Daily Report #4153

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4153

PERIOD COVERED: UT July 11, 2006 (DOY 192)

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 10627

A Snapshot Survey of Post-AGB Objects and Proto-Planetary Nebulae

We propose an ACS/HRC snapshot survey of 50 post-AGB sources, objects
which have evolved from the AGB but may or may not become planetary
nebulae {PNe}. This survey will complement existing HST images of
proto-planetary nebulae {PPNe} and PNe in addressing circumstellar
envelope morphology as a function of: 1} the progenitor star mass; 2}
the chemical composition; and 3} evolutionary stage. We will connect
the observed diversity of nebualar shapes with the main physical and
chemical conditions characterizing post-AGB objects, to identify the
mechanism that breaks the symmetry of AGB mass loss. To our knowledge,
no previous HST projects have been specifically designed to address
this issue. From our database of 360 post-AGB candidates, we have
selected approximately 50 targets, none of which have been or are
being observed with HST, to sample different central star masses,
chemical compositions, and evolutionary stages, uniformly across the
sky. These new data will also provide important constraints to a
quantitative analysis of Spitzer Space Telescope {SST} observations
planned for a similar sample of objects. We will model the HST images
and SST spectra using our axisymmetric dust code 2-Dust, to derive
dust density distributions, pole to equator density ratios, dust shell
masses, inclination angles as well as dust composition.

ACS/HRC 10598

ACS Imaging of Fomalhaut: A Rosetta Stone for Debris Disks Sculpted by
Planets

The Sun and roughly 15% of stars are surrounded by dust disks
collisionally replenished by asteroids and comets. Disk structure can
be directly tied to the dynamical influence of more massive bodies
such as planets. For example, planetary perturbations offset the
center of our zodiacal dust disk ~0.01 AU away from the Sun and also
maintain a ~40 AU radius inner edge to our Kuiper Belt. Here we
propose follow-up observation to the first optical detection of
reflected light from dust grains surrounding the nearby star Fomalhaut
using HST/ACS. We find a belt of material between 133 and 158 AU
radius that has a center position offset ~15 AU from the stellar
position, and with a sharp inner edge. A tenuous dust component
interior to the belt is also detected in the southeast. Given
Fomalhaut's proximity to the Sun {7.7 pc}, these images represent the
closest and highest angular resolution view of an extrasolar analog to
our Kuiper Belt. The center of symmetry offset and the sharp inner
edge of Fomalhaut's belt are evidence for planet-mass objects orbiting
the star as predicted by dynamical theory and simulations. We propose
comprehensive follow-up ACS imaging to fully exploit this discovery
and map the disk around its entire circumference with higher
signal-to-noise and at multiple wavelengths. HST/ACS is certainly the
only facility capable of performing this relatively wide field optical
study at high contrast ratios and diffraction-limited resolution. The
Cycle 14 data will provide key measurements of belt width as a
function of azimuth, the scattered light color of the belt versus the
inner dust component, and the azimuthal structure of the belt. These
data will be used to constrain dynamical models of resonances and
shepherding that ultimately elucidate the dynamical properties of
planet-mass objects in the system.

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 10551

Gamma-Ray Bursts from Start to Finish: A Legacy Approach

The progenitors of long-duration GRBs are now known to be massive
stars. This result lends credence to the collapsar model, where a
rotating massive star ends its life leaving a black hole or a highly
magnetized neutron star, and confirms its essential aspects. The focus
of attention now is on the black hole or magnetar engines that power
the bursts. Somehow these engines create the most highly relativistic
and highly collimated outflows that we know of, through mechanisms
that no current theory can explain. These astrophysical laboratories
challenge our understanding of relativistic shocks, of mechanisms for
extracting energy from a black hole, and of how physics works in
extreme conditions. The launch of Swift is bringing us into a new era,
where we can make broadband observations that will enable us to study
these fascinating physical processes. We propose here an ambitious,
comprehensive program to obtain the datasets that will become the
standard that any successful model for the central engine must
explain. This programs leverages the HST observations to the maximum
extent by our commitment of Swift observations, a Large program at the
VLA, and extensive ground-based optical resources. By studying the
engines and searching for jets in a variety of events, this program
will investigate the conditions necessary for the engine and jet
formation itself.

ACS/WFC 10753

An Astrometric Calibration Field Near the Ecliptic Pole

This program will obtain deep ACS astrometry of a Large Magellanic
Cloud star field lying within the planned continuous viewing zone of
the James Webb Space Telescope, which extends to a 5 degree radius
from the Ecliptic pole. To allow a full astrometric solution to be
calculated, controlling for distortions within ACS that may be time
variable over periods of months to years, we will observe our target
field at two distinct roll angles separated by approximately 90
degrees. To help control for large scale distortions, we will "chop"
the observations in at least one roll angle, using offsets of order
one third the ACS field of view.

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.

