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Daily Report #4520

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Old January 7th 08, 02:17 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report #4520

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** # 4520

PERIOD COVERED: UT January 04,05,06, 2008 (DOY 004,005,006)


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 DARKs. 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/SBC 11309

Chemical Composition of an Exo-Neptune

The recent discovery that the Neptune-like exoplanet GJ 436 b transits
its host star has presented us the first chance to observationally
study ice giant formation beyond our solar system {Gillon et al.
2007}. Using Directors Discretionary time, we propose to obtain a
high-precision light curve of the GJ 436 b transit with the FGS in
order to improve the current radius determination for this planet.
Measuring a precise radius for GJ 436 b will allow us to ascertain
whether the planet has a pure water vapor or H/He envelope like Uranus
and Neptune. Knowing this will constrain its formation and evolution
and help place our own solar system ice giants in a broader context.
Additionally, a precise radius for GJ 436 b will be a necessity for
interpreting the certain follow-up observations of this unique

FGS 11299

Calibrating the Mass-Luminosity Relation at the End of the Main

We propose to use HST-FGS1R to finish calibrating the mass-luminosity
relation for stars less massive than 0.5 Msun, with special emphasis
on objects near the stellar/substellar border. Our goals are to
determine Mv values to 0.05 magnitude and masses to 5%, and thereby
build the fundamental database of stellar masses that we will use to
test theoretical models as never before. This program uses the
combination of HST- FGS3/FGS1R at optical wavelengths, historical
infrared speckle data, ground-based parallax work, metallicity
studies, and radial velocity monitoring to examine nearby,
subarcsecond binary systems. The high precision separation and
position angle measurements with HST-FGS3/FGS1R {to 1 mas in the
separations} for these faint {V = 10-15} targets simply cannot be
equaled by any ground-based technique. As a result of these
measurements, we are deriving high quality luminosities and masses for
the components in the systems, and characterizing their spectral
energy distributions from 0.5 to 2.2 microns. One of the objects, GJ
1245 C with mass 0.074 +/- 0.002 Msun, is the only object known with
an accurate dynamical mass less than 0.10 Msun. The payoff of this
proposal is high because the six systems selected for final
observations in Cycles 15 and 16 have already been resolved during
Cycles 5-13 with HST FGS3/FGS1R and contain most of the reddest
objects for which accurate dynamical masses can be determined.

WFPC2 11297

Reducing Systematic Errors on the Hubble Constant: Metallicity
Calibration of the Cepheid PL Relation

Reducing the systematic errors on the Hubble constant is still of
significance and of immediate importance to modern cosmology. One of
the largest remaining uncertainties in the Cepheid-based distance
scale (which itself is at the foundation of the HST Key Project
determination of H_o) which can now be addressed directly by HST, is
the effect of metallicity on the Cepheid Period-Luminosity relation.
Three chemically distinct regions in M101 will be used to directly
measure and thereby calibrate the change in zero point of the Cepheid
PL relation over a range of metallicities that run from SMC-like,
through Solar, to metallicities as high as the most metal-enriched
galaxies in the pure Hubble flow. ACS for the first time offers the
opportunity to make a precise calibration of this effect which
currently accounts for at least a third of the total systematic
uncertainty on Ho. The calibration will be made in the V and I
bandpasses so as to be immediately and directly applicable to the
entire HST Cepheid-based distance scale sample, and most especially to
the highest-metallicity galaxies that were hosts to the Type Ia
supernovae, which were then used to extend the the distance scale
calibration out to cosmologically significant distances.

WFPC2 11289

SL2S: The Strong Lensing Legacy Survey

Recent systematic surveys of strong galaxy-galaxy lenses {CLASS,
SLACS, GOODS, etc.} are producing spectacular results for galaxy
masses roughly below a transition mass M~10^13 Mo. The observed lens
properties and their evolution up to z~0.2, consistent with numerical
simulations, can be described by isothermal elliptical potentials. In
contrast, modeling of giant arcs in X-ray luminous clusters {halo
masses M ~10^13 Mo} favors NFW mass profiles, suggesting that dark
matter halos are not significantly affected by baryon cooling. Until
recently, lensing surveys were neither deep nor extended enough to
probe the intermediate mass density regime, which is fundamental for
understanding the assembly of structures. The CFHT Legacy Survey now
covers 125 square degrees, and thus offers a large reservoir of strong
lenses probing a large range of mass densities up to z~1. We have
extracted a list of 150 strong lenses using the most recent CFHTLS
data release via automated procedures. Following our first SNAPSHOT
proposal in cycle 15, we propose to continue the Hubble follow-up
targeting a larger list of 130 lensing candidates. These are
intermediate mass range candidates {between galaxies and clusters}
that are selected in the redshift range of 0.2-1 with no a priori
X-ray selection. The HST resolution is necessary for confirming the
lensing candidates, accurate modeling of the lenses, and probing the
total mass concentration in galaxy groups up to z~1 with the largest
unbiased sample available to date.

