Daily Report #4573

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4573

PERIOD COVERED: UT March 21,22,23, 2008 (DOY 081,082,083)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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 11334

NICMOS Cycle 16 Spectrophotometry

Observation of the three primary WD flux standards must be repeated to
refine the NICMOS absolute calibration and monitor for sensitivity
degradation. So far, NICMOS grism spectrophotometry is available for only
~16 stars with good STIS spectra at shorter wavelengths. There are more in
the HST CALSPEC standard star data base with good STIS spectra that would
also become precise IR standards with NICMOS absolute SED measurements.
Monitoring the crucial three very red stars (M, L, T) for variability and
better S/N in the IR. Apparent variability was discovered at shorter
wavelengths during the ACS cross-calibration work that revealed a ~2%
discrepancy of the cool star fluxes with respect to the hot primary WD
standards. About a third of these stars are bright enough to do in one
orbit, the rest require 2 orbits.

WFPC2 11233

Multiple Generations of Stars in Massive Galactic Globular Clusters

This is a follow-up to recent HST imaging of NGC 2808, which discovered that
its main sequence is triple, with three well-separated parallel branches
{Fig.~1}. Along with the double MS of Omega Centauri, this challenges the
long-held paradigm that globular clusters are simple, single stellar
populations. The cause of this main sequence multiplicity in both clusters
is likely to be differences in helium abundance, which could play a
fundamental role in the understanding of stellar populations. We propose to
image seven more of the most massive globular clusters, to examine their
main sequences for indications of splitting.

NIC2 11219

Active Galactic Nuclei in nearby galaxies: a new view of the origin of the
radio-loud radio-quiet dichotomy?

Using archival HST and Chandra observations of 34 nearby early-type galaxies
{drawn from a complete radio selected sample} we have found evidence that
the radio-loud/radio-quiet dichotomy is directly connected to the structure
of the inner regions of their host galaxies in the following sense: [1]
Radio-loud AGN are associated with galaxies with shallow cores in their
light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep
cusps. Since the brightness profile is determined by the galaxy's evolution,
through its merger history, our results suggest that the same process sets
the AGN flavour. This provides us with a novel tool to explore the
co-evolution of galaxies and supermassive black holes, and it opens a new
path to understand the origin of the radio-loud/radio-quiet AGN dichotomy.
Currently our analysis is statistically incomplete as the brightness profile
is not available for 82 of the 116 targets. Most galaxies were not observed
with HST, while in some cases the study is obstructed by the presence of
dust features. We here propose to perform an infrared NICMOS snapshot survey
of these 82 galaxies. This will enable us to i} test the reality of the
dichotomic behaviour in a substantially larger sample; ii} extend the
comparison between radio-loud and radio-quiet AGN to a larger range of
luminosities.

FGS 11213

Distances to Eclipsing M Dwarf Binaries

We propose HST FGS observations to measure accurate distances of 5 nearby M
dwarf eclipsing binary systems, from which model-independent luminosities
can be calculated. These objects have either poor or no existing parallax
measurements. FGS parallax determinations for these systems, with their
existing dynamic masses determined to better than 0.5%, would serve as
model-independent anchor points for the low-mass end of the mass-luminosity
diagram.

FGS 11211

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a useful
result, judged by the over ten refereed citations each year since. It is,
however, unsatisfactory to have the direct, parallax-based, distance scale
of Population II variables based on a single star. We propose, therefore, to
obtain the parallaxes of four additional RR Lyrae stars and two Population
II Cepheids, or W Vir stars. The Population II Cepheids lie with the RR
Lyrae stars on a common K-band Period-Luminosity relation. Using these
parallaxes to inform that relationship, we anticipate a zero-point error of
0.04 magnitude. This result should greatly strengthen confidence in the
Population II distance scale and increase our understanding of RR Lyrae star
and Pop II Cepheid astrophysics.

