Daily # 4132

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4132

PERIOD COVERED: UT June 09,10,11, 2006 (DOY 160,161,162)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

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 10752

Cycle 14 Focus Monitor

The focus of HST is measured primarily with ACS/HRC over full CVZ
orbits to obtain accurate mean focus values via a well sampled
breathing curve. Coma and astigmatism are also determined from the
same data in order to further understand orbital effects on image
quality and optical alignments. To monitor the stability of ACS to
WFPC2 relative focii, we've carried over from previous focus monitor
programs parallel observations taken with the two cameras at suitable
orientations of previously observed targets, and interspersed them
with the HRC CVZ visits.

WFPC2 10749

Earth Flats

This proposal monitors flatfield stability. This proposal obtains
sequences of Earth streak flats to construct high quality flat fields
for the WFPC2 filter set. These flat fields will allow mapping of the
OTA illumination pattern and will be used in conjuction with previous
internal and external flats to generate new pipeline superflats. These
Earth flats will complement the Earth flat data obtained during cycles
4-13.

ACS/WFC 10740

Absolute Photometric & Spectrophometric Calibration

This program has several goals: 1.}Verify repeatability of the ACS
instrumentation on a single bright star to +/-0.2%. 2.}Determine any
shift in the filter bandpasses since the preflight lab measurements.
3.}Determine the relative magnitude of the 3 primary WD calibrators to
0.1%. 4.}Refine the sensitivity calibration of the CCD prism and
grisms at field center and determine the repeatability accuracy of
this calibration. 5.}Determine the level of variability of the three
HST red standard stars: VB-8 {M7}, 2M0038+18 {L3.5} and 2M0559-14
{T5}, and also measure their short wavelength {7000A} fluxes.
6.}Cross calibrate with a faint STIS and NICMOS standard WD and solar
analog star.

ACS/WFC 10732

ACS internal CTE monitor

The charge transfer efficiency {CTE} of the ACS CCD detectors will
decline as damage due to on-orbit radiation exposure accumulates. This
degradation will be closely monitored at regular intervals, because it
is likely to determine the useful lifetime of the CCDs. All the data
for this program is acquired using internal targets {lamps} only, so
all of the exposures should be taken during Earth occultation time
{but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

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.

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.

ACS/WFC 10626

A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to
z = 0.9

We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy
clusters at 0.3 z 0.9 from the Red Sequence Cluster Survey {RCS}.
An examination of the galaxian light in the brightest cluster
galaxies, coupled with a statistical analysis of the strong-lensing
properties of the sample, will allow us to contrain the evolution of
both the baryonic and dark mass in cluster cores, over an
unprecedented redshift range and sample size. In detail, we will use
the high- resolution ACS images to measure the metric {10 kpc/h}
luminosity and morphological disturbances around the brightest
clusters galaxies, in order to calibrate their accretion history in
comparison to recent detailed simulations of structure formation in
cluster cores. These images will also yield a well-defined sample of
arcs formed by strong lensing by these clusters; the frequency and
detailed distribution {size, multiplicity, redshifts} of these strong
lens systems sets strong constraints on the total mass content {and
its structure} in the centers of the clusters. These data will also be
invaluable in the study of the morphological evolution and properties
of cluster galaxies over a significant redshift range. These analyses
will be supported by extensive ongoing optical and near-infrared
imaging, and optical spectroscopy at Magellan, VLT and Gemini
telescopes, as well as host of smaller facilities.

FGS 10611

Precise Distances to Nearby Planetary Nebulae

We propose to carry out astrometry with the FGS to obtain accurate and
precise distances to four nearby planetary nebulae. In 1992, Cahn et
al. noted that ``The distances to Galactic planetary nebulae remain a
serious, if not THE most serious, problem in the field, despite
decades of study.'' Twelve years later, the same statement still
applies. Because the distances to planetary nebulae are so uncertain,
our understanding of their masses, luminosities, scale height, birth
rate, and evolutionary state is severely limited. To help remedy this
problem, HST astrometry can guarantee parallaxes with half the error
of any other available approach. These data, when combined with
parallax measurements from the USNO, will improve distance
measurements by more than a factor of two, producing more accurate
distances with uncertainties that are of the order of ~6%. Lastly,
most planetary nebula distance scales in the literature are
statistical. They require several anchor points of known distance in
order to calibrate their zero point. Our program will provide "gold
standard" anchor points by the end of 2006, a decade before any
anticipated results from future space astrometry missions.

