Notice: For the foreseeable future, the daily reports may
contain
apparent discrepancies between some proposal descriptions
and the listed
instrument usage. This is due to the conversion of
previously approved
ACS WFC or HRC observations into WFPC2, or NICMOS
observations
subsequent to the loss of ACS CCD science capability in
late January.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4390
PERIOD COVERED: UT June 22,23,24, 2007 (DOY 173,174,175)
OBSERVATIONS SCHEDULED
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 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.
NIC2 11157
NICMOS Imaging Survey of Dusty Debris Around Nearby Stars
Across the
Stellar Mass Spectrum
Association of planetary systems with dusty debris disks
is now quite
secure, and advances in our understanding of planet
formation and
evolution can be achieved by the identification and
characterization of
an ensemble of debris disks orbiting a range of central
stars with
different masses and ages. Imaging debris disks in
starlight scattered
by dust grains remains technically challenging so that
only about a
dozen systems have thus far been imaged. A further advance
in this field
needs an increased number of imaged debris disks. However,
the technical
challege of such observations, even with the superb
combination of HST
and NICMOS, requires the best targets. Recent HST imaging
investigations
of debris disks were sample-limited not limited by the
technology used.
We performed a search for debris disks from a
IRAS/Hipparcos cross
correlation which involved an exhaustive background
contamination check
to weed out false excess stars. Out of ~140 identified
debris disks, we
selected 22 best targets in terms of dust optical depth
and disk angular
size. Our target sample represents the best currently
available target
set in terms of both disk brightness and resolvability.
For example, our
targets have higher dust optical depth, in general, than
newly
identified Spitzer disks. Also, our targets cover a wider
range of
central star ages and masses than previous debris disk
surveys. This
will help us to investigate planetary system formation and
evolution
across the stellar mass spectrum. The technical
feasibility of this
program in two-gyro mode guiding has been proven with on-
orbit
calibration and science observations during HST cycles 13,
14, and 15.
WFPC2 11079
Treasury Imaging of Star Forming Regions in the Local
Group:
Complementing the GALEX and NOAO Surveys
We propose to use WFPC2 to image the most interesting
star-forming
regions in the Local Group galaxies, to resolve their
young stellar
populations. We will use a set of filters including F170W,
which is
critical to detect and characterize the most massive
stars, to whose hot
temperatures colors at longer wavelengths are not
sensitive. WFPC2's
field of view ideally matches the typical size of the
star-forming
regions, and its spatial resolution allows us to measure
indvidual
stars, given the proximity of these galaxies. The
resulting H- R
diagrams will enable studies of star-formation properties
in these
regions, which cover largely differing metallicities {a
factor of 17,
compared to the factor of 4 explored so far} and
characteristics. The
results will further our understanding of the
star-formation process, of
the interplay between massive stars and environment, the
properties of
dust, and will provide the key to interpret integrated
measurements of
star-formation indicators {UV, IR, Halpha} available for
several
hundreds more distant galaxies. Our recent deep surveys of
these
galaxies with GALEX {FUV, NUV} and ground-based imaging
{UBVRI, Halpha,
[OIII] and [SII]} provided the identification of the most
relevant SF
sites. In addition to our scientific analysis, we will
provide catalogs
of HST photometry in 6 bands, matched corollary
ground-based data, and
UV, Halpha and IR integrated measurements of the
associations, for
comparison of integrated star-formation indices to the
resolved
populations. We envisage an EPO component.
WFPC2 11040
Geometric Distortion / Astrometry Closeout
These observations will serve as a final characterization
of the
geometric distortion and astrometric calibration. The
Omega-Cen inner
calibration field is used. Filters F300W, F555W, and F814W
are observed
at 5 roll angles spanning 180 degrees; F218W is observed
at a single
roll angle.
FGS 11019
Monitoring FGS1r's Interferometric Response as a Function
of Spectral
Color
This proosal uses FGS1r in Transfer mode to observe
standard single
stars of a variety of spectral types to obtain point
source
interferograms for the Transfer mode calibration library.
