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Daily Report #4393

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Old June 28th 07, 05:31 PM posted to sci.astro.hubble
Pataro, Pete
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Posts: 33
Default Daily Report #4393

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


PERIOD COVERED: UT June 27, 2007 (DOY 178)


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 Millky Way. If the
apparent presence of very young globular clusters 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.


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

HSTARS: (None)



FGS GSacq 7 7
FGS REacq 5 5
OBAD with Maneuver 26 26



Intercept SMS SA176R02 was received, reviewed and is authorized. The
intercept time is 179/19:36:26z

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