Status Report

NASA Hubble Space Telescope Daily Report #4362

By SpaceRef Editor
May 15, 2007
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NASA Hubble Space Telescope Daily Report #4362

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.


– Continuing to collect World Class Science


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.

WFPC2 10832

Solving the microlensing puzzle: An HST high-resolution imaging approach

We propose to use the HST Advanced Camera for Surveys High Resolution Channel to obtain high resolution imaging data for 10 bona-fide LMC microlensing events seen in the original MACHO survey. The purpose of this survey will be to assess whether or not the lens and source stars have separated enough to be resolved since the original microlensing event took place – about a decade has passed since the original MACHO survey and the HST WFPC2 follow-up observations of the microlensing events. If the components of the lensing event are resolved, we will determine the apparent magnitude and color of both the lens and the source stars. These data, in combination with Spitzer/IRAC data and Magellan near-IR JHK data, will be used to ascertain the basic properties of the lens stars. With the majority of the microlensing events in the original MACHO survey observed at the highest spatial resolution currently possible, we will be able to draw important conclusions as to what fraction of these events have lenses which belong to some population of dwarf stars in the disk and what fraction must be due to lenses in the halo or beyond. These data will greatly increase our understanding of the structure of the Galaxy by characterizing the stellar population responsible for the gravitational microlensing.

ACS/SBC 10862

Comprehensive Auroral Imaging of Jupiter and Saturn during the International Heliophysical Year

A comprehensive set of observations of the auroral emissions from Jupiter and Saturn is proposed for the International Heliophysical Year in 2007, a unique period of especially concentrated measurements of space physics phenomena throughout the solar system. We propose to determine the physical relationship of the various auroral processes at Jupiter and Saturn with conditions in the solar wind at each planet. This can be accomplished with campaigns of observations, with a sampling interval not to exceed one day, covering at least one solar rotation. The solar wind plasma density approaching Jupiter will be measured by the New Horizons spacecraft, and a separate campaign near opposition in May 2007 will determine the effect of large-scale variations in the interplanetary magnetic field {IMF} on the Jovian aurora by extrapolation from near-Earth solar wind measurements. A similar Saturn campaign near opposition in Jan. 2007 will combine extrapolated solar wind data with measurements from a wide range of locations within the Saturn magnetosphere by Cassini. In the course of making these observations, it will be possible to fully map the auroral footprints of Io and the other satellites to determine both the local magnetic field geometry and the controlling factors in the electromagnetic interaction of each satellite with the corotating magnetic field and plasma density. Also in the course of making these observations, the auroral emission properties will be compared with the properties of the near-IR ionospheric emissions {from ground-based observations} and non thermal radio emissions, from ground-based observations for Jupiter?s decametric radiation and Cassini plasma wave measurements of the Saturn Kilometric Radiation {SKR}.

WFPC2 10880

The host galaxies of QSO2s: AGN feeding and evolution at high luminosities

Now that the presence of supermassive black holes in the nuclei of galaxies is a well established fact, other questions related to the AGN phenomena still have to be answered. Problems of particular interest are how the AGN gets fed, how the black hole evolves and how the evolution of the black hole is related to the evolution of the galaxy bulge. Here we propose to address some of these issues using ACS/WFC + F775W snapshot images of 73 QSO2s with redshifts in the range 0.3< z <0.4. These observations will be combined with similar archival data of QSO1s and ground based data of Seyfert and normal galaxies. First, we will intestigate whether interactions are the most important feeding mechanism in high luminosity AGNs. This will be done in a quantitative way, comparing the asymmetry indices of QSO2 hosts with those of lower luminosity AGNs and normal galaxies. Second, we will do a detailed study of the morphology of the host galaxies of both QSO types, to determine if they are similar, or if there is an evolutionary trend from QSO2s to QSO1s. The results from this project will represent an important step in the understanding of AGN evolution, and may also introduce a substantial modification to the Unified Model.

WFPC2 11024


This calibration proposal is the Cycle 15 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.