FGS 11210

The Architecture of Exoplanetary Systems

Are all planetary systems coplanar? Concordance cosmogony makes that
prediction. It is, however, a prediction of extrasolar planetary system
architecture as yet untested by direct observation for main sequence stars
other than the Sun. To provide such a test, we propose to carry out FGS
astrometric studies on four stars hosting seven companions. Our
understanding of the planet formation process will grow as we match not only
system architecture, but formed planet mass and true distance from the
primary with host star characteristics for a wide variety of host stars and
exoplanet masses. We propose that a series of FGS astrometric observations
with demonstrated 1 millisecond of arc per-observation precision can
establish the degree of coplanarity and component true masses for four
extrasolar systems: HD 202206 {brown dwarf+planet}; HD 128311
{planet+planet}, HD 160691 = mu Arae {planet+planet}, and HD 222404AB =
gamma Cephei {planet+star}. In each case the companion is identified as such
by assuming that the minimum mass is the actual mass. For the last target, a
known stellar binary system, the companion orbit is stable only if coplanar
with the AB binary orbit.

WFPC2 11207

Star Formation in the Perseus Cluster Cooling Flow

We propose to obtain high resolution, UV/optical imaging of the "accretion
populations" in the massive cooling flow of the Perseus cluster of galaxies.
New GALEX observations show that the dominant galaxy in this nearby cluster,
NGC 1275, has an extended network of UV-bright populations apparently formed
recently from the intracluster gas. Cluster cooling flows are the most
prominent of the environments where we can readily observe the cycle of gas
accretion, star formation, and feedback from active nuclei that is thought
to play a central role in the formation and evolution of galaxies. Because
they can be readily age-dated, the accretion populations help to trace the
sequence of exchange of material between galaxies and the intracluster
medium. The ACS/SBC and WFPC2/PC cameras offer the highest spatial
resolution and best panchromatic performance available to map the spatial
and age distribution of the accretion populations and their relationship to
radio-emitting plasma and the hot intracluster gas.

WFPC2 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still
largely an open problem in cosmology: how does the Universe evolve from
large linear scales dominated by dark matter to the highly non-linear scales
of galaxies, where baryons and dark matter both play important, interacting,
roles? To understand the complex physical processes involved in their
formation scenario, and why they have the tight scaling relations that we
observe today {e.g. the Fundamental Plane}, it is critically important not
only to understand their stellar structure, but also their dark-matter
distribution from the smallest to the largest scales. Over the last three
years the SLACS collaboration has developed a toolbox to tackle these issues
in a unique and encompassing way by combining new non-parametric strong
lensing techniques, stellar dynamics, and most recently weak gravitational
lensing, with high-quality Hubble Space Telescope imaging and VLT/Keck
spectroscopic data of early-type lens systems. This allows us to break
degeneracies that are inherent to each of these techniques separately and
probe the mass structure of early-type galaxies from 0.1 to 100 effective
radii. The large dynamic range to which lensing is sensitive allows us both
to probe the clumpy substructure of these galaxies, as well as their
low-density outer haloes. These methods have convincingly been demonstrated,
by our team, using smaller pilot-samples of SLACS lens systems with HST
data. In this proposal, we request observing time with WFPC2 and NICMOS to
observe 53 strong lens systems from SLACS, to obtain complete multi-color
imaging for each system. This would bring the total number of SLACS lens
systems to 87 with completed HST imaging and effectively doubles the known
number of galaxy-scale strong lenses. The deep HST images enable us to fully
exploit our new techniques, beat down low-number statistics, and probe the
structure and evolution of early-type galaxies, not only with a uniform
data-set an order of magnitude larger than what is available now, but also
with a fully coherent and self-consistent methodological approach!

