HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4549
PERIOD
COVERED: UT February 15,16,17,18, 2008 (DOY 046,047,048,049)
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 i
mages.
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.
NIC3
11236
Did
Rare, Large Escape-Fraction Galaxies Reionize the Universe?
Lyman
continuum photons produced in massive starbursts may have played a
dominant
role in the reionization of the Universe. Starbursts are
important
contributors to the ionizing metagalactic background at lower
redshifts
as well. However, their contribution to the background depends
upon
the fraction of ionizing radiation that escapes from the intrinsic
opacity
of galaxies below the Lyman limit. Current surveys suggest that
the
escape fraction is close to zero in most galaxies, even among young
starbursts,
but is large in 15-25% of them. Non-uniform escape fractions
are
expected as a result of violent events creating clear paths in small
parts
of galaxies. The number of galaxies observed with high escape
fraction
will result from the combination of the intrinsic number with
clear
lines of sight and their orientation with respect to the observer.
We
propose to measure the fraction of escaping Lyman continuum radiation
in
a large sample (47) of z~0.7 starbursts in the COSMOS field. These
compact
UV-luminous galaxies are good analogs to high redshift LBGs.
Using
the SBC/PR130L we can quickly (1-4 orbits) detect relative escape
fractions
(f_LC/f_1500) of 25% or more. This will be the first
measurement
of the escape fraction in sources between z=1 and the local
universe.
We expect ~10 detections. Stacking will set limits of <4% on
the
relative escape fraction in the rest. We will correlate the LC
detections
with the properties of the galaxies. By targeting z~0.7 in
COSMOS,
we will have tremendous ancillary information on those sources.
A
non-detection in all sources would be significant (99% confidence).
This
would imply that QSOs provide the overwhelming majority of ionizing
radiation
at z<1, requiring substantial evolution in the processes within
Lyman
break galaxies which allow large escape fractions at high
redshift.
WFPC2
11229
SEEDS:
The Search for Evolution of Emission from Dust in Supernovae with
HST
and Spitzer
The
role that massive stars play in the dust content of the Universe is
extremely
uncertain. It has long been hypothesized that dust can
condense
within the ejecta of supernovae {SNe}, however there is a
frustrating
discrepancy between the amounts of dust found in the early
Universe,
or predicted by nucleation theory, and inferred from SN
observations.
Our SEEDS collaboration has been carefully revisiting the
observational
case for dust formation by core- collapse SNe, in order to
quantify
their role as dust contributors in the early Universe. As dust
condenses
in expanding SN ejecta, it will increase in optical depth,
producing
three simultaneously observable phenomena: {1} increasing
optical
extinction; {2} infrared {IR} excesses; and {3} asymmetric
blue-shifted
emission lines. Our SEEDS collaboration recently reported
all
three phenomena occurring in SN2003gd, demonstrating the success of
our
observing strategy, and permitting us to derive a dust mass of up to
0.02
solar masses created in the SN. To advance our understanding of the
origin
and evolution of the interstellar dust in galaxies, we propose to
use
HST's WFPC2 and NICMOS instruments plus Spitzer's photometric
instruments
to monitor ten recent core-collapse SNe for dust formation
and,
as a bonus, detect light echoes that can affect the dust mass
estimates.
These space-borne observations will be supplemented by
ground-based
spectroscopic monitoring of their optical emission line
profiles.
These observations would continue our 2-year HST and Spitzer
monitoring
of this phenomena in order to address two key questions: Do
all
SNe produce dust? and How much dust do they produce? As all the SN
are
within 15 Mpc, each SN stands an excellent chance of detection with
HST
and Spitzer and of resolving potential light echoes.
