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| Paper: |
The ALEXIS data processing package: an IDL-based system |
| Volume: |
25, Astronomical Data Analysis Software and Systems I |
| Page: |
502 |
| Authors: |
Bloch, J. J.; Smith, B. W.; Edwards, B. C. |
| Abstract: |
The ALEXIS experiment is a mini-satellite containing six wide angle EUV/ultrasoft x ray telescopes. Its purpose is to map out the sky in three narrow (5 pct.) bandpasses around 66, 71, and 93 eV. The 66 and 71 eV bandpasses are centered on intense Fe emission lines which are characteristic of million-degree plasmas such as the one thought to produce the soft x ray background. The 93 eV bandpass is not near any strong emission lines and is more sensitive to continuum sources. The emission will be launched on the Pegasus Air-Launched Vehicle in the first quarter of 1992 into a 400-nautical-mile, high inclination orbit and will be controlled entirely from a small ground station located at Los Alamos. The six telescopes are arranged in three pairs. As the satellite spins twice a minute they scan the entire anti-solar hemisphere. Each f/1 telescope consists of a spherical, multilayer coated mirror with a curved, microchannel plate detector located at the prime focus. The multilayer coatings determine the bandpasses of the telescopes. The field of each telescope is 30 degrees with a spatial resolution of 0.5 degree, limited by spherical aberration. The data processing requirements for ALEXIS are large. Each event in one of the six telescopes is telemetered to the ground with its time of arrival and position on the detector. This information must be folded with the aspect solution for the satellite to reconstruct the direction on the sky from which the photon came. Because of the way the six telescopes scan the sky, the effective exposure calculations is also very compute-intensive. ALEXIS may generate up to 100 megabytes of raw data per day, which are converted into a gigabyte per day of processed data. The entire analysis system is built on a set of SPARC station platforms. |
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