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 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is
seriously incomplete for systems in the period range from years to
millennia because the radial velocity variations are too small and the
angular separations too close for easy detection. Here we propose to
discover binaries in this observational gap through a Faint Guidance
Sensor SNAP survey of relatively bright targets listed in the Galactic
O Star Catalog. Our primary goal is to determine the binary frequency
among those in the cluster/association, field, and runaway groups. The
results will help us assess the role of binaries in massive star
formation and in the processes that lead to the ejection of massive
stars from their natal clusters. The program will also lead to the
identification of new, close binaries that will be targets of long
term spectroscopic and high angular resolution observations to
determine their masses and distances. The results will also be
important for the interpretation of the spectra of suspected and newly
identified binary and multiple systems.

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 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 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

WFPC2 11171

Confirming Light Echoes from SN 2006X in M100

We propose a minimal investment of spacecraft time to discover and
confirm a light echo from Supernova 2006X in M100, the closest Type Ia
in many years. Our spectroscopic and photometric data indicate that
this SN sits behind a large amount of interstellar dust likely to
produce a strong echo signal. This is one of very few cases where we
will be able to study the three-dimensional environment of a SN Ia in
full detail, and begin to understand how environmental effects play
into the evolutionary and observational factors which influence the
utility of SN Ia as standard candles for probing cosmology. We propose
an efficient program to definitively detect (or not) a light echo of
reasonable signal strength, to confirm that it is an echo by
demonstrating apparent superluminal motion if it exists, to map the
three-dimensional geometry of the reflecting interstellar structures,
and to detail the reflectance properties of the dust which can be used
to constrain its grain size and composition distribution.

WFPC2 11169

Collisions in the Kuiper belt

For most of the 15 year history of observations of Kuiper belt
objects, it has been speculated that impacts must have played a major
role in shaping the physical and chemical characteristics of these
objects, yet little direct evidence of the effects of such impacts has
been seen. The past 18 months, however, have seen an explosion of
major new discoveries giving some of the first insights into the
influence of this critical process. From a diversity of observations
we have been led to the hypotheses that: {1} satellite- forming
impacts must have been common in the Kuiper belt; {2} such impacts led
to significant chemical modification; and {3} the outcomes of these
impacts are sufficiently predictable that we can now find and study
these impact-derived systems by the chemical and physical attributes
of both the satellites and the primaries. If our picture is correct,
we now have in hand for the first time a set of incredibly powerful
tools to study the frequency and outcome of collisions in the outer
solar system. Here we propose three linked projects that would answer
questions critical to the multiple prongs of our hypothesis. In these
projects we will study the chemical effects of collisions through
spectrophotometric observations of collisionally formed satellites and
through the search for additional satellites around primaries with
potential impact signatures, and we will study the physical effects of
impacts through the examination of tidal evolution in proposed impact
systems. The intensive HST program that we propose here will allow us
to fully test our new hypotheses and will provide the ability to
obtain the first extensive insights into outer solar system impact

NIC2 11166

The Mass-dependent Evolution of the Black Hole-Bulge Relations

In the local universe, the masses of giant black holes are correlated
with the luminosities, masses and velocity dispersions of their host
galaxy bulges. This indicates a surprisingly close connection between
the evolution of galactic nuclei (on parsec scales) and of stars on
kpc scales. A key observational test of proposed explanations for
these correlations is to measure how they have evolved over cosmic
time. Our ACS imaging of 20 Seyfert 1 galaxies at z=0.37 showed them
to have smaller bulges (by a factor of 3) for a given central black
hole mass than is found in galaxies in the present-day universe.
However, since all our sample galaxies had black hole masses in the
range 10^8.0--8.5 Msun, we could only measure the OFFSET in black hole
mass to bulge luminosity ratios from the present epoch. By extending
this study to black hole masses another factor of 10 lower, we propose
to determine the full CORRELATION of black hole mass with host galaxy
properties at a lookback time of 4 Gyrs and to test mass-dependency of
the evolution. We have selected 14 Seyfert galaxies from SDSS DR5
whose narrow Hbeta emission lines (and estimated nuclear luminosities)
imply that they have black hole masses around 10^7 Msuns. We will soon
complete our Keck spectroscopic measures of their bulge velocity
dispersions. We need a 1-orbit NICMOS image of each galaxy to separate
its nonstellar luminosity from its bulge and disk. This will allow us
to make the first determination of the full black hole/bulge relations
at z=0.37 (e.g. M-L and M-sigma), as well as a test of whether active
galaxies obey the Fundamental Plane relation at that epoch.

