Status Report

NASA Hubble Space Telescope Daily Report #4159

By SpaceRef Editor
July 20, 2006
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NASA Hubble Space Telescope Daily Report #4159
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT # 4159

PERIOD COVERED: UT July 19, 2006 (DOY 200)

OBSERVATIONS SCHEDULED

ACS/HRC 10512

Search for Binaries Among Faint Jupiter Trojan Asteroids

We propose an ambitious SNAPSHOT program to survey faint Jupiter Trojan asteroids for binary companions. We target 150 objects, with the expectation of acquiring data on about 50%. These objects span Vmag = 17.5-19.5, a range inaccessible with ground-based adaptive optics. We now have a significant sample from our survey of brighter Trojans to suggest that the binary fraction is similar to that which we find among brighter main-belt asteroids, roughly 2%. However, our observations suggest a higher binary fraction for smaller main-belt asteroids, probably the result of a different formation mechanism {evident also from the physical characteristics of the binaries}. Because the collision environment among the Trojans is similar to that of the Main Belt, while the composition is likely to be very different, sampling the binary fraction among the fainter Trojans should help us understand the collisional and binary formation mechanisms at work in various populations, including the Kuiper Belt, and help us evaluate theories for the origin of the Trojans. Calibration of and constraints on models of binary production and collisional evolution can only be done using these large-scale, real-life physical systems that we are beginning now to find and utilize.

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 10627

A Snapshot Survey of Post-AGB Objects and Proto-Planetary Nebulae

We propose an ACS/HRC snapshot survey of 50 post-AGB sources, objects which have evolved from the AGB but may or may not become planetary nebulae {PNe}. This survey will complement existing HST images of proto-planetary nebulae {PPNe} and PNe in addressing circumstellar envelope morphology as a function of: 1} the progenitor star mass; 2} the chemical composition; and 3} evolutionary stage. We will connect the observed diversity of nebualar shapes with the main physical and chemical conditions characterizing post-AGB objects, to identify the mechanism that breaks the symmetry of AGB mass loss. To our knowledge, no previous HST projects have been specifically designed to address this issue. From our database of 360 post-AGB candidates, we have selected approximately 50 targets, none of which have been or are being observed with HST, to sample different central star masses, chemical compositions, and evolutionary stages, uniformly across the sky. These new data will also provide important constraints to a quantitative analysis of Spitzer Space Telescope {SST} observations planned for a similar sample of objects. We will model the HST images and SST spectra using our axisymmetric dust code 2-Dust, to derive dust density distributions, pole to equator density ratios, dust shell masses, inclination angles as well as dust composition.

ACS/HRC/WFC 10758

ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC is 2 e- /DN. As before bias frames will be collected for both gain 1 and gain 2. Dark frames are acquired using the default gain {2}. This program cover the period May, 31 2006- Oct, 1- 2006. The first half of the program has a different proposal number: 10729.

ACS/WFC 10626

A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to z = 0.9

We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy clusters at 0.3 < z < 0.9 from the Red Sequence Cluster Survey {RCS}. An examination of the galaxian light in the brightest cluster galaxies, coupled with a statistical analysis of the strong- lensing properties of the sample, will allow us to contrain the evolution of both the baryonic and dark mass in cluster cores, over an unprecedented redshift range and sample size. In detail, we will use the high-resolution ACS images to measure the metric {10 kpc/h} luminosity and morphological disturbances around the brightest clusters galaxies, in order to calibrate their accretion history in comparison to recent detailed simulations of structure formation in cluster cores. These images will also yield a well-defined sample of arcs formed by strong lensing by these clusters; the frequency and detailed distribution {size, multiplicity, redshifts} of these strong lens systems sets strong constraints on the total mass content {and its structure} in the centers of the clusters. These data will also be invaluable in the study of the morphological evolution and properties of cluster galaxies over a significant redshift range. These analyses will be supported by extensive ongoing optical and near-infrared imaging, and optical spectroscopy at Magellan, VLT and Gemini telescopes, as well as host of smaller facilities.

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 .

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 10906

The Fundamental Plane of Massive Gas-Rich Mergers: II. The QUEST QSOs

We propose deep NICMOS H-band imaging of a carefully selected sample of 23 local QSOs. This program is the last critical element of a comprehensive investigation of the most luminous mergers in the nearby universe, the ultraluminous infrared galaxies {ULIRGs} and the quasars. This effort is called QUEST: Quasar / ULIRG Evolutionary STudy. The high-resolution HST images of the QUEST QSOs will complement an identical set of images on the ULIRG sample obtained during Cycle 12, an extensive set of ground-based data that include long-slit NIR spectra from a Large VLT Program, and a large set of mid-infrared spectra from a Cycle 1 medium-size program with Spitzer. This unique dataset will allow us to derive with unprecedented precision structual, kinematic, and activity parameters for a large unbiased sample of objects spanning the entire ULIRG/QSO luminosity function. These data will refine the fundamental plane of massive gas-rich mergers and enable us to answer the following quesitons: {1} Do ultraluminous mergers form elliptical galaxies, and in particular, giant ellipticals? {2} Do ULIRGs evolve into optical bright QSOs? The results from this detailed study of massive mergers in the local universe will be relevant to understanding the basic physical processes involved in creating massive early-type host on the one hand, and growing/feeding embedded massive black holes on the other, in major galaxy mergers. This is an important question since 50% of cosmic star formation at high-z and most of the big BHs appear to be formed in this process.

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:

#17859-0 GenSlew for Proposal 10487 slot#3 @200/18:51z

#17860-0 GenSlew for Proposal 10487 slot#4 @200/18:53z

COMPLETED OPS NOTES: (None)

                        SCHEDULED          SUCCESSFUL 
FGS 
GSacq                  13                13 
FGS REacq                  00                00 
OBAD with Maneuver     26                26 

SIGNIFICANT EVENTS: (None)

SpaceRef staff editor.