Status Report

NASA Hubble Space Telescope Daily Report #4378

By SpaceRef Editor
June 7, 2007
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NASA Hubble Space Telescope Daily Report #4378

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

PERIOD COVERED: UT June 06, 2007 (DOY 157)


WFPC2 10833

Host Galaxies of Reverberation Mapped AGNs

We propose to obtain unsaturated high-resolution images of 17 reverberation-mapped active galactic nuclei in order to remove the point-like nuclear light from each image, thus yielding a “nucleus-free” image of the host galaxy. This will allow investigation of host galaxy properties: our particular interest is determination of the host-galaxy starlight contribution to the reverberation-mapping observations. This is necessary {1} for accurate determination of the relationship between the AGN nuclear continuum flux and the size of the broad Balmer-line emitting regions of AGNs, which is important in estimating black hole masses for large samples of QSOs, and {2} for accurate determination of the bolometric luminosity of the AGN proper. Through observations in Cycles 12 and 14, we have obtained or will obtain images of 18 of the 35 objects in the reverberation-mapping compilation of Peterson et al. {2004}. These observations revealed that the host-galaxy contribution, even in the higher-luminosity AGNs, is higher than expected and that all of the reverberation- mapped AGNs will have to be observed, not just the lower-luminosity sources; each source is different, and each source is important. Therefore we request time to observe the 17 remaining reverberation-mapped AGNs.

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}.

NIC2 10798

Dark Halos and Substructure from Arcs & Einstein Rings

The surface brightness distribution of extended gravitationally lensed arcs and Einstein rings contains super-resolved information about the lensed object, and, more excitingly, about the smooth and clumpy mass distribution of the lens galaxies. The source and lens information can non-parametrically be separated, resulting in a direct “gravitational image” of the inner mass-distribution of cosmologically-distant galaxies {Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}. With this goal in mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W WFC imaging of 20 new gravitational-lens systems with spatially resolved lensed sources, of the 35 new lens systems discovered by the Sloan Lens ACS Survey {Bolton et al. 2005} so far, 15 of which are being imaged in Cycle-14. Each system has been selected from the SDSS and confirmed in two time- efficient HST-ACS snapshot programs {cycle 13&14}. High-fidelity multi-color HST images are required {not delivered by the 420s snapshots} to isolate these lensed images {properly cleaned, dithered and extinction-corrected} from the lens galaxy surface brightness distribution, and apply our “gravitational maging” technique. Our sample of 35 early-type lens galaxies to date is by far the largest, still growing, and most uniformly selected. This minimizes selection biases and small-number statistics, compared to smaller, often serendipitously discovered, samples. Moreover, using the WFC provides information on the field around the lens, higher S/N and a better understood PSF, compared with the HRC, and one retains high spatial resolution through drizzling. The sample of galaxy mass distributions – determined through this method from the arcs and Einstein ring HST images – will be studied to: {i} measure the smooth mass distribution of the lens galaxies {dark and luminous mass are separated using the HST images and the stellar M/L values derived from a joint stellar-dynamical analysis of each system}; {ii} quantify statistically and individually the incidence of mass-substructure {with or without obvious luminous counter- parts such as dwarf galaxies}. Since dark-matter substructure could be more prevalent at higher redshift, both results provide a direct test of this prediction of the CDM hierarchical structure-formation model.