NIC2 11155

Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging
and Polarimetry

We propose to take advantage of the sensitive coronagraphic
capabilities of NICMOS to obtain multiwavelength coronagraphic imaging
and polarimetry of primordial dust disks around young
intermediate-mass stars {Herbig Ae stars}, in order to advance our
understanding of how dust grains are assembled into larger bodies.
Because the polarization of scattered light is strongly dependent on
scattering particle size and composition, coronagraphic imaging
polarimetry with NICMOS provides a uniquely powerful tool for
measuring grain properties in spatially resolved circumstellar disks.
It is widely believed that planets form via the gradual accretion of
planetesimals in gas-rich, dusty circumstellar disks, but the
connection between this suspected process and the circumstellar disks
that we can now observe around other stars remains very uncertain. Our
proposed observations, together with powerful 3-D radiative transfer
codes, will enable us to quantitatively determine dust grain
properties as a function of location within disks, and thus to test
whether dust grains around young stars are in fact growing in size
during the putative planet-formation epoch. HST imaging polarimetry of
Herbig Ae stars will complement and extend existing polarimetric
studies of disks around lower-mass T Tauri stars and debris disks
around older main-sequence stars. When combined with these previous
studies, the proposed research will help us establish the influence of
stellar mass on the growth of dust grains into larger planetesimals,
and ultimately to planets. Our results will also let us calibrate
models of the thermal emission from these disks, a critical need for
validating the properties of more distant disks inferred on the basis
of spectral information alone.

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.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey
of a sample of 125 very X-ray luminous clusters in the redshift range
0.3-0.7. As demonstrated by the 25 snapshots obtained so far in
Cycle14 and Cycle15 these systems frequently exhibit strong
gravitational lensing as well as spectacular examples of violent
galaxy interactions. The proposed observations will provide important
constraints on the cluster mass distributions, the physical nature of
galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set
of optically bright, lensed galaxies for further 8-10m spectroscopy.
All of our primary science goals require only the detection and
characterization of high-surface-brightness features and are thus
achievable even at the reduced sensitivity of WFPC2. Because of their
high redshift and thus compact angular scale our target clusters are
less adversely affected by the smaller field of view of WFPC2 than
more nearby systems. Acknowledging the broad community interest in
this sample we waive our data rights for these observations. Due to a
clerical error at STScI our approved Cycle15 SNAP program was barred
from execution for 3 months and only 6 observations have been
performed to date - reinstating this SNAP at Cycle16 priority is of
paramount importance to reach meaningful statistics.

NIC2 11101

The Relevance of Mergers for Fueling AGNs: Answers from QSO Host

The majority of QSOs are known to reside in centers of galaxies that
look like ellipticals. Numerical simulations have shown that remnants
of galaxy mergers often closely resemble elliptical galaxies. However,
it is still strongly debated whether the majority of QSO host galaxies
are indeed the result of relatively recent mergers or whether they are
completely analogous to inactive ellipticals to which nothing
interesting has happened recently. To address this question, we
recently obtained deep HST ACS images for five QSO host galaxies that
were classified morphologically as ellipticals {GO-10421}. This pilot
study revealed striking signs of tidal interactions such as ripples,
tidal tails, and warped disks that were not detected in previous
studies. Our observations show that at least some "elliptical" QSO
host galaxies are the products of relatively recent merger events
rather than old galaxies formed at high redshift. However, the
question remains whether the host galaxies of classical QSOs are truly
distinct from inactive ellipticals and whether there is a connection
between the merger events we detect and the current nuclear activity.
We must therefore place our results into a larger statistical context.
We are currently conducting an HST archival study of inactive
elliptical galaxies {AR-10941} to form a control sample. We now
propose to obtain deep HST/WFPC2 images of 13 QSOs whose host galaxies
are classified as normal ellipticals. Comparing the results for both
samples will help us determine whether classical QSOs reside in normal
elliptical galaxies or not. Our recent pilot study of five QSOs
indicates that we can expect exciting results and deep insights into
the host galaxy morphology also for this larger sample of QSOs. A
statistically meaningful sample will help us determine the true
fraction of QSO hosts that suffered strong tidal interactions and
thus, whether a merger is indeed a requirement to trigger nuclear
activity in the most luminous AGNs. In addition to our primary science
observations with WFPC2, we will obtain NICMOS3 parallel observations
with the overall goal to select and characterize galaxy populations at
high redshifts. The imaging will be among the deepest NICMOS images:
These NICMOS images are expected to go to a limit a little over 1
magnitude brighter than HUDF-NICMOS data, but over 13 widely separated
fields, with a total area about 1.5 times larger than HUDF-NICMOS.
This separation means that the survey will tend to average out effects
of cosmic variance. The NICMOS3 images will have sufficient resolution
for an initial characterization of galaxy morphologies, which is
currently one of the most active and promising areas in approaching
the problem of the formation of the first massive galaxies. The depth
and area coverage of our proposed NICMOS observations will also allow
a careful study of the mass function of galaxies at these redshifts.
This provides a large and unbiased sample, selected in terms of
stellar mass and unaffected by cosmic variance, to study the on-going
star formation activity as a function of mass {i.e. integrated star
formation} at this very important epoch.

