Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “X-ray prisms”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

20 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Chandra Analysis with "CIAO"

CIAO (Chandra Interactive Analysis of Observations) is the name for the suite of tools and applications developed at the CXC for the analysis of data from the Chandra X-Ray Observatory and other missions. We describe some of the uses of CIAO for the analysis of Chandra (and other) data. There are several innovative aspects of CIAO. The user has the choice of a command line or a graphic-oriented approach. the use of the CXC "Data Model" results in: file-format independence: users have the ability of reading and writing files in FITS, QPOE, and IMH format raw and column filtering and binning can be applied to input file for *all* CIAO tools and applications avoiding the need to generate subsidiary data files on disk all filters are recorded in the "data subspace" of output files which is then recognized in the subsequent analysis. CIAO, in its current release, includes several tools both instrument specific (for ACIS, HRC and grating analysis) and for generic data analysis (data manipulation, source detection, transforms & convolutions, response, and timing) and several applications (Prism, Chips, and Sherpa plus Firstlook, ToolAgent and Filter Window in beta version) .

Elvis, Martin↗
NASA NTRS1993

Star counts from the Hubble Space Telescope Snapshot Survey. I - Galactic models

We report a photometric study of stars from 450 fields at high Galactic latitudes that were observed in the Hubble Space Telescope Snapshot Survey to an average limiting apparent magnitude of V = 21.4. There are 166 fields that contain quasars selected in radio, X-ray, and color-excess surveys. This sample of 273 stars is free of selection bias with respect to the density of stars. To within the Poisson errors, the total counts and magnitude distribution of this unbiased sample are in agreement with the Bahcall-Soneira model (Bahcall, 1986). The angular distribution of the faint stars favors, at the 2 sigma level, a somewhat steeper disk luminosity function and a smaller spheroid main-sequence normalization than given by the model. The sample does not have enough statistical power to distinguish between the two-component Bahcall-Soneira model and the three-component model first proposed by Gilmore and Reid (1983), which contains a thick disk. The statistical power of the survey would increase about 15-fold if colors were obtained for the stars: the data probe the main sequences of the disk, thick disk, and spheroid. Models with and without a thick disk could then be distinguished at the 6 sigma level. The HST Snapshot Survey includes an additional 284 fields, 279 of which are centered on quasars that were selected by objective-prism surveys. These 279 fields are expected to show and do exhibit bias against bright stars, making them unsuitable for testing Galactic models.

Gould, A.↗