WFPC2 11198

Pure Parallel Imaging in the NDWFS Bootes Field

The NOAO Deep-Wide Field Survey {NDWFS} Bootes field is the target of one of
the most extensive multiwavelength campaigns in astronomy. In addition to
ground-based optical and near-infrared imaging, deep radio mapping, and
extensive spectroscopy, this entire region has been imaged by the Chandra,
Spitzer {IRAC and MIPS}, and GALEX missions. Robust photometric redshifts
{calibrated using over 20,000 spectroscopic redshifts} exist for all sources
brighter than R=24.5 or than 13 uJy at 4.5 microns. To enhance the value of
this data set, we propose pure parallel observations for all approved Cycle
16 programs in this region that lack coordinated parallel observations. The
primary aim of this program will be to provide a database useful for the
broad range of science programs underway in this region.

NIC3 11195

Morphologies of the Most Extreme High-Redshift Mid-IR-luminous Galaxies II:
The `Bump' Sources

The formative phase of some of the most massive galaxies may be extremely
luminous, characterized by intense star- and AGN-formation. Till now, few
such galaxies have been unambiguously identified at high redshift, and thus
far we have been restricted to studying the low-redshift ultraluminous
infrared galaxies as possible analogs. We have recently discovered a sample
of objects which may indeed represent this early phase in galaxy formation,
and are undertaking an extensive multiwavelength study of this population.
These objects are optically extremely faint {R26} but nevertheless bright
at mid-infrared wavelengths {F[24um] 0.5 mJy}. Mid-infrared spectroscopy
with Spitzer/IRS reveals that they have redshifts z~2, implying luminosities
~1E13 Lsun. Their mid-IR SEDs fall into two broad, perhaps overlapping,
categories. Sources with brighter F[24um] exhibit power-law SEDs and SiO
absorption features in their mid-IR spectra characteristic of AGN, whereas
those with fainter F[24um] show a "bump" characteristic of the redshifted
1.6um peak from a stellar population, and PAH emission characteristic of
starformation. We have begun obtaining HST images of the brighter sources in
Cycle 15 to obtain identifications and determine kpc-scale morphologies for
these galaxies. Here, we aim to target the second class {the "bump" sources}
with the goal of determining if these constitute morphologically different
objects, or simply a "low-AGN" state of the brighter class. The proposed
observations will help us determine whether these objects are merging
systems, massive obscured starbursts {with obscuration on kpc scales!} or
very reddened {locally obscured} AGN hosted by intrinsically low-luminosity
galaxies.

WFPC2 11184

Imaging the Shock Precursor in Tycho's SNR

Cosmic ray acceleration in supernova remnant shocks requires shock
precursors where particles are trapped by plasma turbulence. The precursors
also heat and compress the upstream gas, producing H alpha emission and
affecting line profiles. We propose to image the brightest non-radiative
shock in Tycho's SNR to measure the brightness and width of the precursor.
These measurements will constrain 2 key parameters in cosmic ray
acceleration models, and they will improve the accuracy of shock speed and
electron-ion equilibration derived from H alpha profiles.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of
Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens a
window into dynamical conditions in the protoplanetary disk where they
formed as well as the history of subsequent events which sculpted the outer
Solar System and emplaced them onto their present day heliocentric orbits.
To date, at least 47 TNBs have been discovered, but only about a dozen have
had their mutual orbits and separate colors determined, frustrating their
use to investigate numerous important scientific questions. The current
shortage of data especially cripples scientific investigations requiring
statistical comparisons among the ensemble characteristics. We propose to
obtain sufficient astrometry and photometry of 23 TNBs to compute their
mutual orbits and system masses and to determine separate primary and
secondary colors, roughly tripling the sample for which this information is
known, as well as extending it to include systems of two near-equal size
bodies. To make the most efficient possible use of HST, we will use a Monte
Carlo technique to optimally schedule our observations.

