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 # 4393
PERIOD COVERED: UT June 27, 2007 (DOY 178)
OBSERVATIONS SCHEDULED
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.
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.
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.
WFPC2 10818
Very Young Globular Clusters in M31 ?
We propose to use HST's unique high spatial resolution
imaging
capabilities to conclusively confirm or refute the
presence of alleged
very young globular clusters in M31. Such young globular
clusters with
ages < 3 Gyr are not present in our galaxy, and, if
real, would lead to
a striking difference in the age distribution of the GCs
between M31 and
the
in M31 is confirmed through our proposed ACS imaging {now
WFPC2 imaging}
with HST, this would suggest major differences in the
history of
assembly of the two galaxies, with probable substantial
late accretion
into M31 which did not occur in our own galaxy.
WFPC2 11140
Can mass-ejections from late He-shell flash stars
constrain
convective/reactive flow modeling of stellar interiors?
The existence of H-deficient knots around the central
stars of the
planetary nebulae Abell 30 and Abell 78 is still
unexplained. We
hypothesize that these knots were ejected during a very
late
helium-shell flash {= very late thermal pulse, VLTP}
suffered by the
precursor white dwarf stars. If this is true, then the
characteristics
of these knots {mass, velocity, density, spatial
distribution} allow to
draw conclusions on the course of the hydrogen- ingestion
flash
detonation that is triggered by the He-shell flash. This
provides
important, otherwise inaccessible constraints for the
hydrodynamical
modeling of convective/reactive flows in stellar
interiors.
Understanding the physics of these flows is not only
important for the
understanding of these particular central stars, but also
for the
frequent, very similar convective/reactive events that
determine the
nucleosynthesis in Pop. III stars. With this proposal we
want to proof
or discard the idea that the H-deficient knots are
resulting from a
VLTP. If true, then they can be exploited for flash-physics
diagnostics.
We propose a simple test. We search for such knots around
five
H-deficient central stars {PG1159 stars}. Our models
predict, that only
those stars with residual nitrogen in the atmosphere have
suffered a
VLTP and, hence, should have expelled knots. We therefore
want to take
[O III] images of stars which have photospheric N and
those which do
not.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
7
7
FGS
REacq
5
5
OBAD with
Maneuver
26
26
COMPLETED OPS NOTES: (None)
SIGNIFICANT EVENTS:
Intercept SMS SA176R02 was received, reviewed and is
authorized. The intercept
time is 179/19:36:26z