Daily Report #4165
- From: Lynn Bassford <lbassford@xxxxxxxxxxxx>
- Date: Fri, 28 Jul 2006 16:11:11 +0000 (UTC)
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 4165
PERIOD COVERED: UT July 27, 2006 (DOY 208)
OBSERVATIONS SCHEDULED
ACS/HRC 10860
The largest Kuiper belt object
The past year has seen an explosion in the discoveries of Pluto-sized
objects in the Kuiper belt. With the discoveries of the
methane-covered 2003 UB313 and 2005 FY9, the multiple satellite system
of 2003 EL61, and the Pluto-Charon analog system of Orcus and its
satellite, it is finally apparent that Pluto is not a unique oddball
at the edge of the solar system, but rather one of a family of
similarly large objects in the Kuiper belt and beyond. HST
observations over the past decade have been critical for understanding
the interior, surface, and atmosphere of Pluto and Charon. We propose
here a comprehensive series of observations designed to similarly
expand our knowledge of these recently discovered Pluto-sized and
near-Pluto-sized Kuiper belt objects. These observations will measure
objects' sizes and densities, explore the outcome of collisions in the
outer solar system, and allow the first ever look at the interior
structure of a Kuiper belt object. Our wide field survey that
discovered all of these objects is nearly finished, so after five
years of continuous searching we are finally almost complete in our
tally of these near-Pluto-sized objects. This large HST request is the
culmination of this half-decade search for new planetary-sized
objects. As has been demonstrated repeatedly by the approximately 100
previous orbits devoted to the study of Pluto, only HST has the
resolution and sensitivity for detailed study of these distant
objects. With these new Pluto-sized objects only now being discovered
we have a limited window left to still use HST for these critical
observations.
ACS/WFC 10775
An ACS Survey of Galactic Globular Clusters
We propose to conduct an ACS/WFC imaging survey of Galactic globular
clusters. We will construct the most extensive and deepest set of
photometry and astrometry to-date for these systems reaching a main
sequence mass of ~0.2 solar mass with S/N >= 10. We will combine these
data with archival WFPC2 and STIS images to determine proper motions
for the stars in our fields. The resultant cleaned cluster CMDs will
allow us to study a variety of scientific questions. These include
[but are not limited to] 1} the determination of cluster ages and
distances 2} the construction of main sequence mass functions and the
issue of mass segregation 3} the internal motions and dynamical
evolution of globular clusters, and 4} absolute cluster motions,
orbits, and the Milky Way gravitational potential. We anticipate that
the unique resource provided by the proposed treasury archive will
play a central role in the field of globular cluster studies for
decades, with a stature comparable to that of the Hubble Deep Field
for high redshift studies.
ACS/WFC/NIC2 10496
Decelerating and Dustfree: Efficient Dark Energy Studies with
Supernovae and Clusters
We propose a novel HST approach to obtain a dramatically more useful
"dust free" Type Ia supernovae {SNe Ia} dataset than available with
the previous GOODS searches. Moreover, this approach provides a
strikingly more efficient search-and-follow-up that is primarily
pre-scheduled. The resulting dark energy measurements do not share the
major systematic uncertainty at these redshifts, that of the
extinction correction with a prior. By targeting massive galaxy
clusters at z > 1 we obtain a five-times higher efficiency in
detection of Type Ia supernovae in ellipticals, providing a
well-understood host galaxy environment. These same deep cluster
images then also yield fundamental calibrations required for future
weak lensing and Sunyaev-Zel'dovich measurements of dark energy, as
well as an entire program of cluster studies. The data will make
possible a factor of two improvement on supernova constraints on dark
energy time variation, and much larger improvement in systematic
uncertainty. They will provide both a cluster dataset and a SN Ia
dataset that will be a longstanding scientific resource.
NIC1 10879
A search for planetary-mass companions to the nearest L dwarfs -
completing the survey
We propose to extend the most sensitive survey yet undertaken for very
low-mass companions to ultracool dwarfs. We will use NICMOS to
complete imaging of an all-sky sample of 87 L dwarfs in 80 systems
within 20 parsecs of the Sun. The combination of infrared imaging and
proximity allows us to search for companions with mass ratios q>0.25
at separations exceeding ~3 AU, while probing companions with q>0.5 at
~1.5 AU separation. This resolution is crucial, since no ultracool
binaries are known in the field with separations exceeding 15 AU.
Fifty L dwarfs from the 20-parsec sample have high- resolution
imaging, primarily through our Cycle 13 HST proposal which identified
six new binaries, including an L/T system. Here, we propose to target
the remaining 30 dwarfs
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.
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.
NIC2 10527
Imaging Scattered Light from Debris Disks Discovered by the Spitzer
Space Telescope Around 20 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 emission with the Spitzer Space Telescope as
part of the Spitzer Legacy Science program titled, "The Formation and
Evolution of Planetary Systems {FEPS}." Modelling of the thermal
excess emission in the form of spectral energy distributions alone
cannot distinguish between narrowly confined high opacity disks and
broadly distributed, low opacity disks. However, our proposed NICMOS
observations can, by imaging the light scattered from this material.
Even non- detections will place severe constraints on the disk
geometry, ruling out models with high optical depth. Unlike previous
disk imaging programs, our program contains a well defined sample of
solar mass stars covering a range of ages from ~10Myrs to a few Gyrs,
allowing us to study the evolution of disks from primordial to debris
for the first time. These results will greatly improve our
understanding of debris disks around Sun-like stars at stellar ages
nearly 10x older than any previous investigation. Thus we will have
fit a crucial piece into the puzzle concerning the formation and
evolution of our own solar system.
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:
#17864-0 Execute ROP NS-11 (Reset NICMOS Error Counter) @208/1337z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 06 06
FGS REacq 10 10
OBAD with Maneuver 30 30
SIGNIFICANT EVENTS: (None)
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