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				TeL 617-354-0484	FAX 617-354-0665

			AAVSO ALERT NOTICE 197 (January 27,1995)


The NASA satellite Astro-2 is scheduled to be launched from the space shuttle on March 1, 
1995. We have been invited to participate in this mission and play a key role in its success. 
Astro-2 is a follow up to Astro-1, which was launched from the space shuttle in December 
of 1990, and to which we made significant contributions in the observations of cataclysmic 

The Hopkins Ultraviolet Telescope. (HUT), part of Astro-2, will be observing cataclysmic 
variables both in outburst and in quiescence during the mission, and for the first time, three 
other satellites - Extreme Ultraviolet Explorer (EUVE), Voyager, and the Japanese ASCA 
- will be observing these stars simultaneously with Astro-2 during these times. Thus, this 
will be the first time that cataclysmic variables will be observed simultaneously from x-ray 
through extreme ultraviolet and far ultraviolet to ultraviolet wavelengths.

The instruments aboard the satellites are ideal for studying the structure and evolution of 
the disk and winds in dwarf novae through outburst, the boundary layer in cataclysmic 
variables, and the temperature, size, and accretion column of the white dwarf component 
of magnetic cataclysmic variables like AM Her.

We have been asked to monitor closely the stars chosen for this mission and listed below, 
and to inform the astronomers involved as soon as any of these stars go into outburst.

0058+40 RX And	0409-71	VW Hyi	1247-28	EX Hya
0139+37 AR And	0749+22 U Gem	1813+49 AM Her
0207-63	WX Hyi	0804+28 YZ Cnc	1934+30 EM Cyg
0219+27 RW Tri	0814+73 Z Cam	2138+43 SS Cyg 
0309-22	EF Eri

The highest priority targets are VW Hyi, WX Hyi, and YZ Cnc, although the others may 
also be observed. We have been in communication with the astronomers involved with this 
mission for the past several months, and we have provided extensive observations for use in 
mission simulations.

We will be giving the astronomers an update on the behavior of these stars on February 21. 
Please monitor these stars closely from February 13 to March 17, and call in your 
observations, using the charge-free number (800-642-3883) at AAVSO Headquarters, or 
send email to Early observations are needed for the updates, and 
particularly after the satellite is launched on the shuttle on March 1. The day-to-day 
observations of these stars will be crucial to schedule the observations with Astro-2 and the 
other satellites. We will be in close communication with the astronomers from mid-
February to the end of the mission.

If you need charts for any of the stars below, please let us know, and we will send them to
you at no charge.

You, our observers, played a major role during the Astro-1 mission in the observations 
during the outburst of Z Cam. Through your early alerts and close monitoring, a very 
interesting set of observations was obtained on this star, in that astronomers detected 
forbidden oxygen VI lines that indicated a much hotter disk (see AAVSO Newsletter 8, July 
1991). Your contribution to the forthcoming Astro-2 mission is even more important and is 
truly vital! Astro-2, EUVE, Voyager, and ASCA will be pointed to observe the stars that 
YOU inform us are in outburst or in quiescence, so your contribution is absolutely crucial, 
and your timely communications are anxiously awaited.


Please continue to monitor U Gem closely, and call in or email your observations to 
AAVSO Headquarters when it goes into outburst, so that observations can be scheduled 
with the Hubble Space Telescope for the quiescent period following the outburst.

The answering machine at AAVSO Headquarters is on during nights and weekends for 
your convenience.

Many thanks for your observations and vital astronomical contributions to variable star 

Good observing!

Janet A. Mattei 

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484