In specific
cases, the calibration star will also be observed in POS
mode multiple
times with the F583W and F5ND elements to provide the data
to verify the
stabiligy of the cross filter calibration.
WFPC2 10922
Searching for Signs of a Double Generation of Stars in
Galactic Globular
Clusters
This proposal has been stimulated by new findings of ours
that may have
a strong impact on the interpretation of globular cluster
{GC} stellar
populations. In 2004, based on HST data, we have found
that the main
sequence of the Galactic globular cluster Omega Centauri
is split into
two sequences; spectroscopic analysis has shown that the
only isochrones
which are able to fit the combination of color and
metallicity of the
bluest of the two sequences were younger and greatly
enriched in helium.
A number of observational facts, and theoretical evidence
suggest that
our results on Omega Centauri might represent an extreme
case of a
phenomenon which has also been at work in other GCs. We
have selected
the most promising GCs to find out whether this hypothesis
is correct,
and make a strong case for its likelihood and the value of
pursuing it.
NIC2 10893
Sweeping Away the Dust: Reliable Dark Energy with an
Infrared Hubble
Diagram
We propose building a high-z Hubble Diagram using type Ia
supernovae
observed in the infrared rest-frame J-band. The infrared
has a number of
exceptional properties. The effect of dust extinction is
minimal,
reducing a major systematic tha may be biasing dark energy
measurements.
Also, recent work indicates that type Ia supernovae are
true standard
candles in the infrared meaning that our Hubble diagram
will be
resistant to possible evolution in the Phillips relation
over cosmic
time. High signal-to-noise measurements of 9 type Ia
events at z~0.4
will be compared with an independent optical Hubble
diagram from the
ESSENCE project to test for a shift in the derived dark
energy equation
of state due to a systematic bias. Because of the bright
sky background,
H-band photometry of z~0.4 supernovae is not feasible from
the ground.
Only the superb image quality and dark infrared sky seen
by HST makes
this test possible. This experiment may also lead to a
better, more
reliable way of mapping the expansion history of the
universe with the
Joint Dark Energy Mission.
WFPC2 10890
Morphologies of the Most Extreme High-Redshift
Mid-IR-Luminous Galaxies
The formative phase 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,
restricting us to the study of 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 bright at mid-IR wavelengths
{F[24um]>0.8mJy}, but deep ground based imaging
suggests extremely faint
{and in some cases extended} optical counterparts
{R~24-27}. Deep K-band
images show barely resolved galaxies. Mid-infrared
spectroscopy with
Spitzer/IRS reveals that they have redshifts z ~ 2-2.5,
suggesting
bolometric luminosities ~10^{13-14}Lsun! We propose to
obtain deep ACS
F814W and NIC2 F160W images of these sources and their
environs in order
to determine kpc-scale morphologies and surface photometry
for these
galaxies. The proposed observations will help us determine
whether these
extreme 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 10877
A Snapshot Survey of the Sites of Recent, Nearby
Supernovae
During the past few years, robotic {or nearly robotic}
searches for
supernovae {SNe}, most notably our Lick Observatory
Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite
nearby
galaxies {cz < 4000 km/s}. Most of the objects were
discovered before
maximum brightness, and have follow-up photometry and
spectroscopy; they
include some of the best-studied SNe to date. We propose
to conduct a
snapshot imaging survey of the sites of some of these
nearby objects, to
obtain late-time photometry that {through the shape of the
light and
color curves} will help reveal the origin of their
lingering energy. The
images will also provide high-resolution information on
the local
environments of SNe that are far superior to what we can
procure from
the ground. For example, we will obtain color-color and
color-magnitude
diagrams of stars in these SN sites, to determine the SN
progenitor
masses and constraints on the reddening. Recovery of the
SNe in the new
HST images will also allow us to actually pinpoint their
progenitor
stars in cases where pre- explosion images exist in the
HST archive.