ACS/HRC 10602

A Complete Multiplicity Survey of Galactic O2/O3/O3.5 Stars with ACS

Massive stars are preferentially formed in compact multiple systems
and clusters and many of them remain spatially unresolved to date,
even in our Galaxy. This has hindered the determination of the stellar
upper mass limit. The lack of an accurate knowledge of the
multiplicity of massive stars can also introduce biases in the
calculation of the IMF at its high-mass end. We have recently used
ACS/HRC to resolve HD 93129 A, the earliest O-type star known in the
Galaxy, into a 55 mas binary. We propose here to extend that work into
a complete multi-filter ACS imaging survey of all {20} known
O2/O3/O3.5 Galactic stars to characterize the multiplicity of the most
massive stars. The data will be combined with existing FGS
observations to explore as large a parameter range as possible and to
check for consistency. We will also derive the IMF of each system
using a crowded-field photometry package and processing the data with
CHORIZOS, a code that can derive stellar temperatures, extinctions,
and extinction laws from multicolor photometry.

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 10588

The Host Galaxies of Post-Starburst Quasars

We propose to use ACS to conduct a snapshot imaging survey of
post-starburst quasars now being discovered in signficant numbers by
the Sloan Digital Sky Survey. Post-starburst quasars are broad-lined
AGN that also possess Balmer jumps and high-n Balmer absorption lines
indicative of luminous stellar populations on order of 100 Myr old.
These objects, representing a few percent of the z 0.5 quasar
population, may be an evolutionary stage in the transition of
ultraluminous infrared galaxies into normal quasars, or a type of
galaxy interaction that triggers both star formation and nuclear
activity. These sources may also illustrate how black hole mass/bulge
mass correlations arise. Ground-based imaging of individual
poststarburst quasars has revealed merger remnants, binary systems,
and single point sources. Our ACS snapshots will enable us to
determine morphologies and binary structure on sub-arcsecond scales
{surely present in the sample}, as well as basic host galaxy
properties. We will be looking for relationships among morphology,
particularly separation of double nuclei, the starburst age, the
quasar black hole mass and accretion rate, that will lead to an
understanding of the triggering activity and mutual evolution. This
project will bring quantitative data and statistics to the previously
fuzzy and anecdotal topic of the "AGN-starburst connection" and help
test the idea that post-starburst quasars are an early evolutionary
stage of normal quasars.

ACS/WFC 10565

The outermost globular cluster of M31

We have recently identified a previously unknown globular cluster in
the M31 system that is located at 4 degrees from the center of the
galaxy and in proximity {14 arcmin apart} of the major axis. This is
by far the most remote M31 cluster presently known, more than 1 degree
farther than any other recognized cluster. Low resolution spectra have
confirmed that the object is member of M31 and its line-of-sight
velocity lie approximately on the extrapolation of the HI rotation
curve of the galaxy. The projected position and kynematics of the
cluster strongly suggest that it may be associated with the disc of
M31. If this hypothesis will be confirmed it would imply that the
stellar disc of M31 extends out to ~55 kpc {the projected
galactocentric distance of the newly discovered object} with far
reaching consequences on our ideas of the formation of galactic discs.
We propose ACS/WFC observations aimed at obtaining the Color Magnitude
Diagram of the cluster and its surroundig field to constrain the age
and metallicity of both populations. This will provide direct
indications on the actual extension and epoch of formation of the M31
disc as well as a deep insight in the stellar content of a remote
region of this galaxy that has not been studied before.

