NASA Hubble Space Telescope Daily Report # 3555

Status Report From: Space Telescope Science Institute
Posted: Friday, February 20, 2004

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science




ACS 9984

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground mass provide a powerful method of directly measuring the amount and distribution of dark matter. Several groups have recently detected this weak lensing by large-scale structure, also called cosmic shear. The high resolution and sensitivity of HST/ACS provide a unique opportunity to measure cosmic shear accurately on small scales. Using 260 parallel orbits in Sloan textiti {F775W} we will measure for the first time: beginlistosetlength sep0cm setlengthemsep0cm setlength opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the skewness of the shear distribution, and em the magnification effect. endlist Our measurements will determine the amplitude of the mass power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20, and the mass density Omega_m with s/n=4. They will be done at small angular scales where non-linear effects dominate the power spectrum, providing a test of the gravitational instability paradigm for structure formation. Measurements on these scales are not possible from the ground, because of the systematic effects induced by PSF smearing from seeing. Having many independent lines of sight reduces the uncertainty due to cosmic variance, making parallel observations ideal.

ACS/HRC 9853

A Search for Young Binary Brown Dwarfs: Constraining Formation Scenarios and Masses Through Multiplicity

We propose to use the Advanced Camera for Surveys / High Resolution Camera to conduct a direct imaging multiplicity survey of 34 young brown dwarfs in the nearest regions of recent star formation, the T association Taurus-Auriga and the OB association Upper Scorpius. The determined multiplicity fraction, the separation distribution, and the mass ratio distribution will offer stringent observational constraints on proposed brown dwarf formation scenarios. Moreover, the small semi-major axes of known field and open cluster brown dwarf binaries suggest the exciting possibility of our identifying several very close binaries {< 15 AU}. Continued monitoring of these systems would yield, on a decade timescale, the first dynamical mass estimates of T Tauri brown dwarfs. With masses intermediate between those of stars and planets, brown dwarfs offer our best hope of relating the reasonably well understood processes of star formation to the less well understood processes of planet formation.


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.

ACS/WFC 9575

Default {Archival} Pure Parallel Program.

The Advanced Camera for Surveys (WFC) was used to test ACS pure parallels in POMS.

ACS/WFC 9779

Giant Lya Halos Around High Redshift Radio Galaxies

We propose to use the ACS + ramp filter to image the morphologies of several high redshift, giant Lya emission line halos associated with radio galaxies. High redshift radio galaxies are the likely precursors of the most massive elliptical galaxies known today. There is increasing evidence that they are forming in the centers of giant halos in overdense galaxy regions or `protoclusters'. The halos provide a unique diagnostic to study the formation of these massive galaxies and determine the importance of AGN/starburst feedback during this process. The capability of HST to resolve fine detail is essential for the interpretation of their complex morphologies. Our targets have also a number of Lya excess galaxies near the halos which fall within the field-of-view of the ACS + ramp filters. Our images will resolve these systems and we will investigate whether there is morphological evidence for starburst outflows. Starburst winds have been proposed as a source of heat and chemical enrichment for protoclusters, which may significantly affect their evolution.

ACS/WFC 9902

The Evolution of the Host Galaxies of Radio-Quiet Quasars

Study of the host galaxies and environments of high redshift AGN is proving a valuable probe of current theories of how galaxies form and evolve. Results from our NICMOS imaging program have indicated that the hosts of z ~ 2 -- 3 faint radio-quiet quasars {RQQ} have luminosities only around local L*, making them similar to Lyman-break field galaxies at the same redshifts, and to the low-z hosts RQQ hosts. This is roughly consistent with theoretical predictions of Kauffmann & Haehnelt {2000} for the hierarchical buildup of galaxy hosts and their relation to their resident supermassive black holes. The luminosity of the AGN in these RQQ is key to understanding this relationship, however, and we are making a comprehensive archival HST imaging study of the hosts of RQQs from low to high z at a range of nuclear luminosities. At intermediate z, however, there are no studies of the hosts of RQQs in the faint luminosity range that represents the bulk of the quasar population. In the present proposal, we request imaging at the same rest-wavelengths as our high-z sample of the hosts of 10 similarly luminous RQQs at z ~ 0.9. These data will fill in an important part of the parameter space defined by quasar luminosity and redshift. Combined with existing HST data they will allow us to trace the evolution of the hosts of RQQ and that of the relationship between quasar luminosity and host galaxy luminosity.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

