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Alert Notice 197: Observations of cataclysmic variables for Astro-2, EUVE, Voyager, and ASCA satellites AND Reminder regarding outburst of 0749+22 U Gem

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THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
BITNET: aavso@cfa SPAN: cfa::aavso
INTERNET: aavso@cfa.harvard.edu
Tel. 617-354-0484 FAX 617-354-0665

AAVSO ALERT NOTICE 197 (January 27, 1995)

OBSERVATIONS OF CATACLYSMIC VARIABLES FOR ASTRO-2, EUVE, VOYAGER,
AND ASCA SATELLITES

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
variables.

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 aavso@cfa.harvard.edu. 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.

REMINDER REGARDING OUTBURST OF 0749+22 U GEMINORUM

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.

Chart links are obsolete; 11/2013 create charts using VSP at http://www.aavso.org/vsp

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
research.

Good observing!

Janet A. Mattei
Director

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