ACS/HRC 10556

Neutral Gas at Redshift z=0.5

Damped Lyman-alpha systems {DLAs} are used to track the bulk of the
neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy,
they could only be studied from the ground at redshifts z1.65.
However, HST has now permitted us to discover 41 DLAs at z1.65 in our
previous surveys. Followup studies of these systems are providing a
wealth of information about the evolution of the neutral gas phase
component of the Universe. But one problem is that these 41
low-redshift systems are spread over a wide range of redshifts
spanning nearly 70% of the age of the Universe. Consequently, past
surveys for low-redshift DLAs have not been able to offer very good
precision in any small redshift regime. Here we propose an ACS-HRC-
PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7]
which we estimate will permit us to discover another 41 DLAs. This
will not only allow us to double the number of low-redshift DLAs, but
it will also provide a relatively high-precision regime in the
low-redshift Universe that can be used to anchor evolutionary studies.
Fortunately DLAs have high absorption equivalent width, so
ACS-HRC-PR200L has high-enough resoultion to perform this proposed
MgII-selected DLA survey.

ACS/HRC 10555

A Search for Satellites Around Kuiper Belt Objects Which Exhibit High
Angular Momentum

We propose to use the HST to search for satellites around Kuiper Belt
Objects which have large amplitude, fast rotational light curves.
Large main belt asteroids with similar light curve characteristics
have been found to have near an 80 percent companion rate. This is
over an order of magnitude more than the companion rate of main belt
asteroids in general. The satellites were probably formed during the
process which imparted the high angular momentum on the primary
object. To date five Kuiper Belt objects exhibit high angular momentum
through their rotational light curves. Two of them have been observed
with STIS on the HST and one was found to be a binary. We request
three orbits with HST/ACS in order to obtain deep high resolution
images of the other three Kuiper Belt objects that have large
amplitudes and fast rotations. In addition, we request one orbit to
reobserve the other KBO which didn't have a satellite detection in
order to obtain deeper and better resolution images than the first
observations. Finding binaries is important not only to understand the
processes which created the high angular momentum of the primary but
also in determining the bulk densities and collisional histories of
the objects.

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 10550

The Nature of LSB galaxies revealed by their Globular Clusters

Low Surface Brightness {LSB} galaxies encompass many of the extremes
in galaxy properties. Their understanding is essential to complete our
picture of galaxy formation and evolution. Due to their historical
under-representation on galaxy surveys, their importance to many areas
of astronomy has only recently began to be realized. Globular clusters
are superb tracers of the formation histories of galaxies and have
been extensively used as such in high surface brightness galaxies. We
propose to investigate the nature of massive LSB galaxies by studying
their globular cluster systems. No globular cluster study has been
reported for LSB galaxies to date. Yet, both the presence or absence
of globular clusters set very strong constraints on the conditions
prevailing during LSB galaxy formation and evolution. Both in dwarf
and giant high surface brightness {HSB} galaxies, globular clusters
are known to form as a constant fraction of baryonic mass. Their
presence/absence immediately indicates similarities or discrepancies
in the formation and evolution conditions of LSB and HSB galaxies. In
particular, the presence/absence of metal-poor halo globular clusters
infers similarities/differences in the halo formation and assembly
processes of LSB vs. HSB galaxies, while the presence/absence of
metal-rich globular clusters can be used to derive the occurrence and
frequency of violent events {such as mergers} in the LSB galaxy
assembly history. Two band imaging with ACS will allow us to identify
the globular clusters {just resolved at the selected distance} and to
determine their metallicity {potentially their rough age}. The
composition of the systems will be compared to the extensive census
built up on HSB galaxies. Our representative sample of six LSB
galaxies {cz 2700 km/s} are selected such, that a large system of
globular clusters is expected. Globular clusters will constrain phases
of LSB galaxy formation and evolution that can currently not be probed
by other means. HST/ACS imaging is the only facility capable of
studying the globular cluster systems of LSB galaxies given their
distance and relative scarcity.

