Status Report

NASA Hubble Space Telescope Daily Report #3993

By SpaceRef Editor
November 22, 2005
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NASA Hubble Space Telescope Daily Report #3993

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT November 21, 2005 (DOY 325)


ACS/HRC 10396

Star Clusters, Stellar Populations, and the Evolution of the Small Magellanic Cloud

As the closest star forming dwarf galaxy, the SMC is the preferred location for detailed studies of this extremely common class of objects. We therefore propose to use the capabilities of ACS, which provide an improvement by an order of magnitude over what is possible with ground- based optical imaging surveys that are limited by confusion anddepth, to measure key stellar population parameters in the SMC from VI color-magnitude diagrams. Our program focuses on regions where crowding makes HST essential and includes 7 star clusters and 7 field star locations. We will measure accurate ages of the clusters, test stellar evolution models, gain fiducial stellar sequences to use in fitting the field stars, check the form of the IMF, and substantially extend the study of RR Lyrae variables in the key NGC121 SMC globular cluster. The field pointings will allow us to reconstruct the star formation history, look for enhanced star formation that is expected when the SMC interacts with the LMC and/or Milky Way, and compare its main sequence luminosity {and mass} functions with those of the Milky Way, LMC, and UMi dwarf spheroidal. This proposal is part of a coordinated HST and ground-based study of the stellar history and star formation processes in the SMC.

ACS/HRC 10549

SAINTS – Supernova 1987A INTensive Survey

SAINTS is a program to observe SN 1987A, the brightest supernova in 384 years, as it morphs into the youngest supernova remnant at age 18. HST is the unique and perfect tool for spatially- resolved observations of the many physical components of SN 1987A. A violent encounter is underway between the fastest-moving debris and the circumstellar ring, exciting hotspots seen with HST that are suddenly lighting up. The optical and X-ray flux from the ring are both rising rapidly: HST and Chandra observations taken together are needed to understand the physics of these shocked regions. In Cycle14, the hotspots may fuse as the shock fully enters the ring. Photons from these shocks may excite previously hidden gas outside the ring, revealing the true extent of the mass loss that preceded the explosion. The inner debris of the explosion itself, still excited by radioactive isotopes produced in the explosion, is now well resolved by ACS and seen to be aspherical, providing direct clues to the mechanism of the explosion. Our search for a compact remnant is beginning to eliminate some theoretical possibilities and we have the opportunity in Cycle 14 to place much more stringent limits with NICMOS. Many questions about SN 1987A remain unanswered. How did the enigmatic three rings form in the late stages of Sanduleak -69 202? Precisely what took place in the center during the core collapse and bounce? Is a black hole or a neutron star left behind in the debris? SAINTS has been a continuous program since HST was launched– we propose to extend this rich and deep data set for present use and future reference to answer these central questions in the science of supernovae.


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 10135

Unveiling the Progenitors and Physics of Cosmic Explosions

GRBs and XRFs are clearly highly asymmetric explosions and require a long-lived power source {central engine}. In contrast, nearby core-collapse events are essentially spherical explosions. However, the failure of spherical neutrino driven collapses has led to the idea that asymmetric energy release is essential for the explosion. The recent finding of a Type Ic SN in GRB 030329, the association of the low energy event GRB 980425 with SN 1998bw, the theoretical development discussed above and the rise of collapsar models make it timely to consider whether all these explosions contain engines. Given the uncertainties in theoretical modeling it is clear that observations are needed to guide models. A priori there is little reason to expect connection between the ultra-relativistic jet that powers the GRB and the explosive nucleosynthesis of the ~0.5 solar masses of Nickel-56 that powers the accompanying supernova. We propose a comprehensive program of ACS photometric searches {and measurements} for SNe associated with GRBs and XRFs. In concert, we will undertake ground- based spectroscopy to determine velocity widths, and measure engine parameters from pan- chromatic afterglow observations. Our goal is to produce a comprehensive database of engine and SN physical parameters against which theoretical modeling will be guided.

ACS/WFC 10587

Measuring the Mass Dependence of Early-Type Galaxy Structure

We propose two-color ACS-WFC Snapshot observations of a sample of 118 candidate early- type gravitational lens galaxies. Our lens-candidate sample is selected to yield {in combination with earlier results} an approximately uniform final distribution of 40 early-type strong lenses across a wide range of masses, with velocity dispersions {a dynamical proxy for mass} ranging from 125 to 300 km/s. The proposed program will deliver the first significant sample of low-mass gravitational lenses. All of our candidates have known lens and source redshifts from Sloan Digital Sky Survey data, and all are bright enough to permit detailed photometric and stellar- dynamical observation. We will constrain the luminous and dark-matter mass profiles of confirmed lenses using lensed-image geometry and lens-galaxy structural/photometric measurements from HST imaging in combination with dynamical measurements from spatially resolved ground-based follow-up spectroscopy. Hence we will determine, in unprecedented detail, the dependence of early-type galaxy mass structure and mass-to-light ratio upon galaxy mass. These results will allow us to directly test theoretical predictions for halo concentration and star-formation efficiency as a function of mass and for the existence of a cuspy inner dark- matter component, and will illuminate the structural explanation behind the fundamental plane of early-type galaxies. The lens-candidate selection and confirmation strategy that we propose has been proven successful for high-mass galaxies by our Cycle 13 Snapshot program {10174}. The program that we propose here will produce a complementary and unprecedented lens sample spanning a wide range of lens-galaxy masses.

NIC1/NIC2 10410

Anisotropy and obscuration in the near-nuclear regions of powerful radio galaxies

Despite the success of the orientation-based unified schemes for powerful radio sources, we are still far from understanding the distribution of obscuring material in the near-nuclear regions of such sources, and how this distribution evolves with radio power. Following on from our highly successful Cycle 7 pilot observations of Cygnus A, we propose a near-IR polarimetric survey of a complete sample of powerful radio galaxies in order map the near-nuclear illumination cones, and investigate the distribution of obscuring material on a 0.1 to 1kpc scale. In particular, the observations will allow us to test the “receding torus model” which predicts that the opening angles of the illumination cones are smaller in low redshift/low power radio galaxies than in their high redshift/high power counterparts.We will also investigate whether AGN- and jet-driven outflows have a substantial effect on distribution of obscuring material by “hollowing out” the quasar illumination cones in the more powerful sources. Finally, by using our polarization maps to search for signs of intrinsic anisotropy in the near-IR continuum within the cones, we will investigate the geometry of the near-IR continuum emitting regions close to the quasar nuclei. These observations are not only crucial for our understanding of radio source unification, but also provide key information about the effects of AGN-induced outflows on the ISM of the host galaxies.


NICMOS Post-SAA calibration – CR Persistence Part 2

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.

WFPC2 10748

WFPC2 CYCLE 14 Standard Darks

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)


17592-0 – Genslew for proposal 10539 – slot 14 @ 325/1952z

17593-0 – Genslew for proposal 10539 – slot 13 @ 325/1954z

17594-0 – Genslew for proposal 10539 – slot 12 @ 325/1955z


                         SCHEDULED      SUCCESSFUL
FGS GSacq               04                     04
FGS REacq               12                     12
OBAD with Maneuver  20                     20


SpaceRef staff editor.