This proposal is an extension of our successful Cycle 13
snapshot survey
with ACS. It is complementary to our Cycle 15 archival
proposal, which
is a continuation of our long-standing program to use
existing HST
images to glean information about SN environments.
ACS/SBC 10872
Lyman Continuum Emission in Galaxies at z=1.2
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
escape fractions of a few percent, up to 10%, with very
few detections
{as opposed to upper limits} having been reported. No
detections have
been reported in the epochs between z=0.1 and z=2. We propose
to measure
the fraction of escaping Lyman continuum radiation from 15
luminous
z~1.2 galaxies in the GOODS fields. Using the tremendous
sensitivity of
the ACS Solar- blind Channel, we will reach AB=30 mag.,
allowing us to
detect an escape fraction of 1%. We will correlate the
amount of
escaping radiation with the photometric and morphological
properties of
the galaxies. A non-detection in all sources would imply
that QSOs
provide the overwhelming majority of ionizing radiation at
z=1.3, and it
would strongly indicate that the properties of galaxies at
higher
redshift have to be significantly different for galaxies
to dominate
reionization. The deep FUV images will also be useful for
extending the
FUV study of other galaxies in the GOODS fields.
NIC2 10849
Imaging Scattered Light from Debris Disks Discovered by
the Spitzer
Space Telescope around 21 Sun-like Stars
We propose to use the high-contrast capability of the
NICMOS coronagraph
to image a sample of newly discovered circumstellar disks
associated
with Sun-like stars. These systems were identified by
their strong
thermal infrared {IR} emission with the Spitzer Space
Telescope as part
of the Spitzer Legacy Science program titled "The
Formation and
Evolution of Planetary Systems" {FEPS, P.I.:
M.Meyer}. Modeling of the
thermal excess emission from the spectral energy
distributions alone
cannot distinguish between narrowly confined high-opacity
disks and
broadly distributed, low-opacity disks. By resolving light
scattered by
the circumstellar material, our proposed NICMOS
observations can break
this degeneracy, thus revealing the conditions under which
planet
formation processes are occuring or have occured. For
three of our
IR-excess stars that have known radial-velocity planets,
resolved
imaging of the circumstellar debris disks may further
offer an
unprecedented view of planet-disk interactions in an
extrasolar
planetary system. Even non-detections of the light
scattered by the
circumstellar material will place strong constraints on
the disk
geometries, ruling out disk models with high optical
depth. Unlike
previous disk imaging programs, our program contains a
well-defined
sample of ~1 solar mass stars covering a range of ages
from 3 Myr to 3
Gyr, thus allowing us to study the evolution of disks from
primordial to
debris for the first time. The results from our program
will greatly
improve our understanding of the architecture of debris
disks around
Sun-like stars, and will create a morphological context
for the
existence of our own solar system. This proposal is for a
continuation
of an approved Cycle 14 program {GO/10527, P.I.: D.
Hines}.
WFPC2 10834
The Shell of the Recurrent Nova T Pyx
T Pyx is the only known recurrent nova with a shell. This
'shell' is
mysterious because it has been resolved into thousands of
knots that
apparently aren't expanding. We propose to take a deep
F658N image of T
Pyx during one orbit to serve as a 12 year baseline from
the previous
HST WFPC2 images in 1994 and 1995. This much longer
baseline will allow
us to push down the limits on expansion velocities to ~10
km/s and will
allow us to measure the lifetimes of the knots. Also, we
expect to
discover the expanding inner shell from the last eruption
in 1966 which
should now have expanded to ~0.9" in radius. Detailed
modeling of the
observed line fluxes will give the mass of the individual
knots and the
shells. The details of the expansion velocities,
lifetimes, and masses
of the knots will determine the nature of the T Pyx shell;
with
alternatives being a nova shell, a planetary nebula,
stalled shocks in a
pre-existing shell, or a cloud ionized by the high
luminosity and
temperature of the white dwarf. If we can separate out the
mass ejected
during the 1966 eruption, then we can compare it to the
total mass
accreted between the 1944 and 1966 eruptions {6.0x10^-6
solar mass} so
as to determine whether the white dwarf is gaining or
losing mass on
average. If the white dwarf is gaining mass, then it must
inevitably
exceed the Chandrasekhar mass and collapse as a Type Ia
supernova, and
thus recurrent novae would be shown to be an important
component of the
solution to the Type Ia progenitor problem.
