Status Report

NASA Hubble Space Telescope Daily Report #4158

By SpaceRef Editor
July 19, 2006
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NASA Hubble Space Telescope Daily Report #4158
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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.

SpaceRef staff editor.