Status Report

NASA Hubble Space Telescope Daily Status Report #4056

By SpaceRef Editor
February 23, 2006
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NASA Hubble Space Telescope Daily Status Report #4056

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT February 22, 2006 (DOY 053)


ACS/HRC 10516

Host Galaxies of Reverberation-Mapped AGNs

We propose to obtain unsaturated ACS high-resolution images of four 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 because this relationship is used in estimating black hole masses for large samples of QSOs, and {2} for accurate determination of the bolometric luminosity of the AGN proper. In a Cycle 12 SNAP program, we obtained images of 14 of the 36 reverberation-mapped AGNs for this purpose. This additional request is to complete this program through observations of the four important remaining sources.

ACS/HRC 10623

HST Optical Snapshot Survey of Intermediate Redshift Ultraluminous Infrared Galaxies

Ultraluminous infrared galaxies {ULIGs} are commonly believed to be a transitory phase in the evolution of disk galaxy mergers into QSOs. However, a recently reported discrepancy between the morphological and structural properties of z < 0.13 ULIGs and z = 0.12-0.25 QSOs with M{V} < -23.5 has cast doubt on their evolutionary connection. We propose an ACS snapshot survey of a sample of 39 ULIGs with z = 0.35-1.0. These galaxies are the best suited for comparison with luminous z=0.12-0.25 QSOs because {1} they are at larger lookback times than local ULIGs, and thus are likely representative of the systems that evolve into lower redshift luminous QSOs, {2} they have luminosities comparable to luminous QSOs and, {3} they are selected in a manner that biases the sample towards harboring imbedded AGN, and thus are the most likely precursors to optical QSOs. High resolution HST ACS images will allow a determination of galaxy morphology and reveal the presence of bright AGN. The 2-D profile of each galaxy will be modeled using GALFIT, with the AGN comprising one component of the fit where applicable to better characterize the underlying galaxy. Fundamental parameters {effective radius and surface brightness, and F814W-band magnitude} of the underlying galaxy will thus be measured and compared with the host galaxies of the luminous QSO sample. This imaging campaign will consume a modest amount of HST time, but will provide for the first time a statistically significant view of ULIGs at look-back times of 30-65% the age of the universe, and sufficient resolution and sensitivity to conduct a meaningful comparison with z=0.12-0.25 QSOs, as well as with local {z < 0.3} IRAS-detected and distant {z > 2} SCUBA-detected ULIGs.


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 Oct, 2 2005- May, 29-2006. The second half of the program has a different proposal number: 10758.

ACS/WFC 10574

Witnessing Galaxy Transformation in Galaxy Groups at z > 1

The recent discover of five galaxy groups in the Lynx supercluster region offers us the exciting opportunity to observe for the first time groups in the process of collapsing into a merging pair of clusters at z > 1. Our current picture of structure formation suggests that substantial evolution of galaxy properties can occur in groups and filaments well before they enter the environs of massive clusters. However, neither current theoretical models nor observations give us a complete understanding of the relative importance of the different physical processes that control the structural and spectral transformations that occur prior to, during, and after infall into a dense environment. We propose direct observation of these newly discovered dynamically young structures in the Lynx region, in order to provide a critical benchmark in testing not only whether galaxy evolution occurs mostly prior to entry into the densest regions but will also constrain the relative importance of initial conditions in determining the fate of galaxy systems. Our analysis of these proposed ACS measurements will be complemented with an unique dataset we have already in the optical, infrared, mid-infrared, and X-ray.

WFPC2 10608

Probing the star formation law in the extreme outer limits of M83, a prototypical XUV-disk galaxy

The Galaxy Evolution Explorer {GALEX} has discovered a new sub-class of spiral galaxy, which we refer to as extended UV-disk {XUV-disk} galaxies. They are distinguished by conspicuous UV-bright star clusters located at galactocentric radii extending to many times the optical {R25} extent, and appear to represent a population of spiral galaxies still actively building, or augmenting, their stellar disk. However, XUV-disks pose a mystery in the form of a relative lack of HII regions {traced by H-alpha emission} associated with outer disk, UV-bright stellar clusters. M83 is an XUV-disk prototype and the focus of this proposal. It has an H-alpha surface brightness profile characterized by a steep decline at the radius beyond which the gaseous disk is thought to become dynamically stable {against collapse and ensuing star formation}, but GALEX UV profiles show no “edge” at this location. Our HST study of M83 aims to resolve this puzzling discrepancy, confirmed in several XUV-disks, by searching for Lyman-continuum producing O stars that are either absent or present without nebulosity. HST provides the only means of resolving individual massive stars in the FUV band at M83’s distance. Without HST, we lose the critical ability to photometrically classify O and B stars. Our multiwavelength observations will also constrain the history of star formation in the outer disk over Gyr timescales by characterizing the evolved stellar population, both using resolved giants and color analysis of the diffuse background.

WFPC2 10779

WFPC2 WF4 Temperature Reduction Test #2

A serious anomaly has been found in images from the WF4 CCD in WFPC2. The WF4 CCD bias level appears to have become unstable, resulting in sporadic images with either low or zero bias level. The severity and frequency of the problem is rapidly increasing, and it is possible that WF4 will soon become unusable if no work-around is found. The other three CCDs {PC1, WF2, and WF3} appear to be unaffected and continue to operate properly. This is a second test to further reduce temperatures. Orbits: internal 26, external 1


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


10144 – GSAcq(1,3,1) requires multiple attempts to achieve CTDV @ 049/2346z

Review of PTAS data revealed that GSAcq(1,3,1), scheduled for 2006/049 23:45:36 required three entries into CT before achieving CT-DV.


  • 17649-0 – Genslew for Proposal 10599 – Slot#7 @053/1708z
  • 17650-0 – Genslew for Proposal 10599 – Slot#8 @053/1710z
  • 17651-0 – Genslew for Proposal 10599 – Slot#9 @053/1711z
  • 17652-0 – Genslew for Proposal 10599 – Slot#11 @053/1712z
  • 17653-0 – Genslew for Proposal 10599 – Slot#10 @053/1714z
  • 17654-0 – Genslew for Proposal 10599 – Slot#14 @053/1715z
  • 17655-0 – Genslew for Proposal 10599 – Slot#13 @053/1717z
  • 17656-0 – Genslew for Proposal 10599 – Slot#12 @053/1718z
  • 17658-0 – Genslew for Proposal 10599 – Slot#1 @053/1834z


                        SCHEDULED      SUCCESSFUL
FGS GSacq               04                    04
FGS REacq               09                    09
OBAD with Maneuver  12                    12


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