ACS/SBC 10810
The Gas Dissipation Timescale: Constraining Models of
Planet Formation
We propose to constrain planet-formation models by
searching for
molecular hydrogen emission around young {10-50 Myr}
solar-type stars
that have evidence for evolved dust disks. Planet
formation models show
that the presence of gas in disks is crucial to the
formation of BOTH
giant and terrestrial planets, influences dust dynamics,
and through
tidal interactions with giant planets leads to orbital
migration.
However, there is a lack of systematic information on the
presence and
lifetime of gas residing at planet-forming radii. We will
use a newly
identified broad continuum emission feature of molecular
hydrogen at
1600 Angstrom to search for residual gas within an orbital
radius of
5-10 AU around young stars that have evolved beyond the
optically thick
T Tauri phase. These observations will enable the most
sensitive probe
to date of remant gas in circumstellar disks, detecting
surfaces
densites of ~0.0001 g/cm^2, or less than 10^-5 of the
theoretical
"mininum mass" solar nebula from which our solar
system is thought to
have formed. Our observations are designed to be
synergistic with
ongoing searches for gas emission that is being performed
using the
Spitzer Space Telescope in that the proposed HST
observations are ~100
times more sensitive and will have 50 times higher angular
resolution.
These combined studies will provide the most comprehensive
view of
residual gas in proto-planetary disks and can set
important constraints
on models of planet formation.
WFPC2 10807
The knotty jet of He 2-90: An ideal laboratory for
studying the
formation and propagation of jets in dying stars
Previous WFPC2 observations have led to the serendipitous
discovery of
an extended, highly-collimated, ``pulsed" bipolar jet
emanating from a
compact planetary nebula, He 2- 90. Subsequently, an
average proper
motion of the knots in the jet was measured, which
together with radial
velocities, enabled us to characterise the basic physical
properties of
the jet. The knotty jet in He 2-90 resembles other
prominent examples of
pulsed jets in young stellar objects or symbiotic stars,
but is probably
by far the best example yet of a non-relativistic,
symmetric, jet in a
``clean" astrophysical environment. The formation
{acceleration and
collimation} of jets is not fully understood, specially in
the case of
jets in dying stars. We now propose to re-image He 2-90
with WFPC2 and
exploit the factor 3.5 longer time baseline now available
from the
first-epoch observations in September 1999, in order to
measure the
proper motion of individual knots in the jet with
unprecedented
accuracy. These data will enable us to characterise the
ejection history
of the source, specially deviations from a constant period
{latter is
related to the binary period of the system}, e.g., due to
instabilities
in the accretion mechanism. We will also be able to test
if the ejection
mechanism is symmetric: any deviation in the ejection
history of the
knots in the opposing jet beams, will indicate a magnetic
field
structure and/or the accretion disk which is not symmetric
across the
equatorial plane. We will also carry out deep imaging with
the ACS/WFC
camera in order to determine the shapes/sizes of a large
number of
knots. The shapes/sizes of the knots, and changes with
distance from the
source probe the strength of the magnetic field inside the
jet. HRC
imaging of the central source and jet on sub-arcsecond
scales will be
carried out to probe the magnetic field close to the jet
source, and
deviations from linearity in the jet-beam which may result
from
instabilities in the magnetic field. These data will allow
us to
significantly improve our existing 2- dimensional MHD
model of the
He2-90 jet, and/or provide impetus for new 3-dimensional
models.