ACS/WFC/HRC 10536

What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey

Essentially all planetary nebulae {PNs} are aspherical, whereas the
mass-loss envelopes of AGB stars are strikingly spherical. Our
previous SNAPshot surveys of a morphologically unbiased sample of
pre-planetary nebulae {PPNs} -- objects in transition between the AGB
and PN evolutionary phases -- show that roughly half our observed
targets are resolved, with bipolar or multipolar morphologies.
Spectroscopic observations of our sample confirm that these objects
have not yet evolved into planetary nebulae. Thus, the transformation
from spherical to aspherical geometries has already fully developed by
the time these dying stars have become PPNs. Although our current
studies have yielded exciting results, they are limited in two
important ways -- {1} the number of well-resolved objects is still
small {18}, and the variety of morphologies observed relatively
multitudinous, hence no clear trends can yet be established between
morphology and other source properties {e.g., near-IR, far-IR colors,
stellar spectral type, envelope mass}, and {2} the current samples are
strongly biased towards small PPNs, as inferred from their low
60-to-25 micron flux ratios [R{60/25}1]. However, the prototype of
objects with R{60/25}1, the Frosty Leo Nebula, has a puzzlingly large
post-AGB age {almost 10^4 yr} and a fairly cool central star, very
different from the expectations of single-star stellar evolutionary
models. A proposed, but still speculative, hypothesis for such objects
is that the slow evolution of the central star is due to backflow of
material onto the mass-losing star, retarding its evolution towards
the PN phase. This hypothesis has significant consequences for both
stellar and nebular evolution. We therefore propose a survey of PPNs
with R{60/25}1 which is heavily weighted towards the discovery of
such "stalled PPNs". Supporting kinematic observations using long-slit
optical spectroscopy {with the Keck}, millimeter and radio
interferometric observations {with OVRO, VLA & VLBA} are being
undertaken. The results from this survey {together with our previous
work} will allow us to draw general conclusions about the complex
mass-outflow processes affecting late stellar evolution, and will
provide crucial input for theories of post-AGB stellar evolution. Our
survey will produce an archival legacy of long-standing value for
future studies of dying stars.

NIC2/ACS/WFC/WFPC2 10532

Kinematics and morphology of the most massive field disk galaxies at
z1

We propose to obtain 1 orbit NIC-2 images of a sample of the 15 most
massive galaxies found at $1 z 1.3$. These were culled from over
20, 000 Keck spectra collected as part of DEEP and are unique among
high redshift massive galaxy samples in being kinematically selected.
We intend to test whether these potentially very young galaxies are
likely precursors to massive local disks, assuming no further merging.
NIC-2 images provide rest-frame optical morphologies that will show
whether they are normal disky systems or instead more disturbed
looking objects with multiple subcomponents, mergers, peculiar
structure, etc. NIC-2 provides near-IR resolutions sufficient to
enable measurements of bulges and disks subcomponents. The near-IR
will fill a critical gap in the broad-band SED photometry of the
galaxy and its subcomponents to estimate mean stellar ages and stellar
masses and to assess whether old stellar bulges and disks are in place
at that time. Finally, this sample will yield the first statistically
significant results on the $z 1$ evolution of the Tully-Fisher
relation for massive galaxies. In addition, we propose parallel
observations with ACS WFC {V and I bands} and WFPC2 {I-band}. These
will target up to 700 galaxies at redshifts 0.7 ... 1.2 for which the
DEEP2 survey has obtained precision redshifts and high-resolution
kinematic data. The added HST morphology and color information will
allow a variety of detailed studies on dynamical, structural, and
photometric evolution of galaxies.

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.

