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


               AAVSO ALERT NOTICE 229 (September 18, 1996)


REQUEST AND REMINDER TO MONITOR 2138+43 SS CYGNI FOR OBSERVATIONS WITH HST
AND WITH EUVE, RXTE, AND SAX

Astronomers at the Space Telescope Science Institute will be observing SS Cyg
on September 26 with the Hubble Space Telescope (HST).  They hope to observe
SS Cyg at minimum.  Please report your observations of SS Cyg - even if it is
at minimum - to AAVSO Headquarters daily September 23 through 28, so that we
may inform the astronomers of SS Cyg's status at the time of their observations.

Also, observers are reminded (see AAVSO Alert Notices 221 and 222) to keep a
very close eye on SS Cyg and inform us immediately when it begins to brighten,
i.e., becomes brighter than magnitude 11.5, so that we may inform the
astronomers with whom we are collaborating in the observation of SS Cyg with
the Extreme Ultraviolet Explorer (EUVE), Rossi X-ray Timing Explorer (RXTE)
(formerly X-ray Timing Explorer, XTE, and renamed in memory of X-ray astronomy
pioneer Bruno Rossi, who died in 1993), and Satellite per Astronomia X (SAX)
(Italy's first X-ray astronomy satellite).

Timely notification of the onset of the outburst and the behavior of SS Cyg
throughout the outburst is essential to this collaborative effort.  Please
report your observations daily so we may inform our colleagues.


REMINDER - 0207-63 WX HYDRI TO BE OBSERVED WITH HUBBLE SPACE TELESCOPE

Our southern hemisphere observers, in particular, are reminded (see AAVSO
Alert Notice 225) to monitor WX Hyi closely until the end of the year and to
keep us informed of its behavior, so that we may notify the astronomers at the
Space Telescope Science Institute who are planning to observe this SU UMa-type
cataclysmic variable with the Hubble Space Telescope on September 24, and also
in November.  They have already made one set of observations, in August, as
scheduled.

If you do not have the charts for this far-southern object, please let us know.


The answering machine at AAVSO Headquarters is on nights and weekends for your
convenience.  Please call our charge-free number (800-642-3883) to report your
observations.  If you are cut off when you telephone in your observations,
please wait a few minutes and call back to complete your call.  We have learned
that if someone calls to leave observations on the answering machine and while
they are speaking someone else calls, the first person may be cut off.  We
also encourage observers to send observations by fax to 617-354-0665 or by
e-mail through the Internet to observations@aavso.org.  We would appreciate it
very much if you would report your observations in Universal Time.


Many thanks for your valuable astronomical contributions and your efforts.

Good observing!

Janet A. Mattei
Director