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Daily Report # 4326



 
 
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Old March 26th 07, 02:37 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report # 4326

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)


 




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