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 11155

Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging and Polarimetry

We propose to take advantage of the sensitive coronagraphic capabilities of NICMOS to obtain multiwavelength coronagraphic imaging and polarimetry of primordial dust disks around young intermediate-mass stars {Herbig Ae stars}, in order to advance our understanding of how dust grains are assembled into larger bodies. Because the polarization of scattered light is strongly dependent on scattering particle size and composition, coronagraphic imaging polarimetry with NICMOS provides a uniquely powerful tool for measuring grain properties in spatially resolved circumstellar disks. It is widely believed that planets form via the gradual accretion of planetesimals in gas-rich, dusty circumstellar disks, but the connection between this suspected process and the circumstellar disks that we can now observe around other stars remains very uncertain. Our proposed observations, together with powerful 3-D radiative transfer codes, will enable us to quantitatively determine dust grain properties as a function of location within disks, and thus to test whether dust grains around young stars are in fact growing in size during the putative planet-formation epoch. HST imaging polarimetry of Herbig Ae stars will complement and extend existing polarimetric studies of disks around lower-mass T Tauri stars and debris disks around older main-sequence stars. When combined with these previous studies, the proposed research will help us establish the influence of stellar mass on the growth of dust grains into larger planetesimals, and ultimately to planets. Our results will also let us calibrate models of the thermal emission from these disks, a critical need for validating the properties of more distant disks inferred on the basis of spectral information alone.

WFPC2 10902

The Nearest Luminous Blue Compact Galaxies: A Window on Galaxy Formation

As we move to intermediate and high redshifts, Luminous Blue Compact Galaxies {LBCGs} become increasingly common. The nearest LBCGs, with their violent starbursts and rich populations of super star clusters {SSCs} and globular clusters {GCs}, thus provide ideal laboratories for studying galaxy evolution. Many LBCGs appear to be involved in mergers between dwarf galaxies, triggering their starbursts. The starburst regions in LBCGs consist of numerous young star clusters, whose populations are both easily measurable with HST and easily modelled. Studying cluster populations provides a powerful probe of the starburst and merger history which is possible neither for closer objects {of which there are too few} or for those at high redshift {which are too far away}. We have previously studied the closest LBCG with WFPC2 and found hundreds of bright compact SSCs and GCs. In particular, we found a population of intermediate-age {~2 Gyr} GCs, indicating a past event of massive cluster formation. We now propose a multi-wavelength study of the three other LBCGs with the highest known number of SSCs. The extinction is small in these galaxies and age estimates robust. The age distribution of GCs and SSCs will be used to study the past evolution of the galaxies. For each LBCG, we will map its cluster formation history, unveiling its merger and starburst history, and thereby shed light on some of the processes involved in galaxy evolution at high redshift.

WFPC2 11032

CTE Extended Targets Closeout

Measuring the charge transfer efficiency {CTE} of an astronomical CCD camera is crucial to determining the CCD’s photometric fidelity across the field of view. WFPC2’s CTE has degraded steadily over the last 13 years because of continuous exposure to trapped particles in HST’s radiation environment. The fraction of photometric signal lost from WFPC2’s CTI {change transfer inefficiency} is a function of WFPC2’s time in orbit, the integrated signal in the image, the location of the image on the CCD, and the background signal. Routine monitoring of WFPC2’s degrading CTE over the last 13 years has primarily concerned the effects of CTI on point-source photometry. However, most of the sources imaged by WFPC2 are extended rather than point-like. This program aims to characterize the effects of CTI on the photometry and morphology of extended sources near the end of WFPC2’s functional life. Images of a standard field within the rich galaxy cluster Abell 1689 are recorded with each WFPC2 camera using the F606W and F814W filters. These images will be compared with contemporaneous images of Abell 1689 recorded with the field rotated by approximately 180 degrees to assess differences between extended sources imaged near and far from the serial register. The images will also be compared with similar images recorded in Cycle 8 {Program 8456} to characterize the rate of CTE degradation over the lifetime of WFPC2.


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

10851 – NICMOS suspended.

Upon acquisition of signal at 05:46:44 NICMOS was suspended with a status buffer message NICMOS 632, parameter = 210, time = 43954, indicating “MECH_2_MAX_RETRIES_EXCEEDED”. The number of positioning error retries attempted during a Filter Wheel 2 movement exceeded the maximum limit. Actual time of status buffer message was 05:14:05. COMPLETED OPS REQUEST: (None)


                             SCHEDULED    SUCCESSFUL 
FGS GSacq                      8                  8 
FGS REacq                      3                  3 
OBAD with Maneuver            20                 20 


SpaceRef staff editor.