HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4179
PERIOD COVERED: UT August 16, 2006 (DOY 228)
OBSERVATIONS SCHEDULED
ACS/HRC 10870
The Ring Plane Crossings of Uranus in 2007
The rings of Uranus turn edge-on to Earth in May and August 2007. In
between, we will have a rare opportunity to see the unlit face of
the
rings. With the nine optically thick rings essentially invisible, we
will
observe features and phenomena that are normally lost in their glare.
We
will use this opportunity to search thoroughly for the embedded
"shepherd" moons long believed to confine the edges of the
rings,
setting a mass limit roughly 10 times smaller than that of the
smallest
shepherd currently known, Cordelia. We will measure the vertical
thicknesses of the rings and study the faint dust belts only known
to
exist from a single Voyager image. We will also study the colors of
the
newly-discovered faint, outer rings; recent evidence suggests that
one
ring is red and the other blue, implying that each ring is dominated
by
a different set of physical processes. We will employ near-edge-on
photometry from 2006 and 2007 to derive the particle filling factor
within the rings, to observe how ring epsilon responds to the
"traffic
jam" as particles pass through its narrowest point, and to test
the
latest models for preserving eccentricities and apse alignment
within
the rings. Moreover, this data set will allow us to continue
monitoring
the motions of the inner moons, which have been found to show
possibly
chaotic orbital variations; by nearly doubling the time span of the
existing ACS astrometry, the details of the variations will become
much
clearer.
ACS/HRC/WFC 10758
ACS CCDs daily monitor
This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in
ACS CCD detectors. The files, biases and dark will be used to create
reference files for science calibration. This programme will be for
the
entire lifetime of ACS. Changes from cycle 13:- The default gain for
WFC
is 2 e-/DN. As before bias frames will be collected for both gain 1
and
gain 2. Dark frames are acquired using the default gain {2}. This
program cover the period May, 31 2006- Oct, 1-2006. The first half
of
the program has a different proposal number: 10729.
ACS/HRC/WFC 10896
An Efficient ACS Coronagraphic Survey for Debris Disks around Nearby
Stars
We propose to finish our Cycle 11 optical survey for nearby debris
disks
using the ACS/HRC coronagraph. Out of 43 orbits originally proposed
for
the survey, 23 orbits were allocated, leading to a survey of 22
stars,
from which two new debris disks were imaged for the first time. Our
analysis of the initial survey gives an empirical estimate for the
detection rate of debris disks relative to heliocentric distance and
dust optical depth. Our target list for Cycle 15 is now optimized to
yield more frequent disk detections. Likewise our observing strategy
is
improved to maximize sensitivity per telescope orbit allocated.
Therefore we present the most efficient survey possible. The
scientific
motivation is to obtain scattered light images of previously
unresolved
debris disks to determine their viewing geometry and physical
architecture, both of which may characterize the underlying
planetary
system. We choose 25 debris disk targets for which we predict a
detection rate of 25% ? 5%. Four targets have extrasolar planets
from
which the viewing geometry revealed by a disk detection will resolve
the
v sin{i} ambiguity in the planet masses. These targets present the
remarkable opportunity of finally seeing a debris disk in system
with
known planets.
ACS/WFC 10592
An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in
the
Local Universe
At luminosities above 10^11.4 L_sun, the space density of
far-infrared
selected galaxies exceeds that of optically selected galaxies. These
`luminous infrared galaxies' {LIRGs} are primarily interacting or
merging disk galaxies undergoing enhanced star formation and Active
Galactic Nuclei {AGN} activity, possibly triggered as the objects
transform into massive S0 and elliptical merger remnants. We propose
ACS/WFC imaging of a complete sample of 88 L_IR > 10^11.4 L_sun
luminous
infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS:
i.e.,
60 micron flux density > 5.24 Jy}. This sample is ideal not only in
its
completeness and sample size, but also in the proximity and
brightness
of the galaxies. The superb sensitivity, resolution, and field of
view
of ACS/WFC on HST enables a unique opportunity to study the detailed
structure of galaxies that sample all stages of the merger process.
