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              Tel. 617-354-0484   FAX 617-354-0665

            AAVSO ALERT NOTICE 242 (November 3, 1997)


We  have been informed by Thomas Burrows (Novato, CA) and Patrick
Schmeer (Bischmisheim, Germany) that the dwarf nova type (SU  UMa
subclass)  cataclysmic variable EF Peg is  in  superoutburst,  as
indicated  by the following observations: Nov 1.93 UT, <13.0  (P.
Schmeer);  2.1868, 11.4 (Burrows); 2.713, 11.1 (Schmeer);  2.750,
10.8  (Schmeer);  2.760, 10.7 (Schmeer); 2.835.  10.7  (Schmeer);
3.0771, 11.2 (G. Hanson, Cave Creek, AZ); 3.1604, 10.9 (R. Royer,
Lakewood,  CA);  3.1750, 11.2 (Hanson); 3.1951,  11.6  (Burrows);
3.2076,  11.3  (Hanson); 3.779, 11.2 (E. Broens,  Mol,  Belgium);
3.795, 11.3 (E. Muyllaert, Oostende, Belgium).

The  last  two superoutbursts of EF Peg were in October 1991  and
January  1995  (see AAVSO Alert Notice 196) and  they  were  both
first  detected by P. Schmeer.  Both superoutbursts lasted  about
three weeks. The orbital period of the system was estimated to be
2.05  hours  from  the observed superhump period  of  2.09  hours
during  the  1991  superoutburst (see  S.  Howell  et  al.  1993,
P.A.S.P., 105, 579).

EF  Peg has a close companion about 5 arcseconds away at position
angle 305 degrees.  In making a magnitude estimate, observers are
recommended  to  use  high magnification and to  be  particularly
careful of this companion. When reporting observations of EF  Peg
during  outburst,  please indicate whether  your  estimate  is  a
combined magnitude or not.

Please  monitor  the current superoutburst of EF Peg,  using  the
accompanying  "f"  scale  (5"/1mm) AAVSO preliminary  chart,  and
report  your observations to AAVSO Headquarters. This  chart  has
been  been  posted on our ftp site; see below for details.   When
reporting observations please indicate the source and the date of
the chart, as well as the magnitude of the comparison stars used.

Observers, particularly those using CCDs are encouraged to search
for  superhumps  (small amplitude, periodic  oscillations  during
superoutburst)  by observing EF Peg every three to  five  minutes
for several hours. Please report the time of your observations to
four decimal places of the day.

Also posted on our ftp site is AAVSO Alert Notice 196 which gives
details  of the Jan. 1995 superoutburst of EF Peg, together  with
the  history  of  the comparison star magnitude sequence  of  the
AAVSO chart.

We  congratulate  Tom  and  Patrick on their  detection  of  this
outburst of EF Peg!

and RXTE

We  are  collaborating with astronomers from  Lawrence  Livermore
National  Laboratory in the observations of U Gem in an  exciting
observing  program  that  will involve  the  Extreme  Ultraviolet
Explorer (EUVE) and the Rossi X-ray Timing Explorer (RXTE). These
satellites  have been scheduled to observe U Gem as a  target-of-
opportunity  object  as soon as it starts to  go  into  its  next

The  investigating astronomers have requested that we inform them
immediately when U Gem starts to  brighten so that they can cover
the  rise  to maximum with the satellites, particularly with  the
EUVE  which  observed U Gem at maximum during its  December  1993
outburst.  The aim in the forthcoming observations is to  observe
the  rise to maximum in order to fill in the gap. Thus, the early
notification of the outburst is crucial.

Please monitor U Gem closely, and inform us immediately by phone,
fax,  or  email when it starts to brighten, i.e. becomes brighter
than  13.5.  Once U Gem goes into outburst, please send  in  your
observations daily so we may keep the astronomers informed of the
star's  behavior.  The  success of the observing  run  very  much
depends  on your observations and the early alerts and continuous
information we can provide to our colleagues.


Electronic copies of the AAVSO chart of EF Peg mentioned in  this
Alert Notice are available from our FTP site: (, in /pub/alerts/alert242
or (, in /pub/charts/peg/ef_peg

The chart may also be accessed through our Web site at the
following address:

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. We  also  encourage
observers to send observations by fax to 617-354-0665  or  by  e-
mail through the Internet to

Many thanks for your valuable astronomical contributions and your

Good observing!

Janet A. Mattei

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