ACS/SBC
11225
The
Wavelength Dependence of Accretion Disk Structure
We
can now routinely measure the size of quasar accretion disks using
gravitational
microlensing of lensed quasars. The next step to testing
accretion
disk models is to measure the size of accretion disks as a
function
of wavelength, particularly at the UV and X-ray wavelengths
that
should probe the inner, strong gravity regime. Here we focus on two
four-image
quasar lenses that already have optical {R band} and X-ray
size
measurements using microlensing. We will combine the HST
observations
with ground-based monitoring to measure the disk size as a
function
of wavelength from the near-IR to the UV. We require HST to
measure
the image flux ratios in the ultraviolet continuum near the
Lyman
limit of the quasars. The selected targets have estimated black
hole
masses that differ by an order of magnitude, and we should find
wavelength
scalings for the two systems that are very different because
the
Blue/UV wavelengths should correspond to parts of the disk near the
inner
edge for the high mass system but not in the low mass system. The
results
will be modeled using a combination of simple thin disk models
and
complete relativistic disk models. While requiring only 18 orbits,
success
for one system requires observations in both Cycles 16 and 17.
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
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
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.
WEPC2
11196
An
Ultraviolet Survey 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 starbursts and creating/fueling central AGN. We
propose
far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV imaging of a
sample
of 27 galaxies drawn from the complete IRAS Revised Bright Galaxy
Sample
{RBGS} LIRGs sample and known, from our Cycle 14 B and I-band ACS
imaging
observations, to have significant numbers of bright {23 < B < 21
mag}
star clusters in the central 30 arcsec. The HST UV data will be
combined
with previously obtained HST, Spitzer, and GALEX images to {i}
calculate
the ages of the clusters as function of merger stage, {ii}
measure
the amount of UV light in massive star clusters relative to
diffuse
regions of star formation, {iii} assess the feasibility of using
the
UV slope to predict the far-IR luminosity {and thus the star
formation
rate} both among and within IR-luminous galaxies, and {iv}
provide
a much needed catalog of rest- frame UV morphologies for
comparison
with rest-frame UV images of high-z LIRGs and Lyman Break
Galaxies.
These observations will achieve the resolution required to
perform
both detailed photometry of compact structures and spatial
correlations
between UV and redder wavelengths for a physical
interpretation
our IRX-Beta results. The HST UV data, combined with the
HST
ACS, Spitzer, Chandra, and GALEX observations of this sample, will
result
in the most comprehensive study of luminous starburst galaxies to
date.
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
4.5<z<6.5,
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.
NIC3
11149
Characterizing
the Stellar Populations in Lyman-Alpha Emitters and Lyman
Break
Galaxies at 5.7<z<7 in the Subaru Deep Field
The
epoch of reionization marks a major phase transition of the
Universe,
during which the intergalactic space became transparent to UV
photons.
Determining when this occurred and the physical processes
involved
represents the latest frontier in observational cosmology. Over
the
last few years, searches have intensified to identify the population
of
high-redshift (z>6) galaxies that might be responsible for this
process,
but the progress is hampered partly by the difficulty of
obtaining
physical information (stellar mass, age, star formation
rate/history)
for individual sources. This is because the number of z>6
galaxies
that have both secure spectroscopic redshifts and high-quality
infrared
photometry (especially with Spitzer/IRAC) is still fairly
small.
Considering that only several photometric points are available
per
source, and that many model SEDs are highly degenerate, it is
crucial
to obtain as many observational constraints as possible for each
source
to ensure the validity of SED modeling. To better understand the
physical
properties of high-redshift galaxies, we propose here to
conduct
HST/NICMOS (72 orbits) and Spitzer/IRAC (102 hours) imaging of
spectroscopically
confirmed, bright (z<26 mag (AB)) Ly-alpha emitters
(LAEs)
and Lyman-break galaxies (LBGs) at 5.7<z<7 selected from the
Subaru
Deep Field. Spectroscopic redshifts remove one critical free
parameter
from SED modeling while bright source magnitudes ensure
high-quality
photometric data. By making accurate determinations of
stellar
masses, ages, and star-formation histories, we will specifically
address
the following major questions: (1) Do LAEs and LBGs represent
physically
different galaxy populations at z>6 as suggested recently?
