Daily Report #4158
- From: Lynn Bassford <lbassford@xxxxxxxxxxxx>
- Date: Wed, 19 Jul 2006 14:52:12 +0000 (UTC)
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 4158
PERIOD COVERED: UT July 18, 2006 (DOY 199)
OBSERVATIONS SCHEDULED
ACS/HRC 10598
ACS Imaging of Fomalhaut: A Rosetta Stone for Debris Disks Sculpted by
Planets
The Sun and roughly 15% of stars are surrounded by dust disks
collisionally replenished by asteroids and comets. Disk structure can
be directly tied to the dynamical influence of more massive bodies
such as planets. For example, planetary perturbations offset the
center of our zodiacal dust disk ~0.01 AU away from the Sun and also
maintain a ~40 AU radius inner edge to our Kuiper Belt. Here we
propose follow-up observation to the first optical detection of
reflected light from dust grains surrounding the nearby star Fomalhaut
using HST/ACS. We find a belt of material between 133 and 158 AU
radius that has a center position offset ~15 AU from the stellar
position, and with a sharp inner edge. A tenuous dust component
interior to the belt is also detected in the southeast. Given
Fomalhaut's proximity to the Sun {7.7 pc}, these images represent the
closest and highest angular resolution view of an extrasolar analog to
our Kuiper Belt. The center of symmetry offset and the sharp inner
edge of Fomalhaut's belt are evidence for planet-mass objects orbiting
the star as predicted by dynamical theory and simulations. We propose
comprehensive follow-up ACS imaging to fully exploit this discovery
and map the disk around its entire circumference with higher
signal-to-noise and at multiple wavelengths. HST/ACS is certainly the
only facility capable of performing this relatively wide field optical
study at high contrast ratios and diffraction-limited resolution. The
Cycle 14 data will provide key measurements of belt width as a
function of azimuth, the scattered light color of the belt versus the
inner dust component, and the azimuthal structure of the belt. These
data will be used to constrain dynamical models of resonances and
shepherding that ultimately elucidate the dynamical properties of
planet-mass objects in the system.
ACS/HRC 10738
Earth Flats
Sky flats will be obtained by observing the bright Earth with the HRC
and WFC. These observations will be used to verify the accuracy of the
flats currently in the pipeline and to monitor any changes. Weekly
coronagraphic monitoring is required to assess the changing position
of the spots.
ACS/HRC/WFC 10737
CCD Stability Monitor
This program will verify that the low frequency flat fielding, the
photometry, and the geometric distortion are stable in time and across
the field of view of the CCD detectors. A moderately crowded stellar
field in the cluster 47 Tuc is observed every three months with the
HRC {at the cluster core} and WFC {6' West of the cluster core} using
the full suite of broad and narrow band imaging filters. The positions
and magnitudes of objects will be used to monitor local and large
scale variations in the plate scale and the sensitivity of the
detectors and to derive an independent measure of the detector CTE. An
additional orbit is required to compare WFC observations taken at gain
1 with those taken at the new default gain 2.
ACS/WFC 10551
Gamma-Ray Bursts from Start to Finish: A Legacy Approach
The progenitors of long-duration GRBs are now known to be massive
stars. This result lends credence to the collapsar model, where a
rotating massive star ends its life leaving a black hole or a highly
magnetized neutron star, and confirms its essential aspects. The focus
of attention now is on the black hole or magnetar engines that power
the bursts. Somehow these engines create the most highly relativistic
and highly collimated outflows that we know of, through mechanisms
that no current theory can explain. These astrophysical laboratories
challenge our understanding of relativistic shocks, of mechanisms for
extracting energy from a black hole, and of how physics works in
extreme conditions. The launch of Swift is bringing us into a new era,
where we can make broadband observations that will enable us to study
these fascinating physical processes. We propose here an ambitious,
comprehensive program to obtain the datasets that will become the
standard that any successful model for the central engine must
explain. This programs leverages the HST observations to the maximum
extent by our commitment of Swift observations, a Large program at the
VLA, and extensive ground-based optical resources. By studying the
engines and searching for jets in a variety of events, this program
will investigate the conditions necessary for the engine and jet
formation itself.