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 any time.

WFPC2 11029

WFPC2 CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly

Intflat observations will be taken to provide a linearity check: the
linearity test consists of a series of intflats in F555W, in each gain
and each shutter. A combination of intflats, visflats, and earthflats
will be used to check the repeatability of filter wheel motions.
{Intflat sequences tied to decons, visits 1-18 in prop 10363, have
been moved to the cycle 15 decon proposal xxxx for easier scheduling.}
Note: long-exposure WFPC2 intflats must be scheduled during ACS
anneals to prevent stray light from the WFPC2 lamps from contaminating
long ACS external exposures.

WFPC2 11028

WFPC2 Cycle 15 UV Earth Flats

Monitor flat field stability. This proposal obtains sequences of earth
streak flats to improve the quality of pipeline flat fields for the
WFPC2 UV filter set. These Earth flats will complement the UV earth
flat data obtained during cycles 8-14.

NIC1 10889

The Nature of the Halos and Thick Disks of Spiral Galaxies

We propose to resolve the extra-planar stellar populations of the
thick disks and halos of seven nearby, massive, edge-on galaxies using
ACS, NICMOS, and WFPC2 in parallel. These observations will provide
accurate star counts and color-magnitude diagrams 1.5 magnitudes below
the tip of the Red Giant Branch sampled along the two principal axes
and one intermediate axis of each galaxy. We will measure the
metallicity distribution functions and stellar density profiles from
star counts down to very low average surface brightnesses, equivalent
to ~32 V-mag per square arcsec. These observations will provide the
definitive HST study of extra-planar stellar populations of spiral
galaxies. Our targets cover a range in galaxy mass, luminosity, and
morphology and as function of these galaxy properties we will provide:
- The first systematic study of the radial and isophotal shapes of the
diffuse stellar halos of spiral galaxies - The most detailed
comparative study to date of thick disk morphologies and stellar
populations - A comprehensive analysis of halo and thick disk
metallicity distributions as a function of galaxy type and position
within the galaxy. - A sensitive search for tidal streams - The first
opportunity to directly relate globular cluster systems to their field
stellar population We will use these fossil records of the galaxy
assembly process preserved in the old stellar populations to test halo
and thick disk formation models within the hierarchical galaxy
formation scheme. We will test LambdaCDM predictions on sub-galactic
scales, where it is difficult to test using CMB and galaxy redshift
surveys, and where it faces its most serious difficulties.


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


11131 - REACQ(1,2,2) fine lock backup on FGS 1

REACQ(1,2,2) at 004/22:11:51 acquired in fine lock backup on FGS 1
only, with QF2STOPF and QSTOP flags set on FGS 2. No other flags were
seen. Initial GSACQ(1,2,2) at 19:01:32 and REACQ at 20:35:56 were

11132 - GSAcq(2,3,3) results in fine lock backup (2,0,2) using FGS-2

Upon acquisition of signal at 006/01:04:35, the GSAcq(2,3,3) scheduled
at 006/00:00:08-00:08:13 had resulted to fine lock backup (2,0,2)
using FGS-2, due to stop flag (QF3STOPF) indication on FGS-3.
Pre-acquisition OBADs attitude error correction (RSS) values, and
post-acq OBAD/MAP (RSS) value are not available pending future ETR

11133 - GSAcq(2,1,2) Loss of Lock while guiding

Following successful GSAcq(2,1,2) scheduled at 006/01:24:12 a Loss of
Lock occurred while guiding with FGS 1 and FGS 2 at 006/02:12:31. The
mnemonic QDVFGSM0 (FGS Attitude Error Angle) broke limit at
006/02:12:46 with a Red High value of 0.000939489 radians. The
spacecraft entered M2G Mode at 006/02:12:38. The TERM EXP was not
scheduled until 006/02:22:47.



*********************** SCHEDULED***** SUCCESSFUL***** FAILURE TIMES

FGS GSacq************** 24****************** 24
FGS REacq************** 17****************** 17
OBAD with Maneuver **** 86****************** 86
LOSS of LOCK********************************************** *****



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