HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4260
PERIOD COVERED: UT December 14, 2006 (DOY 348)
OBSERVATIONS SCHEDULED
ACS/HRC/WFPC2/NIC3 10842
A Cepheid Distance to the Coma Cluster
We propose to use the Advanced Camera for Surveys to search for
Cepheid
variables in two spiral galaxies in the core of the Coma cluster. A
direct application of the canonical primary distance indicator at
100
Mpc will measure the far-field Hubble constant free of many of the
systematic uncertainties which beset current determinations relying
on
secondary indicators. Establishing the far-field H_o with Cepheids
will
provide one of the strongest links in the extragalactic distance
scale
and will directly calibrate the fiducial fundamental plane of
elliptical
galaxies in Coma. With ACS/HRC, S/N=5 to 10 or better can be reached
for
Cepheids with periods of 40d to 70d at mean light in 5 orbits with
the
F606W filter if H_o=72 km/s/Mpc. Efficient detection and phasing can
be
done with twelve epochs optimally spaced for periods of 40-70d.
ACS/WFC 10795
The Largest Galaxies in the Local Universe: New Light on Disk Galaxy
Formation?
In the standard scenario of disk galaxy formation in a hierarchical
Universe, large disks form late via the accretion of either hot or
cold
gas. Direct observational evidence for such late accretion- driven
disk
formation has not been forthcoming. In this proposal, we describe
the
discovery of a rare new type of galaxy that may be examples of
massive
disks in the process of assembly. We have identified a sample of
three
such galaxies selected from the SDSS DR4. They are extremely large
{diameters over 100 kpc} and highly luminous systems with amorphous
structures {no obvious spiral arms or bulges}. They are larger than
the
largest normal spirals in the survey, and have significantly bluer
colors, lower metallicities, lower dust extinctions, higher UV
luminosities and higher total star formation rates than the most
massive
ordinary spirals. We request HST images in the rest-frame near-UV
and
red to provide detailed maps of the underlying structure of these
galaxies as well as the distribution of the young stars. The
interstellar medium of these galaxies is evidently quite different
from
that of normal large spirals and starburst galaxies and they may be
experiencing a different mode of star formation. We believe they are
worthy of further investigation with the high-resolution imaging
capabilities of HST.
ACS/WFC 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.
ACS/WFC 10905
The Dynamic State of the Dwarf Galaxy Rich Canes Venatici I
Region
With accurate distances, the nearest groups of galaxies can be
resolved
in 3 dimensions and the radial component of the motions of galaxies
due
to local density perturbations can be distinquished from
cosmological
expansion components. Currently, with the ACS, galaxy distances within
8
Mpc can be measured effectively and efficiently by detecting the tip
of
the red giant branch {TRGB}. Of four principal groups at high
galactic
latitude in this domain, the Canes Venatici I Group {a} is the least
studied, {b} is the most populated, though overwhelmingly by dwarf
galaxies, and {c} is likely the least dynamically evolved. It is
speculated that galaxies in low mass groups may fail to retain
baryons
as effectively as those in high mass groups, resulting in
significantly
higher mass-to-light ratios. The CVn I Group is suspected to lie in
the
mass regime where the speculated astrophysical processes that affect
baryon retention are becoming important.
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, ACS/WFC 10802
SHOES-Supernovae, HO, for the Equation of State of Dark energy
The present uncertainty in the value of the Hubble constant
{resulting
in an uncertainty in Omega_M} and the paucity of Type Ia supernovae
at
redshifts exceeding 1 are now the leading obstacles to determining
the
nature of dark energy. We propose a single, integrated set of
observations for Cycle 15 that will provide a 40% improvement in
constraints on dark energy. This program will observe known Cepheids
in
six reliable hosts of Type Ia supernovae with NICMOS, reducing the
uncertainty in H_0 by a factor of two because of the smaller
dispersion
along the instability strip, the diminished extinction, and the
weaker
metallicity dependence in the infrared. In parallel with ACS, at the
same time the NICMOS observations are underway, we will discover and
follow a sample of Type Ia supernovae at z > 1. Together, these
measurements, along with prior constraints from WMAP, will provide a
great improvement in HST's ability to distinguish between a static,
cosmological constant and dynamical dark energy. The Hubble Space
Telescope is the only instrument in the world that can make these IR
measurements of Cepheids beyond the Local Group, and it is the only
telescope in the world that can be used to find and follow supernovae
at
z > 1. Our program exploits both of these unique capabilities of HST
to
learn more about one of the greatest mysteries in science.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports
of potential non-nominal performance that will be investigated.)
HSTARS:
10558 - REACQ(2,1,2) fails during LOS
Upon acquisition of signal at 10:38:40, QF2STOPF and QSTOP flags
were
set
and vehicle was in gyro control. REACQ(2,1,2) at 09:44:49
failed, primary GSACQ(2,1,2) at 08:13:58 was successful. Further
information after engineering recorder dump.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSacq
07
07
FGS
REacq
08
07
OBAD with Maneuver
30
30
SIGNIFICANT EVENTS: (None)
-Lynn
Lynn F. Bassford
CHAMP HST Missions Operations Manager
Lockheed Martin Mission Services (LMMS)
GSFC PH#: 301-286-2876
"The Hubble Space Telescope is the astronomical observatory and
key to unlocking the most cosmic mysteries of the past, present and
future." - 7/26/6