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                        AAVSO ALERT NOTICE NO. 25


The recurrent nova 200317 WZ Sge is having its third maximum.  Dr. J. Patterson
of University of Texas called last night to inform us that WZ Sge was observed
at magnitude 8.3 on Dec 1.1 UT.  Astronomers at University of Texas suggest
that WZ Sge may be on its way to maximum.  It had been between magnitude 15
and 16.

Two previous outbursts of WZ Sge were in 1913 when it reached magnitude 7.0
photographically, and in 1946, magnitude 8.0, visually.

Our observers are urged to monitor WZ Sge closely.  If it fluctuates, accurate
timing to the minute should be recorded.  Please inform me of its behavior by
phone or mail.  Phone: Headquarters 617-354-0484.

213843b Nova Cygni 1978:  Dr. Ney informs us that the infrared emission from
this nova did not increase as expected, in fact, it is now decreasing.  Our
visual data also indicates that this nova is slowly fading without the
expected sharp drop in brightness.  (Infrared emission is given off whenever
energy released from a stellar object is absorbed and re-radiated by a dust
shell around that object.)  Dr. Ney's calculations indicate that the grains of
the dust shell around the nova did not attain sufficient size to cause the
sharp drop in brightness.  This unexpected result is very interesting.  It was
believed that only "peculiar" novae that drop sharply in brightness about two
months after maximum, such as DQ Her, NQ Vul, Nova Ser 1978, etc., emit
infrared emission due to formation of dust shell.  However, Dr. Ney now
believes that almost all novae form dust shell and thus give off infrared
emission.  It is the maximum size attained by the grains in the condensed
dust shell that determines whether the brightness will have a sharp drop or
a gradual decrease.  I wish to extend Dr. Ney's thanks and appreciation to all
of you who are monitoring this nova so closely.

0214-03 o Cet (Mira):  This well-known variable, prototype of its class,
appears to be going through a faint maximum.  The maximum date that was
predicted for the end of October is now revised to the second half of November.
Mira is now about magnitude 5.  It appears that whenever this variable
undergoes a faint maximum, the preceding minimum is wide and the maximum
occurs later than the predicted date.  This was the case in February 1976.
Our observers are urged to monitor Mira closely.

Many thanks!

Clear skies!  Good observing!

Janet A. Mattei

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