NIC3 11153

The Physical Nature and Age of Lyman Alpha Galaxies

In the simplest scenario, strong Lyman alpha emission from high redshift
galaxies would indicate that stellar populations younger than 10 Myrs
dominate the UV. This does not, however, constrain the stellar populations
older than 100 Myrs, which do not contribute to UV light. Also, the Lyman
alpha line can be boosted if the interstellar medium is both clumpy and
dusty. Different studies with small samples have reached different
conclusions about the presence of dust and old stellar populations in Lyman
alpha emitters. We propose HST- NICMOS and Spitzer-IRAC photometry of 35
Lyman-alpha galaxies at redshift 4.5z6.5, in order to determine their
spectral energy distribution {SED} extending through rest-frame optical.
This will allow us to measure accurately {1} The total stellar mass in these
objects, including old stars which may have formed at redshifts {z 8} not
easily probed by any other means. {2} The dust extinction in the rest-frame
UV, and therefore a correction to their present star-formation rates. Taken
together, these two quantities will yield the star-formation histories of
Lyman alpha galaxies, which form fully half of the known galaxies at z=4-6.
They will tell us whether these are young or old galaxies by straddling the
4000A break. Data from NICMOS is essential for these compact and faint
{i=25-26th magnitude AB} high redshift galaxies, which are too faint for
good near-IR photometry from the ground.

NIC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

We aim to determine physical properties of IR luminous galaxies at
0.3z2.7 by requesting coordinated HST/NIC2 and MIPS 70um observations
of a unique, 24um flux-limited sample with complete Spitzer mid-IR
spectroscopy. The 150 sources investigated in this program have S{24um}
0.8mJy and their mid-IR spectra have already provided the majority
targets with spectroscopic redshifts {0.3z2.7}. The proposed 150~orbits of
NIC2 and 66~hours of MIPS 70um will provide the physical measurements of the
light distribution at the rest-frame ~8000A and better estimates of the
bolometric luminosity. Combining these parameters together with the rich
suite of spectral diagnostics from the mid-IR spectra, we will {1} measure
how common mergers are among LIRGs and ULIRGs at 0.3z2.7, and establish if
major mergers are the drivers of z1 ULIRGs, as in the local Universe. {2}
study the co-evolution of star formation and blackhole accretion by
investigating the relations between the fraction of starburst/AGN measured
from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the
current best estimates of the far-IR emission, thus L{bol} for this sample,
and establish if the relative contribution of mid-to-far IR dust emission is
correlated with morphology {resolved vs. unresolved}.

WFPC2 11130

AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge
Paradigm, Part II

The recent progress in the study of central black holes in galactic nuclei
has led to a general consensus that supermassive {10^6-10^9 solar mass}
black holes are closely connected with the formation and evolutionary
history of large galaxies, especially their bulge component. Two outstanding
issues, however, remain unresolved. Can central black holes form in the
absence of a bulge? And does the mass function of central black holes extend
below 10^6 solar masses? Intermediate-mass black holes {10^6 solar masses},
if they exist, may offer important clues to the nature of the seeds of
supermassive black holes. Using the SDSS, our group has successfully
uncovered a new population of AGNs with intermediate-mass black holes that
reside in low-luminosity galaxies. However, very little is known about the
detailed morphologies or structural parameters of the host galaxies
themselves, including the crucial question of whether they have bulges or
not. Surprisingly, the majority of the targets of our Cycle 14 pilot program
have structural properties similar to dwarf elliptical galaxies. The
statistics from this initial study, however, are really too sparse to reach
definitive conclusions on this important new class of black holes. We wish
to extend this study to a larger sample, by using the Snapshot mode to
obtain WFPC2 F814W images from a parent sample of 175 AGNs with
intermediate- mass black holes selected from our final SDSS search. We are
particularly keen to determine whether the hosts contain bulges, and if so,
how the fundamental plane properties of the host depend on the mass of their
central black holes. We will also investigate the environment of this unique
class of AGNs.

