Status Report

NASA Hubble Space Telescope Daily Status Report #4178

By SpaceRef Editor
August 17, 2006
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NASA Hubble Space Telescope Daily Status Report #4178

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT August 15, 2006 (DOY 227)


ACS/HRC 10909

Exploring the diversity of cosmic explosions: The supernovae of gamma-ray bursts

While the connection between gamma-ray bursts {GRBs} and supernovae {SNe} is now clearly established, there is a large variety of observational properties among these SNe and the physical parameters of these explosions are poorly known. As part of a comprehensive program, we propose to use HST in order to obtain basic information about the supernovae associated with gamma-ray bursts. HST offers the means to cleanly separate the light curves of the GRB afterglow from the supernova, and to remove the contamination from the host galaxy, opening a clear route to the fundamental parameters of the SN. From these observations, we will determine the absolute magnitude at maximum, the shape of the spectral energy distribution, and any change over time of the energy distribution. We will also measure the rate of decay of the exponential tail. Merged with the ground-based data that we will obtain for each event, we will be able to compare our data set to models and constrain the energy of the explosion, the mass of the ejecta and the mass of Nickel synthesized during the explosion. These results will shed light on the apparent variety of supernovae associated with gamma-ray bursts and X-ray flashes, and on the relation between these SNe and other, more common varieties of core- collapse explosions.

ACS/SBC 10184

A New Class of Bright Ultraviolet Variable Sources in the Globular Cluster NGC 1851

Our reductions of archival STIS/FUV-MAMA data {AR9225} have discovered 13 completely unexpected and unexplained Ultraviolet bright variables. Eleven of the variables have been identified with evolved stars {Horizontal Branch or Asymptotic Giant Branch}. The total number and nature of these systems is completely unknown. If these variables are binaries the implication is that the binary fraction {up to 25%} in NGC 1851 is the highest in all Galactic globular clusters. The radial distributions of the variables and the blue horizontal branch stars imply a common origin and perhaps an explanation of the bi-modal morphology of the horizontal branch in the color magnitude diagrams of globular clusters. These variables may be the tip of the iceberg and a critical clue concerning the infamous “second parameter”. We propose to observe NGC 1851 on three occasions with the same setup as the archival data to determine the total number and periods of the ultraviolet variables.

ACS/WFC 10816

The Formation History of Andromeda’s Extended Metal-Poor Halo

We propose deep ACS imaging in the outer spheroid of the Andromeda galaxy, in order to measure the star formation history of its true halo. For the past 20 years, nearly all studies of the Andromeda “halo” were focused on the spheroid within 30 kpc of the galaxy’s center, a region now known to host significant substructure and populations with high metallicity and intermediate ages. However, two groups have recently discovered an extended metal-poor halo beyond 30 kpc; this population is distinct in its surface-brightness profile, abundance distribution, and kinematics. In earlier cycles, we obtained deep images of the inner spheroid {11 kpc on the minor axis}, outer disk {25 kpc on the major axis}, and giant tidal stream, yielding the complete star formation history in each field. We now propose deep ACS imaging of 4 fields bracketing this 30 kpc transition point in the spheroid, so that the inner spheroid and the extended halo populations can be disentangled, enabling a reconstruction of the star formation history in the halo. A wide age distribution in the halo, as found in the inner spheroid, would imply the halo was assembled through ongoing accretion of satellite galaxies, while a uniformly old population would be a strong indication that the halo was formed during the early rapid collapse of the Andromeda proto-galaxy.

ACS/WFC 10881

The Ultimate Gravitational Lensing Survey of Cluster Mass and Substructure

We propose a systematic and detailed investigation of the mass, substructure, and thermodynamics of one hundred X-ray luminous galaxy clusters at 0.15 < z < 0.3. The primary goal is to test our recent suggestion that this population is dominated by dynamically immature disturbed clusters, and that the observed mass-temperature relation suffers strong structural segregation. If confirmed, this would represent a paradigm shift in our observational understanding of clusters, that were hitherto believed to be dominated by mature, undisturbed systems. The key observation to this endeavor is Hubble imaging of cluster cores to identify robustly tangential and radial multiple arcs and measure the shape of faint galaxies. These strong and weak lensing signals will give an accurate measure of the total mass and structure of the dark matter distribution that we will subsequently compare with X-ray and Sunyaev Zeldovich Effect observables. The broader applications of our project include 1} the calibration of mass-temperature and mass-SZE scaling relations which will be critical for the calibration of proposed dark energy experiments, and 2} the low redshift baseline study of the demographics of massive clusters to aid interpretation of future high redshift {z>1} cluster samples. For this ultimate cluster survey, we request ACS SNAPSHOTS through the F606W filter drawn from a target list of 143 clusters.

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.

WFPC2 10745


This calibration proposal is the Cycle 14 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.


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

HSTARS: (None)



                         SCHEDULED      SUCCESSFUL 
FGS GSacq               08                    08 
FGS REacq               07                     07 
OBAD with Maneuver  30                    30 


BB SPA Back On-Line Flash Report

As the battery temperatures have decreased to acceptable levels, per plan the -BB SPA trim relay was successfully placed back on-line in hardware and FSW. The commanding was executed at approximately DOY 2006/227 15:17 GMT via Ops Request 17892. EPS SE monitored the system for one orbit and observed nominal battery temperatures cycling below 2 deg C. In addition, the SA section 1 & 5 anomaly is still present with the same signature of ~1.8 amps reduction in SA section 1 current and an increase of ~1.8 amps in SA section 5 current when battery 5 reaches cut-off.

SpaceRef staff editor.