WFPC2 10889

The Nature of the Halos and Thick Disks of Spiral Galaxies

We propose to resolve the extra-planar stellar populations of the thick disks and halos of seven nearby, massive, edge-on galaxies using ACS, NICMOS, and WFPC2 in parallel. These observations will provide accurate star counts and color-magnitude diagrams 1.5 magnitudes below the tip of the Red Giant Branch sampled along the two principal axes and one intermediate axis of each galaxy. We will measure the metallicity distribution functions and stellar density profiles from star counts down to very low average surface brightnesses, equivalent to ~32 V-mag per square arcsec. These observations will provide the definitive HST study of extra-planar stellar populations of spiral galaxies. Our targets cover a range in galaxy mass, luminosity, and morphology and as function of these galaxy properties we will provide: – The first systematic study of the radial and isophotal shapes of the diffuse stellar halos of spiral galaxies – The most detailed comparative study to date of thick disk morphologies and stellar populations – A comprehensive analysis of halo and thick disk metallicity distributions as a function of galaxy type and position within the galaxy. – A sensitive search for tidal streams – The first opportunity to directly relate globular cluster systems to their field stellar population We will use these fossil records of the galaxy assembly process preserved in the old stellar populations to test halo and thick disk formation models within the hierarchical galaxy formation scheme. We will test LambdaCDM predictions on sub-galactic scales, where it is difficult to test using CMB and galaxy redshift surveys, and where it faces its most serious difficulties.

WFPC2 10799

Photometric Mapping of Vesta’s Southern Hemisphere

We propose to image asteroid 4 Vesta throughout one complete rotation during its opposition and close approach to Earth in May of 2007 in four filters for the purposes of improving knowledge of its spin pole, size, shape, albedo and composition across its surface. We will conduct a satellite search. Multi-filter imaging will extend the range of photometric mapping into the southern hemisphere where a large basin exists, and will extend compositional mapping further into the southern hemisphere than previous observations. The results will improve our understanding of protoplanetary processes and support scientific planning for NASA’s Dawn mission to orbit Vesta 2011.

WFPC2 10903

Resolving the LMC Microlensing Puzzle: Where are the Lensing Objects?

We are requesting 12 HST orbits to continue to investigate the nature of the population that gives rise to the microlensing seen towards the LMC. This proposal builds on the cycle 14 HST program {10583} and will complement the study with 12 yet-to-be discovered microlensing candidates from Fall 2006. Our SuperMacho project is an ongoing ground- based survey on the CTIO 4m that has demonstrated the ability to detect LMC microlensing events via frame subtraction. The combination of high angular resolution and photometric accuracy with HST will allow us to 1} confrim that the detected flux excursions arise from LMC stars, rather than background supernovae or AGN, and 2} obtain reliable baseline flux measurements for the objects in their unlensed state. This latter measurement in important in determining the microlensing optical depth towards the LMC.

WFPC2 11023

WFPC2 CYCLE 15 Standard Darks – part 1

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.)

HSTARS: (None)


  • 18081-0 – PCS KF OOT Support
  • 18078-0 – MSS Only KF Converged & Add Gyro2, Test #38 for day 134
  • 18082-0 – PCS KF OOT Support
  • 18079-0 – MSS/CSS Initialization Test #6 for day 134
  • 18054-0 – Preview KF Sun Vector Data via Telemetry Diags,
  • 18080-0 – MSS/CSS/Gyro1 Initialization Test #16 for day 134


                      SCHEDULED      SUCCESSFUL 
FGS GSacq               10                 10 
FGS REacq               02                 02 
OBAD with Maneuver      24                 24 


Evaluation of Universal Kalman Filter performance continued. Multiple text segments were executed, all of them successfully. Details follow. Background Kalman Filter Operation Flash Report for day 134 The Gyro2 sensor input was added to the KF at 134/12:55. The input was added during a vehicle slew, an M2G guiding interval and a slow changing B-field. The filter was already converged with only MSS sensor input. All UKF parameters showed nominal operation. The test was an MSS converged test case with Gyro2 sensor input added during a vehicle slew and a slow changing B-field (M_G2_RVS, Test #38). The Gyro2 sensor input was removed at 13:41 to restore the current configuration of MSS only input.

The KF was halted at 134/14:38. It was restarted at 134/14:40 with the MSS and CSS sensor inputs enabled. The initialization occurred during orbit day, during a vehicle slew and during a slow changing B-field. All UKF parameters showed nominal operation. The test was an MSS/CSS Initialization test case during a slow changing B-field and during a vehicle slew (M_C_IVS, Test #6). The filter remained in this configuration up to the next test period below. The KF was halted at 134/16:17. It was restarted at 134/16:24 with the MSS, CSS and Gyro1 sensor input enabled. The initialization occurred during orbit day, during a slow changing B-field and during a vehicle maneuver. All UKF parameters showed nominal operation. The test was an MSS/CSS/Gyro1 Initialization test case during a slow changing B-field and during a vehicle maneuver (MC_G1_IVS, Test #16). The filter was halted and reconfigured to use only MSS sensor input at 134/16:43.

This completes the KF convergence testing for this week. It is necessary to allow the orbit to process to place the fast and slow changing B-field periods during operational working hours. The KF has been placed into the MSS only sensor input to provide data for one of the long-term (~1 week) test cases.

SpaceRef staff editor.