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 # 4326
PERIOD COVERED: UT March 23,24,25, 2007 (DOY 082,083,084)
OBSERVATIONS SCHEDULED
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration - CR Persistence Part 6
A new proceedure proposed to alleviate the CR-persistence
problem of
NICMOS. Dark frames will be obtained immediately upon
exiting the SAA
contour 23, and everytime 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.
WFPC2 11096
Hubble Heritage imaging of Jupiter during the New Horizons
encounter HST
Proposal 11096
WFPC2 images of Jupiter in Feb 2007 in support of New
Horizons flyby of
Jupiter. This Hubble Heritage DD program is working in
concert with the
existing GO programs by John Clarke {10862} and John
Spencer {10871}.
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.
FGS 10989
Astrometric Masses of Extrasolar Planets and Brown Dwarfs
We propose observations with HST/FGS to estimate the
astrometric
elements {perturbation orbit semi-major axis and
inclination} of
extra-solar planets orbiting six stars. These companions
were originally
detected by radial velocity techniques. We have
demonstrated that FGS
astrometry of even a short segment of reflex motion, when
combined with
extensive radial velocity information, can yield useful
inclination
information {McArthur et al. 2004}, allowing us to
determine companion
masses. Extrasolar planet masses assist in two ongoing
research
frontiers. First, they provide useful boundary conditions
for models of
planetary formation and evolution of planetary systems.
Second, knowing
that a star in fact has a plantary mass companion,
increases the value
of that system to future extrasolar planet observation
missions such as
SIM PlanetQuest, TPF, and GAIA.
FGS 10912
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 10910
HST / Chandra Monitoring of a Dramatic Flare in the M87
Jet
As the nearest galaxy with an optical jet, M87 affords an
unparalleled
opportunity to study extragalactic jet phenomena at the
highest
resolution. During 2002, HST and Chandra monitoring of the
M87 jet
detected a dramatic flare in knot HST-1 located ~1"
from the nucleus.
Its optical brightness eventually increased seventy-fold
and peaked in
2005; the X- rays show a similarly dramatic outburst. In
both bands
HST-1 is still extremely bright and greatly outshines the
galaxy
nucleus. To our knowledge this is the first incidence of
an optical or
X-ray outburst from a jet region which is spatially
distinct from the
core source -- this presents an unprecedented opportunity
to study the
processes responsible for non- thermal variability and the
X-ray
emission. We propose five epochs of HST/ACS flux
monitoring during Cycle
15, as well as seven epochs of Chandra/ACIS observation
{5ksec each,
five Chandra epochs contemporary with HST}. At two of the
HST/ACS epochs
we also gather spectral information and map the magnetic
field
structure. The results of this investigation are of key
importance not
only for understanding the nature of the X-ray emission of
the M87 jet,
but also for understanding flares in blazar jets, which
are highly
variable, but where we have never before been able to
resolve the
flaring region in the optical or X-rays. These
observations will allow
us to test synchrotron emission models for the X- ray
outburst,
constrain particle acceleration and loss timescales, and
study the jet
dynamics associated with this flaring component.
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.
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.
NIC2 10849
Imaging Scattered Light from Debris Disks Discovered by
the Spitzer
Space Telescope around 21 Sun-like Stars
We propose to use the high-contrast capability of the
NICMOS coronagraph
to image a sample of newly discovered circumstellar disks
associated
with Sun-like stars. These systems were identified by
their strong
thermal infrared {IR} emission with the Spitzer Space
Telescope as part
of the Spitzer Legacy Science program titled "The
Formation and
Evolution of Planetary Systems" {FEPS, P.I.:
M.Meyer}. Modeling of the
thermal excess emission from the spectral energy
distributions alone
cannot distinguish between narrowly confined high-opacity
disks and
broadly distributed, low-opacity disks. By resolving light
scattered by
the circumstellar material, our proposed NICMOS
observations can break
this degeneracy, thus revealing the conditions under which
planet
formation processes are occuring or have occured. For
three of our
IR-excess stars that have known radial-velocity planets,
resolved
imaging of the circumstellar debris disks may further
offer an
unprecedented view of planet-disk interactions in an
extrasolar
planetary system. Even non-detections of the light
scattered by the
circumstellar material will place strong constraints on
the disk
geometries, ruling out disk models with high optical
depth. Unlike
previous disk imaging programs, our program contains a
well-defined
sample of ~1 solar mass stars covering a range of ages
from 3 Myr to 3
Gyr, thus allowing us to study the evolution of disks from
primordial to
debris for the first time. The results from our program
will greatly
improve our understanding of the architecture of debris
disks around
Sun-like stars, and will create a morphological context
for the
existence of our own solar system. This proposal is for a
continuation
of an approved Cycle 14 program {GO/10527, P.I.: D.
Hines}.
ACS/SBC 10815
The Blue Hook Populations of Massive Globular Clusters
Blue hook stars are a class of hot {~35,000 K} subluminous
horizontal
branch stars that have been recently discovered using HST
ultraviolet
images of the globular clusters omega Cen and NGC 2808.
These stars
occupy a region of the HR diagram that is unexplained by
canonical
stellar evolution theory. Using new theoretical
evolutionary and
atmospheric models, we have shown that the blue hook stars
are very
likely the progeny of stars that undergo extensive
internal mixing
during a late helium core flash on the white dwarf cooling
curve. This
"flash mixing" produces an enormous enhancement
of the surface helium
and carbon abundances, which suppresses the flux in the
far ultraviolet.
Although flash mixing is more likely to occur in stars
that are born
with high helium abundances, a high helium abundance, by
itself, does
not explain the presence of a blue hook population - flash
mixing of the
envelope is required. We propose ACS ultraviolet
{SBC/F150LP and
HRC/F250W} observations of the five additional globular
clusters for
which the presence of blue hook stars is suspected from
longer
wavelength observations. Like omega Cen and NGC 2808,
these five targets
are also among the most massive globular clusters, because
less massive
clusters show no evidence for blue hook stars. Because our
targets span
1.5 dex in metallicity, we will be able to test our
prediction that
flash-mixing should be less drastic in metal-rich blue
hook stars. In
addition, our observations will test the hypothesis that
blue hook stars
only form in globular clusters massive enough to retain
the helium-
enriched ejecta from the first stellar generation. If this
hypothesis is
correct, then our observations will yield important
constraints on the
chemical evolution and early formation history in globular
clusters, as
well as the role of helium self-enrichment in producing
blue horizontal
branch morphologies and multiple main sequence turnoffs.
Finally, our
observations will provide new insight into the formation
of the hottest
horizontal branch stars, with implications for the origin
of the hot
helium-rich subdwarfs in the Galactic field.
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 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: (None)
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq 32
32
FGS REacq
09
09
OBAD with Maneuver
82
82
SIGNIFICANT EVENTS: (None)