ACS/WFC 10629
Are Field OB Stars Alone?
This SNAP program offers an inexpensive, simple program to search for
low-mass companions of field OB stars. Do field OB stars exist in true
isolation, as suggested by a recent Galactic study, or are they the
tip of the iceberg on a small cluster of low-mass stars as predicted
by the cluster mass function and stellar IMF? Short ACS/WFC V and I
observations proposed here may easily resolve this issue for field OB
stars in the Small Magellanic Cloud. Truly isolated OB stars represent
a theoretical challenge and variation from clusters, in mode of star
formation, and have important consequences for our understanding of
the field stellar population in galaxies. Small clusters around the
field OB stars, on the other hand, may confirm the universality of the
stellar clustering law and IMF.
ACS/WFC/NIC2 10496
Decelerating and Dustfree: Efficient Dark Energy Studies with
Supernovae and Clusters
We propose a novel HST approach to obtain a dramatically more useful
"dust free" Type Ia supernovae {SNe Ia} dataset than available with
the previous GOODS searches. Moreover, this approach provides a
strikingly more efficient search-and-follow-up that is primarily
pre-scheduled. The resulting dark energy measurements do not share the
major systematic uncertainty at these redshifts, that of the
extinction correction with a prior. By targeting massive galaxy
clusters at z > 1 we obtain a five-times higher efficiency in
detection of Type Ia supernovae in ellipticals, providing a
well-understood host galaxy environment. These same deep cluster
images then also yield fundamental calibrations required for future
weak lensing and Sunyaev-Zel'dovich measurements of dark energy, as
well as an entire program of cluster studies. The data will make
possible a factor of two improvement on supernova constraints on dark
energy time variation, and much larger improvement in systematic
uncertainty. They will provide both a cluster dataset and a SN Ia
dataset that will be a longstanding scientific resource.
CAL/ACS 10735
SBC MAMA Recovery
This proposal is designed for the initial turn-on of the ACS MAMA
detector and to permit recovery after an anomalous shutdown. Anomalous
shutdowns can occur as a result of bright object violations which
trigger the Bright Scene Detection or Software Global Monitors.
Anomalous shutdowns can also occur as a result of MAMA hardware
problems. The Initial MAMA turn-on/recovery from anomalous shutdown
consists of three tests: a signal processing electronics check, high
voltage ramp-up to an intermediate voltage, and high voltage ramp-up
to the full operating voltage. During each of the two high voltage
ramp-ups, diagnostics are performed during a dark ACCUM. The turn-on
is followed by a MAMA Fold Analysis . The complete sequence is
contained in visits 1 through 4. If a second execution is required
during cycle 13, visits 5 through 8 will be run and another proposal
prepared for possible future occurrences.
WFPC2 10745
WFPC2 CYCLE 14 INTERNAL MONITOR
This calibration proposal is the Cycle 14 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.
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:
#17852-0 - GenSlew for Proposal 10598 slot#13 @200/1621z
#17853-0 - GenSlew for Proposal 10598 slot#14 @200/1821z
#17854-0 - GenSlew for Proposal 10598 slot#1 @200/1957z
#17857-0 - GenSlew for Proposal 10598 slot#2 @200/2149z
#17855-1 - Clear ACS Event Flag 2 @199/1818z
#17856-0 - Restore VTFE to K1L4 @199/2012z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 12 12
FGS REacq 04 04
OBAD with Maneuver 28 28
SIGNIFICANT EVENTS: (None)
Raised VTFE to K1L4 Flash Report
At approximately DOY 199/2012 GMT (Tuesday, 7/18, 4:12pm local), the
VTFE was reset to the nominal K1L4 level. (The VTFE had been reduced
to K1L4-150mV on DOY 196. Additionally, the +CC SPA was taken
off-line.) EPS will determine the appropriate time to place the +CC
SPA back on-line.
.
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