ACS/HRC 10525

Characterizing the Near-UV Environment of M Dwarfs: Implications for
Extrasolar Planetary Searches and Astrobiology

We propose SNAP observations with the ACS HRC PR200L prism, designed
to measure the near ultraviolet emission in a sample of 107 nearby M
dwarfs. The sample spans the mass range from 0.1 - 0.6 solar masses
{temperature range 2200K - 4000K} where the UV energy distributions
vary widely between active and inactive stars. The strength and
distribution of this UV emission can have critical consequences for
the atmospheres of attendant planets. Our proposed observations will
provide desperately needed constraints on models of the habitability
zone and the atmospheres of possible terrestrial planets orbiting M
dwarf hosts, and will be used to sharpen TPF target selection. In
addition, the NUV data will be used in conjunction with existing
optical, FUV and X-ray data to constrain a new generation of M dwarf
atmospheric models, and to explore unanswered questions regarding the
dynamo generation and magnetic heating in these low-mass stars.

ACS/HRC/WFC 10514

Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have
relatively fragile test particles which can be used as tracers of the
early dynamical evolution of the outer Solar System. We propose a
Snapshot program using the ACS/HRC that has a potential discovery
efficiency an order of magnitude higher than the HST observations that
have already discovered the majority of known transneptunian binaries.
By more than doubling the number of observed objects in dynamically
hot and cold subpopulations we will be able to answer, with
statistical significance, the question of whether these groups differ
in the abundance of binaries as a result of their particular dynamical
paths into the Kuiper Belt. Today's Kuiper Belt bears the imprints of
the final stages of giant-planet building and migration; binaries may
offer some of the best preserved evidence of that long-ago era.

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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10300 - GSAcq(2,1,1) failed to RGA Control @ 160/1904z

At acquisition of signal 160/19:28:00, GSAcq(2,1,1)scheduled for
160/19:04:17 - 19:12:22 was observed to have failed to RGA Hold due to
stop flag (QF2STOPF) on FGS-2. At 160/19:35:53, scan step limit
exceeded flag (QF2SSLEX) was observed. NIC2 Target Acquisition
Observation at 160/19:12:22 failed due to TDF down. Post-acquisition
OBAD/MAP at 160/19:12:21 had (RSS) error correction value of 19.95
arcseconds.

10301 - Loss of Lock @ 162/0820z

GSAcq (1,2,1) scheduled for 162/08:05:30-08:12:49 succeded with SCI
INIT @ 08:10:32. A Type 3 slew was scheduled from 08:12:49-08:20:08.
At 08:20:37 mnemonics QF1STOPF, QF1SSDIF, QF2STOPF, QF2SSDIF, QSTOP
illuminated. The Take Data flag cycled up and down during type T3
slew, ending down @ 08:20:38.

10302 - GSAcq (2,3,2) failed to RGA Control @ 163/0156z

GSAcq (2,3,2) scheduled at 163/01:53:21-02:00:40 failed to RGA control
due to stop flag (QF2STOPF) on FGS-2. OBAD #1: V1 -886.90, V2 3676.85,
V3 -294.25, RSS 3793.73 OBAD #2: V1 -1265, V2 0.25, V3 -11.53, RSS
17.12

COMPLETED OPS REQUEST:
17792-0 - BCT Prep: Adjust VTFE to K1L4 @ 160/1444z

COMPLETED OPS NOTES:
1386-3 - User Class for Quick Updated Proc's (CCS-D) @ 160/1730z
1409-0 - Mnemonic Display Utility Work Around (CCS-D) @ 160/1730z
1484-1 - Set Nominal Battery Temperature Limits @ 160/2116z
1488-0 - Clear NICMOS Error Flag per SI_SE Directive @ 160/2321z
1484-2 - Set Nominal Battery Temperature Limits @ 161/0237z


SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 31 29 (HSTAR 10300)
(HSTAR
10302)
FGS REacq 12 12
OBAD with Maneuver 86 86
LOSS of LOCK (HSTAR
10301)

SIGNIFICANT EVENTS:

VTFE Curve Adjustment Flash Report:

With battery temperatures low, EPS SEs raised the VTFE back to K1L4 in
prep for the upcoming Battery 1 Capacity Test scheduled for June 13th.
This commanding was executed successfully via the SSM486 FSW IP-109:
Battery Capacity and Elevated VTFE Curve SPS Macros Installation and
Usage in Ops Request 17792 on DOY 2006/160 at 14: