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Daily Report #4152



 
 
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Old July 11th 06, 03:26 PM posted to sci.astro.hubble
Lynn Bassford
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Default Daily Report #4152

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4152

PERIOD COVERED: UT July 10, 2006 (DOY 191)

OBSERVATIONS SCHEDULED

ACS/HRC 10512

Search for Binaries Among Faint Jupiter Trojan Asteroids

We propose an ambitious SNAPSHOT program to survey faint Jupiter
Trojan asteroids for binary companions. We target 150 objects, with
the expectation of acquiring data on about 50%. These objects span
Vmag = 17.5-19.5, a range inaccessible with ground-based adaptive
optics. We now have a significant sample from our survey of brighter
Trojans to suggest that the binary fraction is similar to that which
we find among brighter main-belt asteroids, roughly 2%. However, our
observations suggest a higher binary fraction for smaller main-belt
asteroids, probably the result of a different formation mechanism
{evident also from the physical characteristics of the binaries}.
Because the collision environment among the Trojans is similar to that
of the Main Belt, while the composition is likely to be very
different, sampling the binary fraction among the fainter Trojans
should help us understand the collisional and binary formation
mechanisms at work in various populations, including the Kuiper Belt,
and help us evaluate theories for the origin of the Trojans.
Calibration of and constraints on models of binary production and
collisional evolution can only be done using these large-scale,
real-life physical systems that we are beginning now to find and
utilize.

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/WFC 10503

The Star Formation Histories of Early Type Dwarf Galaxies in Low
Density Environments: Clues from the Sculptor Group

We seek HST ACS/WFC time to conduct a detailed study of the stellar
populations of 5 early-type {dE, dE/dIrr} dwarf galaxies in the nearby
{~1.5 to 4 Mpc} Sculptor group. Four of these systems have been
recently found to contain modest amounts of HI, and existing
ground-based and HST snapshot data point to the potential presence of
small populations of young {blue} stars in at least three of these
systems. Consequently, they resemble the Local Group 'transition'
objects Phoenix and LGS3. The relative number of such transition
systems is thus substantially larger in the low density environment of
the Scl group than for the Local Group. Detailed stellar populations
studies will allow estimation of the star formation histories, via
stellar population modelling of the color- magnitude diagrams, of the
target dwarfs, which in turn will connect to gas consumption and
retention rates. For the two nearer dwarfs we aim to reach below the
horizontal branch {a first for any system beyond the Local Group}
equivalent to a main sequence turnoff age of ~1 Gyr. The observations
of these two systems will also allow detection of RR Lyrae variables
and thus direct confirmation of the presence of old populations. For
the other three dwarfs will we cover the first 2.5 mags of the red
giant branch, equivalent to the main sequence termination for a ~300
Myr population. The results will have implications for theories of
galaxy formation and evolution, particularly with regard to the
evolutionary relation between low luminosity dEs and dwarf irregulars.

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 10624

Solving the Mystery of the Short-Hard Gamma-Ray Bursts

Eight years after the afterglow detections that revolutionized studies
of the long-soft gamma-ray bursts, not even one afterglow of a
short-hard GRB has been seen, and the nature of these events has
become one of the most important problems in GRB research. The Swift
satellite, expected to be in full operation throughout Cycle 14, will
report few-arcsecond localizations for short-hard bursts in minutes,
enabling prompt, deep optical afterglow searches for the first time.
Discovery and observation of the first short-hard optical afterglows
will answer most of the critical questions about these events: What
are their distances and energies? Do they occur in distant galaxies,
and if so, in which regions of those galaxies? Are they the result of
collimated or quasi-spherical explosions? In combination with an
extensive rapid-response ground-based campaign, we propose to make the
critical high-sensitivity HST TOO observations that will allow us to
answer these questions. If theorists are correct in attributing the
short-hard bursts to binary neutron star coalescence events, then they
will serve as signposts to the primary targeted source population for
ground-based gravitational-wave detectors, and short-hard burst
studies will have a vital role to play in guiding those observations.

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.

