their mass, age and past star formation
history.
Indirectly, we therefore gain a valuable glimpse to yet
earlier epochs.
Recognizing the result {and limitations} of the UDF
exposure, we propose
a systematic search through 6 lensing clusters with ACS
and NICMOS for
further z~6-7 sources in conjunction with existing deep
IRAC data. Our
survey will mitigate cosmic variance and extend the search
both to lower
luminosities and, by virtue of the NICMOS/IRAC
combination, to higher
redshift. The goal is to count and characterize
representative sources
at z~6-10 and to delineate the redshift range of activity
for the
planning of future observations.
WFPC2 10807
The knotty jet of He 2-90: An ideal laboratory for
studying the
formation and propagation of jets in dying stars
Previous WFPC2 observations have led to the serendipitous
discovery of
an extended, highly-collimated, ``pulsed" bipolar jet
emanating from a
compact planetary nebula, He 2- 90. Subsequently, an
average proper
motion of the knots in the jet was measured, which
together with radial
velocities, enabled us to characterise the basic physical
properties of
the jet. The knotty jet in He 2-90 resembles other
prominent examples of
pulsed jets in young stellar objects or symbiotic stars,
but is probably
by far the best example yet of a non-relativistic,
symmetric, jet in a
``clean" astrophysical environment. The formation
{acceleration and
collimation} of jets is not fully understood, specially in
the case of
jets in dying stars. We now propose to re-image He 2-90
with WFPC2 and
exploit the factor 3.5 longer time baseline now available
from the
first-epoch observations in September 1999, in order to
measure the
proper motion of individual knots in the jet with
unprecedented
accuracy. These data will enable us to characterise the
ejection history
of the source, specially deviations from a constant period
{latter is
related to the binary period of the system}, e.g., due to
instabilities
in the accretion mechanism. We will also be able to test
if the ejection
mechanism is symmetric: any deviation in the ejection
history of the
knots in the opposing jet beams, will indicate a magnetic
field
structure and/or the accretion disk which is not symmetric
across the
equatorial plane. We will also carry out deep imaging with
the ACS/WFC
camera in order to determine the shapes/sizes of a large
number of
knots. The shapes/sizes of the knots, and changes with
distance from the
source probe the strength of the magnetic field inside the
jet. HRC
imaging of the central source and jet on sub-arcsecond
scales will be
carried out to probe the magnetic field close to the jet
source, and
deviations from linearity in the jet-beam which may result
from
instabilities in the magnetic field. These data will allow
us to
significantly improve our existing 2- dimensional MHD
model of the
He2-90 jet, and/or provide impetus for new 3-dimensional
models.
WFPC2 10900
Optical polarimetry of PSR B0540-69 and its synchrotron
nebula.
Polarization measurements of pulsars and of their
synchrotron nebulae
are uniquely able to provide deep insights into the highly
magnetized
relativistic environment of young rotating neutron stars.
Apart from the
radio band, pulsar polarization is best measured in the
optical, for the
rare cases of detectable optical emission. One of the
brightest pulsars
together with Crab {PSR B0531+21} and Vela {PSR B0833-45},
for which
optical polarization measurements support the newly
developed two-pole
caustic model {TPC}, is PSR B0540-69 in the Large
Magellanic Clouds,
often referred as the Crab Twin for their overall
similarities in both
age and energetics. Together with the Crab, PSR B0540-69
is also the
only pulsar embedded in a synchrotron nebula visible at
optical
wavelengths. We plan to observe PSR B0540-69 and its
compact nebula {4
arcsec diameter} with the Advanced Camera for Surveys
{ACS} and the Wide
Field Channel {WFC} detector using UV and visual
polarization filters.
Thanks to the superb angular resolution of ACS, these
observations will
allow us to spectacularly resolve the pulsar from its
nebular
background, providing the first firm measure of the pulsar
polarization
which will be crucial to assess, on a broader sample, the
validity of
the TPC model with respect to other pulsars magnetosphere
models. These
observations will also provide the first detailed
polarization map of
the nebula, including the jet and the torus seen in our
previous WFPC2
images.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST:
18105-1 - MSS/CSS Gyro2 Converged & Remove Gyro2
Test#37.
18054-0 - Preview KF Sun Vector Data via Telemetry Diags.
18108-1 - PCS KF OOT Support.
18109-1 - PCS KF OOT Support.
18106-0 - MSS/CSS Converged Add/Remove Gyro1Tests#19.
18054-0 - Preview KF Sun Vector Data via Telemetry Diags.
SCHEDULED
SUCCESSFUL
FGS
GSacq
09
09
FGS
REacq
04
04
OBAD with Maneuver
26
26
COMPLETED OPS NOTES: (None)
SIGNIFICANT EVENTS:
Evaluation of Universal Kalman Filter performance
continued. Multiple
text segments were executed, all of them successfully.
Details follow
The filter was configured to disable the CSS input
at 172/14:09, leaving only the MSS input enabled. The Gyro
2 sensor
input was added to the converged KF filter at 172/14:20.
The gyro input
was added during a vehicle slew and during a fast changing
B-field. All
UKF parameters showed nominal operation. The test was to
monitor the
addition of the Gyro2 sensor input into an MSS only
converged filter
(M_G2_RVF, Test #37). The Gyro2 input was removed at
172/14:41, leaving
only the MSS sensor input enabled.
The Gyro1 sensor input was added to the converged KF
filter at
172/19:48. The filter was configured to use only the MSS
input. The gyro
input was added during a vehicle slew and a fast changing
B-field. All
UKF parameters showed nominal operation. The test was to
monitor the
addition of the Gyro1 sensor input into an MSS only
converged filter
(M_G1_RVF, Test #19). The Gyro1 input was later removed at
172/21:32
during a vehicle slew and a fast changing B-field. The
removal of the
Gyro1 input completed the second part of the Ops Request
(M_G1_HVF, Test
#23). Again, all UKF parameters showed nominal operation.
The removal of
the Gyro1 input leaves the KF configured to use MSS sensor
input only.
The test above completes the KF Convergence testing. Two
long-term tests
remain to configure the KF for MSS/Gyro2 and MSS/CSS/Gyro2
for one week
each.