WFPC2 11128

Time Scales Of Bulge Formation In Nearby Galaxies

Traditionally, bulges are thought to fit well into galaxy formation models
of hierarchical merging. However, it is now becoming well established that
many bulges formed through internal, secular evolution of the disk rather
than through mergers. We call these objects pseudobulges. Much is still
unknown about pseudobulges, the most pressing questions being: How, exactly,
do they build up their mass? How long does it take? And, how many exist? We
are after an answer to these questions. If pseudobulges form and evolve over
longer periods than the time between mergers, then a significant population
of pseudobulges is hard to explain within current galaxy formation theories.
A pseudobulge indicates that a galaxy has most likely not undergone a major
merger since the formation of the disk. The ages of pseudobulges give us an
estimate for the time scale of this quiescent evolution. We propose to use
24 orbits of HST time to complete UBVIH imaging on a sample of 33 nearby
galaxies that we have observed with Spitzer in the mid-IR. These data will
be used to measure spatially resolved stellar population parameters {mean
stellar age, metallicity, and star formation history}; comparing ages to
star formation rates allows us to accurately constrain the time scale of
pseudobulge formation. Our sample of bulges includes both pseudo- and
classical bulges, and evenly samples barred and unbarred galaxies. Most of
our sample is imaged, 13 have complete UBVIH coverage; we merely ask to
complete missing observations so that we may construct a uniform sample for
studying bulge formation. We also wish to compare the stellar population
parameters to a variety of bulge and global galaxy properties including star
formation rates, dynamics, internal bulge morphology, structure from
bulge-disk decompositions, and gas content. Much of this data set is already
or is being assembled. This will allow us to derive methods of pseudobulge
identification that can be used to accurately count pseudobulges in large
surveys. Aside from our own science goals, we will present this broad set of
data to the community. Thus, we waive proprietary periods for all
observations.

WFPC2 11122

Expanding PNe: Distances and Hydro Models

We propose to obtain repeat narrowband images of a sample of eighteen
planetary nebulae {PNe} which have HST/WFPC2 archival data spanning time
baselines of a decade. All of these targets have previous high
signal-to-noise WFPC2/PC observations and are sufficiently nearby to have
readily detectable expansion signatures after a few years. Our main
scientific objectives are {a} to determine precise distances to these PNe
based on their angular expansions, {b} to test detailed and highly
successful hydrodynamic models that predict nebular morphologies and
expansions for subsamples of round/elliptical and axisymmetric PNe, and {c}
to monitor the proper motions of nebular microstructures in an effort to
learn more about their physical nature and formation mechanisms. The
proposed observations will result in high-precision distances to a healthy
subsample of PNe, and from this their expansion ages, luminosities, CSPN
properties, and masses of their ionized cores. With good distances and our
hydro models, we will be able to determine fundamental parameters {such as
nebular and central star masses, luminosity, age}. The same images allow us
to monitor the changing overall ionization state and to search for the
surprisingly non-homologous growth patterns to bright elliptical PNe of the
same sort seen by Balick & Hajian {2004} in NGC 6543. Non-uniform growth is
a sure sign of active pressure imbalances within the nebula that require
careful hydro models to understand.

NIC3 11120

A Paschen-Alpha Study of Massive Stars and the ISM in the Galactic Center

The Galactic center (GC) is a unique site for a detailed study of a
multitude of complex astrophysical phenomena, which may be common to nuclear
regions of many galaxies. Observable at resolutions unapproachable in other
galaxies, the GC provides an unparalleled opportunity to improve our
understanding of the interrelationships of massive stars, young stellar
clusters, warm and hot ionized gases, molecular clouds, large scale magnetic
fields, and black holes. We propose the first large-scale hydrogen Paschen
alpha line survey of the GC using NICMOS on the Hubble Space Telescope. This
survey will lead to a high resolution and high sensitivity map of the
Paschen alpha line emission in addition to a map of foreground extinction,
made by comparing Paschen alpha to radio emission. This survey of the inner
75 pc of the Galaxy will provide an unprecedented and complete search for
sites of massive star formation. In particular, we will be able to (1)
uncover the distribution of young massive stars in this region, (2) locate
the surfaces of adjacent molecular clouds, (3) determine important physical
parameters of the ionized gas, (4) identify compact and ultra-compact HII
regions throughout the GC. When combined with existing Chandra and Spitzer
surveys as well as a wealth of other multi-wavelength observations, the
results will allow us to address such questions as where and how massive
stars form, how stellar clusters are disrupted, how massive stars shape and
heat the surrounding medium, and how various phases of this medium are
interspersed.

