Status Report

NASA Hubble Space Telescope Daily Report #4157

By SpaceRef Editor
July 19, 2006
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NASA Hubble Space Telescope Daily Report #4157

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT July 17, 2006 (DOY 198)


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 10801

Direct Determination of Kuiper Belt Object Diameters with HST

When it comes to fundamental properties of an astronomical object, it is difficult to think of a more fundamental physical property than its size. Because of their distance, objects in the Kuiper Belt are generally too small for their disks to be resolved. The heterogeneous albedo and color of the Kuiper Belt population makes size estimates from observed absolute magnitude highly uncertain. And the long-awaited data from the Spitzer Space Telescope suffers from our ignorance of crucial macro- and micro-physical properties such as spin period, pole orientation, surface roughness, and thermal inertia. We propose to add a new dimension to the measurement of KBO diameters by employing two techniques that will directly measure the diameters of three large KBOs. We expect to obtain diameter measurements with uncertainties of 10% or better and utilize these to validate and cross calibrate the growing web of diameter measurements for KBOs.

ACS/HRC 11004

The 2006 outburst of RS Oph – A rapidly evolving SNR analogue with jets

We propose to use HST DD time to perform high resolution optical imaging of the 2006 outburst of the Recurrent Nova RS Ophiuchi, which underwent its last recorded outburst in 1985. In this system, high velocity ejecta impact a red giant wind setting up shock systems analogous to a SNR, but evolving on months timescales. HST observations will complement our multi-frequency observing campaign, in particular our unrivalled coverage of this event with VLBI. In the radio, we have resolved on AU scales the expanding shock front responsible for the X-ray emission seen in the data from 4 satellites. We have also detected jets on 0.1 arcsec scales. HST ACS HRC imaging will be uniquely valuable in disentangling different emission components and deriving physical conditions.


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.


An Efficient ACS Coronagraphic Survey for Debris Disks around Nearby Stars

We propose to finish our Cycle 11 optical survey for nearby debris disks using the ACS/HRC coronagraph. Out of 43 orbits originally proposed for the survey, 23 orbits were allocated, leading to a survey of 22 stars, from which two new debris disks were imaged for the first time. Our analysis of the initial survey gives an empirical estimate for the detection rate of debris disks relative to heliocentric distance and dust optical depth. Our target list for Cycle 15 is now optimized to yield more frequent disk detections. Likewise our observing strategy is improved to maximize sensitivity per telescope orbit allocated. Therefore we present the most efficient survey possible. The scientific motivation is to obtain scattered light images of previously unresolved debris disks to determine their viewing geometry and physical architecture, both of which may characterize the underlying planetary system. We choose 25 debris disk targets for which we predict a detection rate of 25% ? 5%. Four targets have extrasolar planets from which the viewing geometry revealed by a disk detection will resolve the v sin{i} ambiguity in the planet masses. These targets present the remarkable opportunity of finally seeing a debris disk in system with known planets.

ACS/WFC 10490

A Snapshot Survey of a Complete Sample of X-ray Luminous Galaxy Clusters from Redshift 0.3 to 0.7 We propose to extend a public, uniform imaging survey of a well-studied, complete, and homogeneous sample of X-ray clusters. The sample of 72 clusters spans the redshift range between 0.3-0.7 and almost 2 orders of magnitude of X-ray luminosity, with a median luminosity of 10^44 erg/s {0.5-2.0 keV}. These snapshots will be used to obtain a fair census of the morphologies of cluster galaxies in the cores of intermediate redshift clusters, to detect radial and tangential arc candidates, to detect optical jet candidates, and to provide an approximate estimate of the shear signal of the clusters themselves and a potential assessment of the contribution of large scale structure to lensing shear.

ACS/WFC 10587

Measuring the Mass Dependence of Early-Type Galaxy Structure

We propose two-color ACS-WFC Snapshot observations of a sample of 118 candidate early-type gravitational lens galaxies. Our lens-candidate sample is selected to yield {in combination with earlier results} an approximately uniform final distribution of 40 early-type strong lenses across a wide range of masses, with velocity dispersions {a dynamical proxy for mass} ranging from 125 to 300 km/s. The proposed program will deliver the first significant sample of low-mass gravitational lenses. All of our candidates have known lens and source redshifts from Sloan Digital Sky Survey data, and all are bright enough to permit detailed photometric and stellar-dynamical observation. We will constrain the luminous and dark-matter mass profiles of confirmed lenses using lensed-image geometry and lens-galaxy structural/photometric measurements from HST imaging in combination with dynamical measurements from spatially resolved ground-based follow- up spectroscopy. Hence we will determine, in unprecedented detail, the dependence of early-type galaxy mass structure and mass-to-light ratio upon galaxy mass. These results will allow us to directly test theoretical predictions for halo concentration and star-formation efficiency as a function of mass and for the existence of a cuspy inner dark-matter component, and will illuminate the structural explanation behind the fundamental plane of early-type galaxies. The lens-candidate selection and confirmation strategy that we propose has been proven successful for high-mass galaxies by our Cycle 13 Snapshot program {10174}. The program that we propose here will produce a complementary and unprecedented lens sample spanning a wide range of lens-galaxy masses.