WFPC2 10800
Kuiper Belt Binaries: Probes of Early Solar System
Evolution
Binaries in the Kuiper Belt are a scientific windfall: in
them we have
relatively fragile test particles which can be used as
tracers of the
early dynamical evolution of the outer Solar System. We
propose to
continue a Snapshot program using the ACS/HRC that has a
demonstrated
discovery potential an order of magnitude higher than the
HST
observations that have already discovered the majority of
known
transneptunian binaries. With this continuation we seek to
reach the
original goals of this project: to accumulate a
sufficiently large
sample in each of the distinct populations collected in
the Kuiper Belt
to be able to measure, with statistical significance, how
the fraction
of binaries varies as a function of their particular
dynamical paths
into the Kuiper Belt. Today's Kuiper Belt bears the
imprints of the
final stages of giant-planet building and migration;
binaries may offer
some of the best preserved evidence of that long-ago era.
NIC3 10504
Characterizing the Sources Responsible for Cosmic
Reionization
Our group has demonstrated the role that massive clusters,
acting as
powerful cosmic lenses, can play in constraining the
abundance and
properties of low-luminosity star- forming sources beyond
z~6; such
sources are thought to be responsible for ending cosmic
reionization.
The large magnification possible in the critical regions
of well-
constrained clusters brings sources into view that lie at
or beyond the
limits of conventional exposures such as the UDF, as well
as those in
imaging surveys being undertaken with IRAC onboard
Spitzer. We have
shown that the combination of HST and Spitzer is
particularly effective
in delivering the physical properties of these distant
sources,
constraining their mass, age and past star formation history.
Indirectly, we therefore gain a valuable glimpse to yet
earlier epochs.
Recognizing the result {and limitations} of the UDF
exposure, we propose
a systematic search through 6 lensing clusters with ACS
and NICMOS for
further z~6-7 sources in conjunction with existing deep
IRAC data. Our
survey will mitigate cosmic variance and extend the search
both to lower
luminosities and, by virtue of the NICMOS/IRAC
combination, to higher
redshift. The goal is to count and characterize
representative sources
at z~6-10 and to delineate the redshift range of activity
for the
planning of future observations.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be investigated.)
HSTARS:
10868 - GSAcq(1,2,1) failed to RGA Hold (Gyro Control)
Upon acquisition of signal at 174/06:56:20, the GSAcq(1,2,1) scheduled
at
174/05:39:58 - 05:48:03 had failed to RGA Hold due to (QF1STOPF) stop
flag indication on FGS-1. Pre-acquisition OBADs (RSS) attitude
correction values not available. Post-acq OBAD/MAP had (RSS) value of
812.49 arcseconds.
10869 - GSAcq(1,2,1) failed to RGA Hold (Gyro Control)
Upon acquisition of signal (AOS) at 175/06:06:35, the GSAcq(1,2,1)
scheduled at 175/05:38:12 - 05:46:17 had failed to RGA Hold due to
(QF1STOPF) stop flag indication on FGS-1. Pre-acquisition OBAD1 attitude
correction value not available due to LOS. OBAD2 had (RSS) value of 8.95
arcseconds. Post-acq OBAD/MAP had (RSS) value of 929.22 arcseconds.
COMPLETED OPS REQUEST:
18110-0 - Configure Kalman Filter for MSS/CSS/Gyro2
monitoring
SCHEDULED
SUCCESSFUL
FGS GSacq
19
17
FGS REacq
18
18
OBAD with Maneuver
74
74
COMPLETED OPS NOTES: (None)
SIGNIFICANT EVENTS:
Flash Report: Background Kalman Filter Operation.
The Kalman Filter was reconfigured to an MSS/CSS/Gyro2
configuration at
173/18:22 in support of a long-term KF monitoring test. It
will remain
in this configuration for approximately a week.