Status Report

NASA Hubble Space Telescope Daily Status Report #4391

By SpaceRef Editor
June 27, 2007
Filed under , ,
NASA Hubble Space Telescope Daily Status Report #4391

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 25, 2007 (DOY 176)


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.

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 11133

Late-Time Photometry of SN 2005hk: A New Kind of Type Ia Supernova

Our lack of understanding of Type Ia supernova {SN Ia} explosions limits our confidence in their use for cosmology. While there is broad agreement that these objects represent the explosions of white dwarfs, the details of the explosion mechanism are not well- understood. Recent observations have detected a previously unacknowledged variant class of SNe Ia whose photometric and spectroscopic peculiarities make them quite distinct from normal SNe Ia. These objects represent a challenge for thermonuclear supernova models, as a complete theory of exploding white dwarfs must allow for their existence. A particularly well-studied example of this class of objects is the recent SN 2005hk, whose properties in some respects resemble those of models which invoke a subsonic burning front, called a deflagration. We propose to test SN Ia models by obtaining late-time photometry for this extreme SN Ia using WFPC2 and NICMOS on HST. We will accurately measure the late-time photometric decline rate and spectral energy distribution {SED}. These observations will allow us to test whether the ejecta contain the large amount of oxygen predicted by certain models, the efficiency of energy deposition by gamma rays and positrons, and possibly detect major evolution of the SED expected due to a change in the dominant cooling mechanism of the ejecta.

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.

WFPC2 11112

The Collisional Ring Galaxy NGC922

We request WFPC2 images of the newly recognized collisional ring galaxy NGC922 which will become the nearest such system observed by HST. These will be used to get a clear understanding of the geometry of the interaction and the induced star formation in this system. Quantitive modeling of the colors of the star clusters and stellar populations will be used to constrain the star formation history of the system. They will also be used to test the “infant mortality” scenario for star cluster evolution. The derived population ages will test predictions of how star formation evolves in the various components {ring, core, spokes} of collisional rings, and will improve our own simulations of this system. These will be used to determine the final fate of the stars formed in the present burst – some will end up in a central bar or bulge while others will become part of a thickened disk. By analogy this will tell us how similar collisions enrich stellar populations in the early universe. This is especially relevant since the number density of collisional rings increases rapidly with redshift.

WFPC2 11140

Can mass-ejections from late He-shell flash stars constrain convective/reactive flow modeling of stellar interiors?

The existence of H-deficient knots around the central stars of the planetary nebulae Abell 30 and Abell 78 is still unexplained. We hypothesize that these knots were ejected during a very late helium-shell flash {= very late thermal pulse, VLTP} suffered by the precursor white dwarf stars. If this is true, then the characteristics of these knots {mass, velocity, density, spatial distribution} allow to draw conclusions on the course of the hydrogen- ingestion flash detonation that is triggered by the He-shell flash. This provides important, otherwise inaccessible constraints for the hydrodynamical modeling of convective/reactive flows in stellar interiors. Understanding the physics of these flows is not only important for the understanding of these particular central stars, but also for the frequent, very similar convective/reactive events that determine the nucleosynthesis in Pop. III stars. With this proposal we want to proof or discard the idea that the H-deficient knots are resulting from a VLTP. If true, then they can be exploited for flash-physics diagnostics. We propose a simple test. We search for such knots around five H-deficient central stars {PG1159 stars}. Our models predict, that only those stars with residual nitrogen in the atmosphere have suffered a VLTP and, hence, should have expelled knots. We therefore want to take [O III] images of stars which have photospheric N and those which do not.


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


10870 – GSAcq(1,2,1) failed to RGA Hold (Gyro Control)

Upon acquisition of signal at 177/06:04:01, the GSAcq(1,2,1) scheduled at 177/05:34:41 – 05:42:46 had failed to RGA Hold due to (QF1STOPF) stop flag indication on FGS-1. Pre-acquisition OBADs (RSS) attitude correction values not available pending future Engineering Tape Recorder (ETR) Dump. Post-acq OBAd/MAP had (RSS) value of 1258.80 arcseconds.


                               SCHEDULED      SUCCESSFUL 

FGS GSacq                       5                     4 
FGS REacq                       7                     7 
OBAD with Maneuver              22                    22 



SpaceRef staff editor.