NASA Hubble Space Telescope Daily Report # 3659

Status Report From: Space Telescope Science Institute
Posted: Thursday, July 22, 2004

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science




ACS/HRC 10255

A Never Before Explored Phase Space: Resolving Close White Dwarf / Red Dwarf Binaries

We propose an ACS Snapshot imaging survey to resolve a well-defined sample of highly probable white dwarf plus red dwarf close binaries. These candidates were selected from a search for white dwarfs with infrared excess from the 2MASS database. They represent unresolved systems {separations less than approximately 2" in the 2MASS images} and are distributed over the whole sky. Our HST+ACS observations will be sensitive to a separation range {1-20 AU} never before probed by any means. The proposed study will be the first empirical test of binary star parameters in the post-AGB phase, and cannot be accomplished from the ground. By resolving as few as 20 of our ~100 targets with HST, we will be able to characterize the distribution of orbital semi-major axes and secondary star masses.


CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS.


Tracing the History of Cosmic Expansion to z~2 with Type Ia Supernovae

Type Ia supernovae {SNe Ia} provide the only direct evidence for an accelerating universe, an extraordinary result that needs the most rigorous test. The case for cosmic acceleration rests on the observation that SNe Ia at z = 0.5 are about 0.25 mag fainter than they would be in a universe without acceleration. A powerful and straightforward way to assess the reliability of the SN Ia measurement and the conceptual framework of its interpretation is to look for cosmic deceleration at z > 1. This would be a clear signature of a mixed dark-matter and dark-energy universe. Systematic errors in the SNe Ia result attributed to grey dust or cosmic evolution of the SN Ia peak luminosity would not show this change of sign. We have obtained a toehold on this putative ``epoch of deceleration'' with SN 1997ff at z = 1.7, and 3 more at z > 1 from our Cycle 11 program, all found and followed by HST. However, this is too important a test to rest on just a few objects, anyone of which could be subject to a lensed line-of-sight or misidentification. Here we propose to extend our measurement with observations of twelve SNe Ia in the range 1.0 < z < 1.5 or 6 such SNe Ia and 1 ultradistant SN Ia at z = 2, that will be discovered as a byproduct from proposed Treasury and DD programs. These objects will provide a much firmer foundation for a conclusion that touches on important questions of fundamental physics.

ACS/WFC 10188

In-Depth Study of The Antennae with NICMOS and ACS

We propose new observations of "The Antennae" {NGC 4038/39}, the nearest and youngest example of a major disk-disk merger, with NICMOS and ACS. The long overdue NICMOS observations will allow us to penetrate the dust in the Overlap Region, measure the P_alpha emission and CO band strengths of young clusters, and study supernova remnants in heavily obscured regions using [FeII] images. The high resolution {0.05" pixel} ACS observations will allow us for the first time to reliably distinguish clusters from stars based on their apparent sizes, and to potentially identify hundreds of supernova remnants that may control the energy balance and feedback mechanisms within the ISM {based on [SII] images}. In conjunction with our previous WFPC2, GHRS, and STIS observations, the new data will provide answers to fundamental questions such as: How do these clusters form and evolve? How quickly are they destroyed and what fraction of the field stars were formed in clusters. How many clusters are hidden by dust? How do the clusters and associated supernovae affect the local and global ISM? What are the dynamical masses of the clusters, and are the stellar IMF's truncated? Simultaneous parallel observations will also determine whether clusters can form in the more quiescent environment of the inner tails. A better understanding of how mergers form tremendous numbers of clusters and stars in the local universe will help shed light on processes that are crucial during galaxy assembly throughout the observable universe.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

STIS/CCD 10018

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 10020

CCD Bias Monitor - Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.

STIS/CCD 10023

STIS CCD Spectroscopic Flats C12

Obtain CCD flats on the STIS CCD in spectroscopic mode

STIS/CCD 10222

The Next Generation Spectral Library

We propose to complete our snapshot program to produce a Next Generation Spectral Library of 600 stars for use in modeling the integrated light of galaxies and clusters. This program is using the low dispersion UV and optical gratings of STIS. The library will be roughly equally divided among four metallicities, very low {[Fe/H] < -1.5}, low {-1.5 < [Fe/H] < -0.5}, near-solar {-0.3 < [Fe/H] < 0.1}, and super-solar {[Fe/H] > 0.2}, well-sampling the entire HR-diagram in each bin. Such a library will surpass all extant compilations and have lasting archival value, well into the Next Generation Space Telescope era. Because of the universal utility and community-broad nature of this venture, we waive the entire proprietary period.


UV extinction by dust in unexplored LMC environments

The ensemble of results from studies of the UV extinction in the Milky Way, Magellanic Clouds {MC}, M31 and M33, indicates a complex dependence of the dust properties with environment, where starburst activity and metallicity are relevant factors. Work in the LMC to date, based on IUE data, has several drawbacks: a} only supergiants could be used, b} they all have moderate extinction, c} the IUE S/N is limited, d} the large IUE slit may include light from other sources, such as scattered light from dust or faint companion stars, e} studies are confined to few {extreme} environments. We propose to obtain UV extinction curves more accurate than previous ones {from STIS spectra of main sequence stars with higher reddening}, sampling four environments in the LMC with different levels of star formation activity, including the general field, hitherto unexplored. The results will characterize the properties of dust in different conditions, at the LMC metallicity, which is useful to interpret integrated properties of distant galaxies, as well as GALEX upcoming UV surveys. A complementary study is under way with FUSE in the far-UV range. The combined results will provide insight on the properties of small grains.

WFPC2 10071

WFPC2 CYCLE 12 Supplemental Darks Part 3/3

This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels.


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

HSTAR 9486 - GSAcq(1,3,1) suffers Loss of Lock - recovery successful.While review PTAS TC log from SB194O SMS processing, OTA SE determined that this GSAcq(1,3,1), beginning at 2004.195/16:33:37, successfully acquired FL-DV on both guide stars with Take Data flag ON at 16:39:31. But, the Take Data flag went down within 4 seconds, the FGSs returned to SSM control and the guide stars were acquired again, with the Take Data flag ON at 16:41:24. No further Loss of Lock instance was noted prior to the 17:06:07 PCPSAA. Under investigation.

HSTAR 9487 - GSAcq (3,2,3) returned to SSM control - ultimately successful.OTA SE review of trending data revealed that FGS-2 returned to SSM after entering Course Mode. The second attempt to enter course mode resulted in a successful transition to Fine Lock and ultimately successful acquisition. Under investigation.


1115-0 CCC IPCONFIG Connections @ 203/12:41z

                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq               11                         11
FGS REacq                08                         08
FHST Update            15                         15


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