(2)
Is Ly-alpha emission systematically suppressed at z>6 with respect
to
continuum emission? (i.e., are we reaching the epoch of incomplete
reionization?),
and (3) Do we see any sign of abnormally young stellar
population
in any of the z>6 galaxies?
NIC2
11148
High
Contrast Imaging of Dusty White Dwarfs
For
the past 18 years, only one white dwarf with a circumstellar dust
disk
was known to exist. In the last two years, six new disks have been
discovered.
Since all material inwards of a few AU should be scoured
clean
during post main sequence evolution, the primary explanation is
the
presence of a planetary system that is perturbing relic
planetesimals
into the tidal disruption radius of the white dwarf. Dusty
disks
around white dwarfs should be markers for planets and we propose
to
use high contrast imaging to search for faint companions down to 6
M_$J$
that may be feeding the disks. White dwarfs are uniquely suited
for
planet searches, where the planet/white dwarf contrast is less than
for
main sequence stars.
ACS/SBC
11145
Probing
the Planet Forming Region of T Tauri Stars in Chamaeleon
By
studying the inner, planet-forming regions of circumstellar disks
around
low-mass pre-main sequence stars we can refine theories of giant
planet
formation and develop timescales for the evolution of disks and
their
planets. Spitzer infrared observations of T Tauri stars in the
Chamaeleon
star-forming region have given us an unprecedented look at
dust
evolution in young objects. However, despite this ground breaking
progress
in studying the dust in young disks, the gas properties of the
inner
disk remain essentially unknown. Using ACS on HST, we propose to
measure
the H_2 emission originating in the innermost disk regions of
classical
T Tauri stars in different stages of evolution with the
objective
of revealing the timescales of gas dissipation and its
relationship
to dust evolution. This proposal is part of a comprehensive
effort
with approved programs on Spitzer, Gemini, and Magellan that aim
to
characterize the state of gas and dust in disks where planets may
already
have formed.
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
Galaxies
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 {
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 time.
WFPC2
11070
WFPC2
CYCLE 15 Standard Darks - part II
This
dark calibration program obtains dark frames every week in order to
provide
data for the ongoing calibration of the CCD dark current rate,
and
to monitor and characterize the evolution of hot pixels. Over an
extended
period these data will also provide a monitor of radiation
damage
to the CCDs.
WFPC2
11030
WFPC2
WF4 Temperature Reduction #3
In
the fall of 2005, a serious anomaly was found in images from the WF4
CCD
in WFPC2. The WF4 CCD bias level appeared to have become unstable,
resulting
in sporadic images with either low or zero bias level. The
severity
and frequency of the problem was rapidly increasing, making it
possible
that WF4 would soon become unusable if no work-around were
found.
Examination of bias levels during periods with frequent WFPC2
images
showed low and zero bias episodes every 4 to 6 hours. This
periodicity
is driven by cycling of the WFPC2 Replacement Heater, with
the
bias anomalies occurring at the temperature peaks. The other three
CCDs
{PC1, WF2, and WF3} appear to be unaffected and continue to operate
properly.
Lowering the Replacement Heater temperature set points by a
few
degrees C effectively eliminates the WF4 anomaly. On 9 January 2006,
the
upper set point of the WFPC2 Replacement Heater was reduced from
14.9C
to 12.2C. On 20 February 2006, the upper set point was reduced
from
12.2C to 11.3C, and the lower set point was reduced from 10.9C to
10.0C.
These changes restored the WF4 CCD bias level; however, the bias
level
has begun to trend downwards again, mimicking its behavior in late
2004
and early 2005. A third temperature reduction is planned for March
2007.
