Status Report

NASA Hubble Space Telescope Daily Report #4430

By SpaceRef Editor
August 22, 2007
Filed under , ,
NASA Hubble Space Telescope Daily Report #4430

Notice: Due to the conversion of some ACS WFC or HRC observations into WFPC2, or NICMOS observations after the loss of ACS CCD science capability in January, there may be an occasional discrepancy between a proposal’s listed (and correct) instrument usage and the abstract that follows it.


– Continuing to collect World Class Science

PERIOD COVERED: UT August 20, 2007 (DOY 232)


WFPC2 10787

Modes of Star Formation and Nuclear Activity in an Early Universe Laboratory

Nearby compact galaxy groups are uniquely suited to exploring the mechanisms of star formation amid repeated and ongoing gravitational encounters, conditions similar to those of the high redshift universe. These dense groups host a variety of modes of star formation, and they enable fresh insights into the role of gas in galaxy evolution. With Spitzer mid-IR observations in hand, we have begun to obtain high quality, multi-wavelength data for a well- defined sample of 12 nearby {<4500km/s} compact groups covering the full range of evolutionary stages. Here we propose to obtain sensitive BVI images with the ACS/WFC, deep enough to reach the turnover of the globular cluster luminosity function, and WFPC2 U-band and ACS H-alpha images of Spitzer-identified regions hosting the most recent star formation. In total, we expect to detect over 1000 young star clusters forming inside and outside galaxies, more than 4000 old globular clusters in >40 giant galaxies {including 16 early-type galaxies}, over 20 tidal features, approximately 15 AGNs, and intragroup gas in most of the 12 groups. Combining the proposed ACS images with Chandra observations, UV GALEX observations, ground-based H-alpha imaging, and HI data, we will conduct a detailed study of stellar nurseries, dust, gas kinematics, and AGN.

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 DARKs. 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 11219

Active Galactic Nuclei in nearby galaxies: a new view of the origin of the radio-loud radio- quiet dichotomy?

Using archival HST and Chandra observations of 34 nearby early-type galaxies {drawn from a complete radio selected sample} we have found evidence that the radio-loud/radio-quiet dichotomy is directly connected to the structure of the inner regions of their host galaxies in the following sense: [1] Radio-loud AGN are associated with galaxies with shallow cores in their light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep cusps. Since the brightness profile is determined by the galaxy’s evolution, through its merger history, our results suggest that the same process sets the AGN flavour. This provides us with a novel tool to explore the co-evolution of galaxies and supermassive black holes, and it opens a new path to understand the origin of the radio-loud/radio-quiet AGN dichotomy. Currently our analysis is statistically incomplete as the brightness profile is not available for 82 of the 116 targets. Most galaxies were not observed with HST, while in some cases the study is obstructed by the presence of dust features. We here propose to perform an infrared NICMOS snapshot survey of these 82 galaxies. This will enable us to i} test the reality of the dichotomic behaviour in a substantially larger sample; ii} extend the comparison between radio-loud and radio-quiet AGN to a larger range of luminosities.

NIC2 11329

The Final SHOE; Completing a Rich Cepheid Field in NGC 1309

The Cycle 15 SHOES program {GO 10802} is a large HST program allocated 186 orbits to rebuild the distance ladder using NGC 4258 as a new anchor, a set of 6 recent, ideal type Ia supernovae and Cepheids in their hosts, and NICMOS as a single, homogeneous photometer of long period Cepheids. These tools provide the means to achieve a 4% measurement of the Hubble constant, an invaluable constraint for cosmic concordance fits to dark energy models. Unfortunately, the SHOES NICMOS integrations of long period Cepheids in the last and most recent nearby type Ia supernova host, NGC 1309, are too short because the preliminary estimate of its distance, 30 Mpc, was too low. Our refined estimate now based on the full reduction of both our Cycle 14 and 15 ACS data is 36 Mpc, or 0.4 mag farther. Fortunately, Nature was extremely kind providing a single rich NIC2 field in which we can fully make up for the shortfall due to its abundance of Cepheids. We are expensing our final 4 orbits on this field of a dozen P>30 day Cepheids and seek an additional 5 orbits to reach the depth for measuring the mean F160W magnitudes of the long-period Cepheids with the necessary signal-to-noise ratios of better than 10.

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 11031

CTE Background Dependence 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 {charge 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 CTE over the last 13 years permits an assessment of all but the last condition. The dependence of CTE on background signal must be characterized, however, because a large fraction of WFPC2 images have been obtained under conditions of significant sky background. This program aims to assess the end-of-life CTE of WFPC2’s CCDs separately as a function of background signal. Traditional images of an off-center field in NGC 5139 {Omega Cen} are recorded after preflashing {or before postflashing} the CCDs with internal lamps to provide average background signals of 0-160 e-, which span the range of sky backgrounds observed in ~99% of long-exposure narrow- and broad-band WFPC2 images.

WFPC2 11234

A Brief Revisit of the Crab

We propose using WFPC2 to obtain continuum-dominated images of the Crab pulsar and environs closely duplicating archival exposures from 1994 and 1995. By matching the archival data we can realize ~3mas precision astrometry with a minimum of systematic effects over a maximum {~13.5y} baseline. This determines the Crab proper motion to better than 0.3mas/yr {3km/s} accuracy and measures its position angle to better than 1.5degrees, i.e. reducing the errors of the best present {HST archive} measurement by a factor of three. Most importantly, this provide a nearly systematic-free result. This proper motion measurement would match the precision of the CXO-measured angular momentum vector. Comparison of these vectors is the foundation of an effort to understand the physical origin of the large momentum kick at pulsar birth.

WFPC2 11289

SL2S: The Strong Lensing Legacy Survey

Recent systematic surveys of strong galaxy-galaxy lenses {CLASS, SLACS, GOODS, etc.} are producing spectacular results for galaxy masses roughly below a transition mass M~10^13 Mo. The observed lens properties and their evolution up to z~0.2, consistent with numerical simulations, can be described by isothermal elliptical potentials. In contrast, modeling of giant arcs in X-ray luminous clusters {halo masses M >~10^13 Mo} favors NFW mass profiles, suggesting that dark matter halos are not significantly affected by baryon cooling. Until recently, lensing surveys were neither deep nor extended enough to probe the intermediate mass density regime, which is fundamental for understanding the assembly of structures. The CFHT Legacy Survey now covers 125 square degrees, and thus offers a large reservoir of strong lenses probing a large range of mass densities up to z~1. We have extracted a list of 150 strong lenses using the most recent CFHTLS data release via automated procedures. Following our first SNAPSHOT proposal in cycle 15, we propose to continue the Hubble follow-up targeting a larger list of 130 lensing candidates. These are intermediate mass range candidates {between galaxies and clusters} that are selected in the redshift range of 0.2-1 with no a priori X-ray selection. The HST resolution is necessary for confirming the lensing candidates, accurate modeling of the lenses, and probing the total mass concentration in galaxy groups up to z~1 with the largest unbiased sample available to date.


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

HSTARS: (None)



                       SCHEDULED      SUCCESSFUL 
FGS GSacq               06                 06 
FGS REacq               08                 08 
OBAD with Maneuver 28                 28 


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