NIC3/ACS/WFC 10504

Characterizing the Sources Responsible for Cosmic Reionization

Our group has demonstrated the role that massive clusters, acting as
powerful cosmic lenses, can play in constraining the abundance and
properties of low-luminosity star-forming sources beyond z~6; such
sources are thought to be responsible for ending cosmic reionization.
The large magnification possible in the critical regions of
well-constrained clusters brings sources into view that lie at or
beyond the limits of conventional exposures such as the UDF, as well
as those in imaging surveys being undertaken with IRAC onboard
Spitzer. We have shown that the combination of HST and Spitzer is
particularly effective in delivering the physical properties of these
distant sources, constraining their mass, age and past star formation
history. Indirectly, we therefore gain a valuable glimpse to yet
earlier epochs. Recognizing the result {and limitations} of the UDF
exposure, we propose a systematic search through 6 lensing clusters
with ACS and NICMOS for further z~6-7 sources in conjunction with
existing deep IRAC data. Our survey will mitigate cosmic variance and
extend the search both to lower luminosities and, by virtue of the
NICMOS/IRAC combination, to higher redshift. The goal is to count and
characterize representative sources at z~6-10 and to delineate the
redshift range of activity for the planning of future observations.

WFPC2 10534

Active Atmospheres on Uranus and Neptune

We propose Snapshot observations of Uranus and Neptune to monitor
changes in their atmospheres on time scales of weeks, months, and
years. Uranus is rapidly approaching equinox in 2007, with another 4
degrees of latitude becoming visible every year. Recent HST
observations during this epoch {including 6818: Hammel, Lockwood, and
Rages; 8680: Hammel, Rages, Lockwood, and Marley; 8634: Rages, Hammel,
Lockwood, Marley, and McKay; and 10170: Rages, Hammel, Lockwood, and
Marley} have revealed strongly wavelength-dependent latitudinal
structure and the presence of numerous visible-wavelength cloud
features in the northern hemisphere. Long- term ground-based
observations {Lockwood and Thompson 1999} show seasonal brightness
changes whose origins are not well understood. Recent near-IR images
of Neptune obtained using adaptive optics on the Keck Telesccope
together with images from our Cycle 9 Snapshot program {8634} show a
general increase in activity at south temperate latitudes as well as
the possible development of another Great Dark Spot. Further Snapshot
observations of these two dynamic planets will elucidate the nature of
long-term changes in their zonal atmospheric bands and clarify the
processes of formation, evolution, and dissipation of discrete albedo
features.

WFPC2 10748

WFPC2 CYCLE 14 Standard Darks

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

#10351 - GSAcq(2,3,2) Failed to RGA Control @ 191/1553z

The GSAcq(2,3,2) scheduled at 191/15:53:34 - 16:01:39 failed to RGA
Hold due to stop flag (QF2STOPF) indication on FGS-2. Pre-acquisition
OBADs had (RSS) attitude error corrections values of 5160.83 and 10.42
arcseconds. Post-acquisition OBAD/MAP not scheduled. Possible
Observations affected: ACS 38.

#10352 - REACQ(2,3,2) fails to RGA control @ 191/1847z

At acquisition of signal at 191/19:06:09, vehicle was in gyro control
with QF2STOPF and QSTOP flags set. REACQ(2,3,2) at 191/18:47:18 failed
to acquire lock. No Scan Step Limit or Search Radius Limit flags were
seen. GSACQ(2,3,2) at 15:54:19 and REACQ(2,3,2) at 17:11:15 were
successful. REACQ(2,3,2) at 20:23:12 was also successful. Observations
affected: ACS 43 to 46. GSAcq(2,3,2) @ 15:54:19 failed to RGA Hold,
reference HSTAR #10351.

#10355 GSAcq (2,3,2) failed due to search radius limit exceeded
@192/08:51:53z

GSAcq (2,3,2) scheduled at 192/08:46:56-08:54:28 failed to RGA control
due to search radius limit exceeded on FGS 2. Possible observations
effected: ACS 62 At 192/08:41:14) received two 486 ESB 1805's (FHST
Moving target detected). Pre-acquisition OBADs had (RSS) attitude
error corrections values of 1578.03 and 12.04 arc-seconds.
Post-acquisition OBAD/MAP not scheduled. At 192/08:59:26 received 486
ESB a07 (CT TIMEOUT IN DET DV).

COMPLETED OPS REQUEST:
#17819-1 Install SMAC20 Versions K & L @ 191/1925z
#17813-1 Enable ESBs 1201 and 1202 for Battery 3 BCT @ 192/0749z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 10 8 191/1553z (HSTAR 10351)
192/0851z (HSTAR 10355)
FGS REacq 5 4 191/1847z (HSTAR 10352)
OBAD with Maneuver 26 26

SIGNIFICANT EVENTS: (None)


 




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