FGS 10931

Dynamical Masses and Radii of Four White Dwarf Stars

No Abstract added

NIC1/NC2/NC3 10723

Cycle 14 NICMOS dark current, shading profile, and read noise
monitoring program

The purpose of this proposal is to monitor the dark current, read
noise, and shading profile for all three NICMOS detectors throughout
the duration of Cycle 14. This proposal is a slightly modified version
of proposal 10380 of cycle 13 and 9993 of cycle12 that we cut down
some exposure time to make the observation fit within 24 orbits.

NIC2 10906

The Fundamental Plane of Massive Gas-Rich Mergers: II. The QUEST QSOs

We propose deep NICMOS H-band imaging of a carefully selected sample
of 23 local QSOs. This program is the last critical element of a
comprehensive investigation of the most luminous mergers in the nearby
universe, the ultraluminous infrared galaxies {ULIRGs} and the
quasars. This effort is called QUEST: Quasar / ULIRG Evolutionary
STudy. The high-resolution HST images of the QUEST QSOs will
complement an identical set of images on the ULIRG sample obtained
during Cycle 12, an extensive set of ground-based data that include
long-slit NIR spectra from a Large VLT Program, and a large set of
mid-infrared spectra from a Cycle 1 medium-size program with Spitzer.
This unique dataset will allow us to derive with unprecedented
precision structual, kinematic, and activity parameters for a large
unbiased sample of objects spanning the entire ULIRG/QSO luminosity
function. These data will refine the fundamental plane of massive
gas-rich mergers and enable us to answer the following quesitons: {1}
Do ultraluminous mergers form elliptical galaxies, and in particular,
giant ellipticals? {2} Do ULIRGs evolve into optical bright QSOs? The
results from this detailed study of massive mergers in the local
universe will be relevant to understanding the basic physical
processes involved in creating massive early-type host on the one
hand, and growing/feeding embedded massive black holes on the other,
in major galaxy mergers. This is an important question since 50% of
cosmic star formation at high-z and most of the big BHs appear to be
formed in this process.

WFPC2 10745

WFPC2 CYCLE 14 INTERNAL MONITOR

This calibration proposal is the Cycle 14 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{both gain 7 and gain 15 -- to test stability of gains and bias
levels}, a test for quantum efficiency in the CCDs, and a monitor for
possible buildup of contaminants on the CCD windows. These also
provide raw data for generating annual super-bias reference files for
the calibration pipeline.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

#10358 GSACQ(2,1,2) failed, Search Radius Limit Exceeded on FGS 2 @
192/2203z

GSACQ(2,1,2) at 192/21:58:32 failed due to Search Radius Limit
Exceeded on FGS 2 at 22:03:11. One 486 status buffer message A05 (FGS
Coarse Track failed- Search Radius Limit exceeded) was received. OBAD
at 21:53:22 prior to GSACQ had total RSS attitude error correction of
18.09 arcseconds. Observations affected: ACS 84 to 86.

COMPLETED OPS REQUEST:
#17820-0 Dump ACS Error Log @ 192/1403z
#17821-0 Genslew for proposal 10598 - slot 1 @ 192/1908z
#17822-0 Genslew for proposal 10598 - slot 2 @ 192/1910z
#17823-0 Genslew for proposal 10598 - slot 3 @ 192/1911z
#17824-0 Genslew for proposal 10598 - slot 4 @ 192/1912z
#17825-0 Genslew for proposal 10598 - slot 5 @ 192/1913z
#17826-0 Genslew for proposal 10598 - slot 6 @ 192/1914z
#17827-0 Genslew for proposal 10598 - slot 7 @ 192/1915z
#17828-0 Genslew for proposal 10598 - slot 8 @ 192/1916z
#17818-0 Battery 3 Capacity Test Script & 5 Battery Pressure
Limit COP (thru step 18) @ 192/2134z

COMPLETED OPS NOTES:
#1504-0 Change JERRCNT Limit @ 192/1406z

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 5 4 192/2158z (HSTAR 10358)
FGS REacq 7 7
OBAD with Maneuver 20 20

SIGNIFICANT EVENTS:

Battery 3 Capacity Test Flash Report #1

Commanding for the Battery 3 Capacity Test started as scheduled on DOY
192/1205 GMT (07/11 at 8:05 am) with setting the Battery Pressure Test
for a 5-battery system. Battery 3 was taken off-line and discharged on
the first opportunity at 1228 GMT (07/11 at 8:28 am). Following
completion of the discharge, Battery 3 will be placed back on-line in
hardware during orbit night. Following its recovery period, Battery 3
will be placed back on-line in FSW on 195/1400 GMT (07/14 at 10:00
am).

Battery 3 Capacity Test Flash Report #2

The battery 3 high-rate discharge terminated 192/2134 GMT (07/11 at
5:34 pm). The low rate discharge is now in progress and is expected to
terminate at approximately 194/1200 (Thursday, 7/13 at 8am).