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Session 44 - Stellar X-Ray Sources.
Display session, Tuesday, January 14
Metropolitan Ballroom,

[44.13] ALEXIS Observations of Flaring Activity on Late Type Stars

S. L. Cully (Space Sciences Lab.), R. A. Stern (Lockheed Palo Alto Research Lab.), J. J. Bloch (LANL), T. Rodriguez-Bell, O. H. W. Siegmund (Space Sciences Lab./ UC Berkeley)

The ALEXIS (Array of Low Energy X-ray Imaging Sensors) satellite is an EUV monitoring experiment consisting of six compact, normal incidence multilayer telescopes operating in narrow bands centered on 130, 172 and 186 A. The ALEXIS spacecraft, experiment and ground station are funded by DOE/OAC and have been built by a collaboration of Los Alamos and Sandia National Laboratories and the Space Sciences Laboratory at UC Berkeley. The six ALEXIS telescopes are arranged in pairs that cover overlapping 33 degree fields of view allowing ALEXIS to monitor approximately half the sky during each 100 second spin of the satellite with a spherical abberation resolution of approximately 0.5 degrees. The ALEXIS satellite was launched by a Pegasus booster into orbit on April 25, 1993. Due to damage sustained at the time of the launch , ground controllers did not make contact with the satellite until late June, 1993. By late July, full satellite operations had been restored through the implimentation of new procedures for attitude control. The satellite's wide field of view and narrow EUV bands centered on strong high temperature Fe line such as Fe XX/XXIII A, Fe XXIV 192 A and Fe XII 171 A make ALEXIS an ideal instrument to study flare statistics and to search for large infrequent flares on late type stars. We present composite EUV flare frequency distributions for a sample of 224 late type stars derived from over two years worth of ALEXIS data taken between January 29, 1994 and March 6, 1996.

Program listing for Tuesday