Imaging will be done with the F439W and F814W filters {B and I-band}
to
examine as a function of both luminosity and merger state {i} the
evidence at optical wavelengths of star formation and AGN activity
and
the manner in which instabilities {bars and bridges} in the galaxies
may
funnel material to these active regions, {ii} the relationship
between
star formation and AGN activity, and {iii} the structural properties
{AGN, bulge, and disk components} and fundamental parameters
{effective
radius and surface brightness} of LIRGs and their similarity with
putative evolutionary byproducts {elliptical, S0 and classical AGN
host
galaxies}. This HST survey will also bridge the wavelength gap between
a
Spitzer imaging survey {covering seven bands in the 3.6-160 micron
range} and a GALEX UV imaging survey of these galaxies, but will
resolve
complexes of star clusters and multiple nuclei at resolutions well
beyond the capabilities of either Spitzer or GALEX. The combined
datasets will result in the most comprehensive multiwavelength study
of
interacting and merging galaxies to date.
ACS/WFC 10816
The Formation History of Andromeda's Extended Metal-Poor Halo
We propose deep ACS imaging in the outer spheroid of the Andromeda
galaxy, in order to measure the star formation history of its true
halo.
For the past 20 years, nearly all studies of the Andromeda
"halo" were
focused on the spheroid within 30 kpc of the galaxy's center, a
region
now known to host significant substructure and populations with high
metallicity and intermediate ages. However, two groups have recently
discovered an extended metal-poor halo beyond 30 kpc; this population
is
distinct in its surface-brightness profile, abundance distribution,
and
kinematics. In earlier cycles, we obtained deep images of the inner
spheroid {11 kpc on the minor axis}, outer disk {25 kpc on the major
axis}, and giant tidal stream, yielding the complete star formation
history in each field. We now propose deep ACS imaging of 4 fields
bracketing this 30 kpc transition point in the spheroid, so that the
inner spheroid and the extended halo populations can be
disentangled,
enabling a reconstruction of the star formation history in the halo.
A
wide age distribution in the halo, as found in the inner spheroid,
would
imply the halo was assembled through ongoing accretion of satellite
galaxies, while a uniformly old population would be a strong
indication
that the halo was formed during the early rapid collapse of the
Andromeda proto-galaxy.
WFPC2 10631
Intermediate-Age Globular Clusters in M31
We propose deep ACS/WFC imaging of four halo M31 globular clusters
in
order to derive their horizontal branch morphologies. Our
spectroscopic
investigation of their integrated light identifies them as members of
an
intermediate-age population of globular clusters in M31. Since our
spectroscopic results are based on the analysis of Balmer absorption
lines, we need to secure our results against an artificial
juvenation
due to extreme horizontal branch morphologies. The proposed
observations
will allow a clear-cut answer to the question of whether
spectroscopically derived intermediate-age estimates are due to
genuinely younger ages or are the result of anomalously hot
horizontal
branch morphologies. Either way, our results will have important
implications for spectroscopically derived ages and metallicities of
distant stellar populations. Because of the high spatial resolution
of
the proposed ACS/WFC observations we will also derive accurate
surface
brightness profiles of our target globular clusters and investigate
the
influence of stellar density on horizontal branch morphology.
Moreover,
together with deep parallel WFPC2 fields we will study the
metallicity
dispersion of the background stellar population in M31 as a function
of
galactocentric radius.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports
of potential non-nominal performance that will be investigated.)
HSTARS:
10404 - GSacq(2,1,2) failed. @ 228/10:15:57z
GSacq(2,1,2) failed to RGA control (FGS Coarse Track failed - Timed
out
waiting for data valid ) was received.
10405 - ACS 954 GS Acquisition failure.
At 228/10:23:12 ACS 954 (TDF was down when small angle maneuver was
commanded during a target acquisition) was received due to GSacq
failure.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSacq
08
07
FGS
REacq
07
07
OBAD with Maneuver
30
30
SIGNIFICANT EVENTS: (None)
-Lynn
Lynn F. Bassford
CHAMP HST Missions Operations Manager
Lockheed Martin Technical Operations
GSFC PH#: 301-286-2876
Cell/Voice Mail: 240-603-4873 Text/Pager:
2406034873@messaging.sprintpcs.com
"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
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