WFPC2 11083

The Structure, Formation and Evolution of Galactic Cores and Nuclei

A surprising result has emerged from the ACS Virgo Cluster Survey {ACSVCS},
a program to obtain ACS/WFC gz imaging for a large, unbiased sample of 100
early-type galaxies in the Virgo Cluster. On subarcsecond scales {i.e.,
0.1"-1"}, the HST brightness profiles vary systematically from the
brightest giants {which have nearly constant surface brightness cores} to
the faintest dwarfs {which have compact stellar nuclei}. Remarkably, the
fraction of galaxy mass contributed by the nuclei in the faint galaxies is
identical to that contributed by supermassive black holes in the bright
galaxies {0.2%}. These findings strongly suggest that a single mechanism is
responsible for both types of Central Massive Object: most likely internally
or externally modulated gas inflows that feed central black holes or lead to
the formation of "nuclear star clusters". Understanding the history of gas
accretion, star formation and chemical enrichment on subarcsecond scales has
thus emerged as the single most pressing question in the study of nearby
galactic nuclei, either active or quiescent. We propose an ambitious HST
program {199 orbits} that constitutes the next, obvious step forward:
high-resolution, ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W} imaging
for the complete ACSVCS sample. By capitalizing on HST's unique ability to
provide high-resolution images with a sharp and stable PSF at UV and IR
wavelengths, we will leverage the existing optical HST data to obtain the
most complete picture currently possible for the history of star formation
and chemical enrichment on these small scales. Equally important, this
program will lead to a significant improvement in the measured structural
parameters and density distributions for the stellar nuclei and the
underlying galaxies, and provide a sensitive measure of "frosting" by young
stars in the galaxy cores. By virtue of its superb image quality and stable
PSF, NICMOS is the sole instrument capable of the IR observations proposed
here. In the case of the WFPC2 observations, high-resolution UV imaging {
0.1"} is a capability unique to HST, yet one that could be lost at any time.

WFPC2 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 distinguished 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.

WFPC2 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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11228 - GSAcq (1,2,2) failed to RGA Hold (Gyro Hold)

At 082/00:15:25, GSAcq (1,2,2) scheduled at 082/00:11:16-00:18:32 failed to
RGA Hold (Gyro Control) due QSTOP flag on FGS 1. Received QF1STOPF & QSTOP
stop flags on FGS1. No 486 STB messages noted. Pre-acquisition OBAD #1 RSS
value = 2128.48 arc-seconds. Pre acquisition OBAD #2 RSS value = 9.03
arc-seconds. Post-acquisition OBAD MAP was not scheduled. REAcq (1,2,2) at
082/01:48:35 was successful.

11229 - REacq(2,3,3) Failed to RGA Hold

During LOS REacq(2,3,3) scheduled at 084/06:09:24 failed to RGA Hold. At AOS
no flags were set. OBAD1 showed errors of V1= -292.59, V2=-444.58, V3
=139.19 and RSS= 550.13. OBAS2 showed errors of V1=79.07, V2=68.78, V3=30.91
and RSS = 109.26 .

11230 - REacq(2,3,3) Failed to Gyro Hold

REacq(2,3,3) scheduled at 084/07:45:16 failed at 07:50:08 due to search
radius limit exceeded on FGS 2. OBAD2 showed errors of V1=3.39, V2=0.28,
V3=-0.40, and RSS=3.42.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 26 25
FGS REacq 17 15
OBAD with Maneuver 76 76

SIGNIFICANT EVENTS: (None)