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 # 4392
PERIOD COVERED: UT June 26, 2007 (DOY 177)
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.
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.
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 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.
WFPC2 11112
The Collisional Ring Galaxy
NGC922
We request WFPC2 images of the newly recognized collisional ring galaxy
NGC922 which will become the
nearest such system observed by HST. These
will be used to get a clear
understanding of the geometry of the
interaction and the induced star formation
in this system. Quantitive
modeling of the colors of the star
clusters and stellar populations will
be used to constrain the star
formation history of the system. They will
also be used to test the
"infant mortality" scenario for star cluster
evolution. The derived population ages
will test predictions of how star
formation evolves in the various components
{ring, core, spokes} of
collisional rings, and will improve our own
simulations of this system.
These will be used to determine the final fate of the
stars formed in
the present burst - some will end
up in a central bar or bulge while
others will become part of a thickened
disk. By analogy this will tell
us how similar collisions enrich
stellar populations in the early
universe. This is especially relevant
since the number density of
collisional rings increases rapidly with redshift.
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:
10871 - OBAD Failed Identification
OBAD2
scheduled at 177/09:42:35 failed. Status Buffer message 1902 "OBAD
Failed Identification" was received. GSacq was
successful. OBAD1 RSS
error was 10957.43 arcseconds
COMPLETED OPS REQUEST:
18111-0 - Modify Magnitude Threshold Values in SOB Macros
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
04
04
FGS REacq
09
09
OBAD with Maneuver 24
23
SIGNIFICANT EVENTS:
Flash Report: FHST Stuck-on-Bottom (SOB) Macro
Visual-Magnitude
Threshold Modification:
Operations Request 18111-0 to modify the magnitude
threshold values in
the SOB macros to a magnitude value
of 3 was completed at 177/14:39:24.
-Lynn
____________________________________________________________
Lynn F. Bassford
Hubble Space Telescope
CHAMP Mission Operations
Manager
Lockheed Martin Mission Services (LMMS)
NASA GSFC PH#: 301-286-2876
"The Hubble Space Telescope is the
astronomical observatory and key to unlocking the most cosmic mysteries of the
past, present and future." - 7/26/6