We propose to continue managing the NICMOS pure parallel program. Based on our experience, we are well prepared to make optimal use of the parallel opportunities. The improved sensitivity and efficiency of our observations will substantially increase the number of line-emitting galaxies detected. As our previous work has demonstrated, the most frequently detected line is Halpha at 0.7<z<1.9, which provides an excellent measure of current star formation rate. We will also detect star-forming and active galaxies in other redshift ranges using other emission lines. The grism observations will produce by far the best available Halpha luminosity functions over the crucial--but poorly observed--redshift range where galaxies appear to have assembled most of their stellar mass. This key process of galaxy evolution needs to be studied with IR data; we found that observations at shorter wavelengths appear to have missed a large fraction of the star-formation in galaxies, due to dust reddening. We will also obtain deep F110W and F160W images, to examine the space densities and morphologies of faint red galaxies. In addition to carrying out the public parallels, we will make the fully reduced and calibrated images and spectra available on-line, with some ground-based data for the deepest parallel fields included.


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.


The Origin of Gamma-Ray Bursts

The rapid and accurate localization of gamma-ray bursts {GRBs} promised by a working HETE-2 during the coming year may well revolutionize our ability to study these enigmatic, highly luminous transients. We propose a program of HST and Chandra observations to capitalize on this extraordinary opportunity. We will perform some of the most stringent tests yet of the standard model, in which GRBs represent collimated relativistic outflows from collapsing massive stars. NICMOS imaging and STIS CCD spectroscopy will detect broad atomic features of supernovae underlying GRB optical transients, at luminosities more than three times fainter than SN 1998bw. UV, optical, and X-ray spectroscopy will be used to study the local ISM around the GRB. Chandra spectroscopy will investigate whether the GRB X-ray lines are from metals freshly ripped from the stellar core by the GRB. HST and CTIO infra-red imaging of the GRBs and their hosts will be used to determine whether `dark' bursts are the product of unusually strong local extinction; imaging studies may for the first time locate the hosts of `short' GRBs. Our early polarimetry and late-time broadband imaging will further test physical models of the relativistic blast wave that produces the bright GRB afterglow, and will provide unique insight into the influence of the GRB environment on the afterglow.

STIS/CCD 10017

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD.

STIS/CCD 10019

CCD Bias Monitor - Part 1

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 10085

STIS Pure Parallel Imaging Program: Cycle 12

This is the default archival pure parallel program for STIS during cycle 12.

STIS/MA2 9804

Experimental Proof of the Neutrino Process in SN from Boron Isotope Measurements

The light elements Li, Be, and B are formed in the Big Bang {Li} and by Cosmic Ray {CR} spallation. But the abudance of 11B has never been satisfactorily explained: 11B/10B in the solar system is 4.0, CR spallation predicts 2.5. There needs to be another source of 11B. Woosely et al. {1990} predict the large flux of neutrinos in Type II supernovae will sythesize elements, including converting 12C to 11B. This "neutrino process" has never been experimentally verified. A "smoking gun" would be to find a metal poor star whose elements came primarily from Type II SN and whose B is pure 11B -- only the neutrino process could produce that. In a previous cycle we obtained STIS measurements of a metal poor star and were able to clearly show that 11B/10B <= 4. We now ask for additional observations of higher S/N, which can distinguish if 11B/10B = 4, or if the mix is pure 11B. In either case we will end up with a precise measure of how much 11B in old stars is NOT produced by CRs, and likely due to SN, and can place a new constraint on the temperature and density of SN models in the region where neutrino-induced nucleosynthesis is thought to take place. Although this test could be made in a single star, we ask to observe two, to increase the confidence in what is a subtle isotopic measurement. We propose to observe the brightest two suitable metal poor stars. One is in the CVZ.

WFPC2 10070

WFPC2 CYCLE 12 Supplemental Darks Part 2/3

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

WFPC2 10084

WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel program. The program will be used to take parallel images of random areas of the sky, following the recommendations of the 2002 Parallels Working Group.

WFPC2 10090

WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans.


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

HSTAR 9330: GS Acquisition (2,1,1) @ 051/00:48:24Z resulted in FL backup using FGS 2 due to SSLE on FGS 1. Prior FHST FM Updates @ 051/00:30:06Z and 00:32:51Z showed good attitude error vector. FHST Map @ 051/01:24:14Z showed 3-axis (RSS) vehicle error ~ 3.00 arcsec. Subsequent GS Re-acquisition (2,1,1) @ 051/02:24:56Z resulted in FL backup (2,0,2). Under investigation.


OPS NOTES EXECUTED: 1202-1 - Realtime Monitor of Earth Limb Pointing Equation @ 050/1750z

                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq               5                          5
FGS REacq               10                        10
FHST Update             14                        14


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