[vsnet-alert 739] ALEXIS Observations of U Gem - EUV Turn On

[Jeff Bloch <jbloch@nis.lanl.gov>]

The ALEXIS Satellite has had complete coverage of the current outburst of 
U Gem in telescopes 2A (130 Angstrom Bandpass) and 2B (186 Angstrom 
Bandpass). The source has been detected in our 2A (130 Angstrom Bandpass) 
telescope, and strong EUV emission began on 02/19/97 sometime between 
00:00:00 UT and 01:00:00 UT, approximately one day after the visual 
magnitude rise. Flux has so far only been detected in our 2A telescope, 
at a count rate consistent with previous ALEXIS observations of U Gem 
outbursts.

Visit our web site and register to get a first hand look at the data on 
this and other bright EUV sources. 
(http://nis-www.lanl.gov/nis-projects/alexis)

To those VSNET readers, the ALEXIS alert mentioned and described at
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/ALEXIS/ugem9701.html bears some
further explaination. This marginal constrained search detection of U Gem 
in January by ALEXIS upon further examination was most likely a statistical
artifact, and upon detailed examination did not appear to be real. Daily
processing of ALEXIS data produces 36 maps of the sky per day (6 telescopes x
two telemetry dumps per day x 3 time exposure period maps (the previous 12,
24 and 48 hours)) so there are a lot of "typing monkeys" (i.e.  separate
trials or dice throws) and occasionally a line of Hamlet will appear by
random chance.

						Cheers,
						Jeff


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Jeffrey Bloch					Office:    (505) 665-2568
Astrophysics and Radiation Measurements Group	ALEXIS SOC:(505) 665-5975
Los Alamos National Laboratory			FAX:	   (505) 665-4414
Group NIS-2, Mail Stop D436		e-mail:    jbloch@lanl.gov
Los Alamos, NM 87545		 Digital Pager:	   (505)665-9800 #104-8074
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