ACS/WFC 10624

Solving the Mystery of the Short-Hard Gamma-Ray Bursts

Eight years after the afterglow detections that revolutionized studies of the long-soft gamma-ray bursts, not even one afterglow of a short-hard GRB has been seen, and the nature of these events has become one of the most important problems in GRB research. The Swift satellite, expected to be in full operation throughout Cycle 14, will report few- arcsecond localizations for short-hard bursts in minutes, enabling prompt, deep optical afterglow searches for the first time. Discovery and observation of the first short-hard optical afterglows will answer most of the critical questions about these events: What are their distances and energies? Do they occur in distant galaxies, and if so, in which regions of those galaxies? Are they the result of collimated or quasi-spherical explosions? In combination with an extensive rapid-response ground-based campaign, we propose to make the critical high-sensitivity HST TOO observations that will allow us to answer these questions. If theorists are correct in attributing the short-hard bursts to binary neutron star coalescence events, then they will serve as signposts to the primary targeted source population for ground-based gravitational-wave detectors, and short-hard burst studies will have a vital role to play in guiding those observations.

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.


SBC Filter Wheel Checkout

In the event of an ACS Side 1 electronics failure we will switch to Side 2. Several tests will be performed before resuming normal operations. The following proposal is one of these and should be held until the Side2 switch becomes necessary. This proposal’s purpose is to command the SBC Filter Wheel to each of its positions in both directions of motion and verify {via the mechanism’s positional encoding readout} proper execution of the commands.

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 10748

WFPC2 CYCLE 14 Standard Darks

This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs.


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


10365 – Reacq(1,2,1) results in finelock backup @198/1007z

During LOS REacq(1,2,1) scheduled at 198/10:06:39 rsulted in finelock backup (1,0,1) due to a stop flag (QF2STOPF) on FGS 2. Observations affected: ACS 38-41

10366 – Error Received while processing SAC-97 Procedure @197/1620z

After generating the engineering file for the SAC-97 – Gyro Bias Trending: On Board Bias Validation procedure, an error was received running the ‘Trending Option of RGACAL’. The original time frame for the engineering file covered the period 2006/189 00:00:00 to 197 00:00:00Z. The title of the error received is ‘RAW DATA PROCESSING ERROR’ – error 30 accessing raw data file – message #3840.

10367 – Correctable Edac Errors @199/0420z

During Science Playback on SSR-1 we received 1363 Edacs from an expected area already containing 131 errors. This total was generated during a block range of approximately 16479 – 18099. After the On Call SE was notified, FOT proceeded to redump the anamolous area and received 1347 Edacs. These errors did not occur during an SAA. Fot will notify SE when this area is written over and redumped.


  • 17838-0 – GenSlew for Proposal 10598 slot#13 @198/1531z
  • 17839-0 – GenSlew for Proposal 10598 slot#14 @198/1533z
  • 17840-0 – GenSlew for Proposal 10598 slot#1 @198/1534z
  • 17841-0 – GenSlew for Proposal 10598 slot#2 @198/1535z
  • 17842-0 – GenSlew for Proposal 10598 slot#3 @198/1537z
  • 17843-0 – GenSlew for Proposal 10598 slot#4 @198/1539z
  • 17844-0 – GenSlew for Proposal 10598 slot#5 @198/2050z
  • 17845-0 – GenSlew for Proposal 10598 slot#6 @198/2053z
  • 17846-0 – GenSlew for Proposal 10598 slot#7 @198/2055z
  • 17847-0 – GenSlew for Proposal 10598 slot#8 @198/2057z
  • 17848-0 – GenSlew for Proposal 10598 slot#9 @198/2059z
  • 17849-0 – GenSlew for Proposal 10598 slot#10 @198/2101z
  • 17850-0 – GenSlew for Proposal 10598 slot#11 @198/2103z
  • 17851-0 – GenSlew for Proposal 10598 slot#12 @198/2136z
  • 17837-0 – CONTINGENCY: Disconnect and Mask the +CC SPA @199/0120z


1508-1 – Battery Temperature Reaches 8 degC @199/0120z

                            SCHEDULED SUCCESSFUL 
FGS GSacq                  12                12 
FGS REacq                   02                02 
OBAD with Maneuver     26                 26 


Offlined +CC SPA (K1A Trim Relay on Battery 6) Flash Report At approximately doy 199 / 01:20 GMT (Monday, 7/17, 920pm local), the +CC SPA was offlined to reduce battery 6 temperature. Battery 6 temperature had exceeded +8.4degC. EPS SE verified that the benchmark reset threshold was reached on the following orbit and that the battery 6 temperature had decreased by about 2degC relative to battery 5.

SpaceRef staff editor.