We will reduce the upper set point of the heater from 11.3C to
10.4C
and the lower set point from 10.0C to 9.1C. The observations
described
in this proposal will test the performance of WFPC2 before and
after
this temperature reduction. Additional temperature reductions may
be
needed in the future, depending on the performance of WF4. Orbits:
internal
26, external 1
WFPC2
11024
WFPC2
CYCLE 15 INTERNAL MONITOR
This
calibration proposal is the Cycle 15 routine internal monitor for
WFPC2,
to be run weekly to monitor the health of the cameras. A variety
of internal
exposures are obtained in order to provide a monitor of the
integrity
of the CCD camera electronics in both bays {both gain 7 and
gain
15 -- to test stability of gains and bias levels}, a test for
quantum
efficiency in the CCDs, and a monitor for possible buildup of
contaminants
on the CCD windows. These also provide raw data for
generating
annual super-bias reference files for the calibration
pipeline.
ACS/SBC
10862
Comprehensive
Auroral Imaging of Jupiter and Saturn during the
International
Heliophysical Year
A
comprehensive set of observations of the auroral emissions from
Jupiter
and Saturn is proposed for the International Heliophysical Year
in
2007, a unique period of especially concentrated measurements of
space
physics phenomena throughout the solar system. We propose to
determine
the physical relationship of the various auroral processes at
Jupiter
and Saturn with conditions in the solar wind at each planet.
This
can be accomplished with campaigns of observations, with a sampling
interval
not to exceed one day, covering at least one solar rotation.
The
solar wind plasma density approaching Jupiter will be measured by
the
New Horizons spacecraft, and a separate campaign near opposition in
May
2007 will determine the effect of large-scale variations in the
interplanetary
magnetic field {IMF} on the Jovian aurora by
extrapolation
from near-Earth solar wind measurements. A similar Saturn
campaign
near opposition in Jan. 2007 will combine extrapolated solar
wind
data with measurements from a wide range of locations within the
Saturn
magnetosphere by Cassini. In the course of making these
observations,
it will be possible to fully map the auroral footprints of
Io
and the other satellites to determine both the local magnetic field
geometry
and the controlling factors in the electromagnetic interaction
of
each satellite with the corotating magnetic field and plasma density.
Also
in the course of making these observations, the auroral emission
properties
will be compared with the properties of the near-IR
ionospheric
emissions {from ground-based observations} and non thermal
radio
emissions, from ground-based observations for Jupiter's decametric
radiation
and Cassini plasma wave measurements of the Saturn Kilometric
Radiation
{SKR}.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
11193
- GSAcq(1,2,2) failed to RGA Hold (Gyro Control)
Upon acquisition of signal at 046/21:51:53, the GSAcq(1,2,2)
scheduled
at 046/21:13:21- 21:21:26 had failed to RGA Hold due to (QF1STOPF)
stop
flag indication on FGS-1. Pre-acq OBADs attitude correction data
unavailable pending future Engineering Tape Recorder dump.
Post-acq
OBAD/MAP had (RSS) value of 12.03 arcseconds. Received multiple
ACS 779
Status Buffer Messages ("Fold Mechanism Move was
Blocked") following the
failure of the GSAcq.
11194
- GSAcq (2,1,1) failed due to Search Radius Limit Exceeded on FGS 2
At 048/18:04:22, GSAcq (2,1,1) scheduled from 17:59:43-18:07:05
failed
due to Search Radius Limit Exceeded on FGS 2. Received one 486 ESB
message "a05", Exceeded SRL. OBAD #1 RSS = 963.23 a-s.
OBAD #2 RSS =
42.16 a-s. OBAD MAP RSS = 46.97 a-s. Additionally, received 5 ACS
779
Status Buffer Messages ("Fold Mechanism Move was
Blocked") following the
failure of the GSacq. This resulted in the TDF to be down when the
Fold
mechanism move was commanded. Flight Software Error Count
(JERRCNT)
incremented to 75. OPS Note 1645-12 was executed to change JERRCNT
limit
to 75.
REAcq (2,1,1) scheduled at 19:33:50 was successful.
11196
- GSAcq(1,2,2) required two attempts for ct-dv
GSAcq(1,2,2) at 035/00:50:59 required two attempts to achieve
ct-dv on
FGS1. The acquisition was successful.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
34
32
FGS
REacq
25
25
OBAD
with Maneuver
113
113
SIGNIFICANT
EVENTS: (None)