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Alert Notice 210: 1147+49 BC Ursae Majoris in outburst AND Reminders on 0409-71 VW Hydri and 2138+43 SS Cygni AND Current activity on some cataclysmic variables

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 210 (July 7,1995)

1147+49 BC URSAE MAJORIS IN OUTBURST

The dwarf nova-type cataclysmic variable (SU UMa subclass) BC UMa is undergoing an
outburst, as indicated by the following observations:

Ju12.965 UT, < 14.0, G. Poyner, Birmingham, UK; 6.1576, 14.0, D. York, Abiquiu, NM;
6.1694, 13.9, York; 6.1868, 13.8, York; 6.2076, 13.4, York; 6.2292, 13.0, York; 7.10, 12.4, G.
Dyck, Assonet, MA; 7.1542, 13.2, York; 7.1708, 13.2, York; 7.2347, 13.0, T. Burrows,
Novato, CA.

The last recorded outburst of BC UMa in the AAVSO International Database was in April
1994, when it reached magnitude 12.0 and the outburst lasted 9 days. Following this
outburst, several observers reported it brightening to magnitude 14.0 five days after the star
returned to minimum. The reported blue magnitude range of the star m the General
Catalogue of Variable Stars is 10.9 - 18.3 B; in the AAVSO International Database, the
visual range is 10.9 - 17.2.

Accompanying are "d" and "e" scale AAVSO preliminary charts prepared by Charles Scovil.
We have also prepared electronic copies of these charts, which are available from our FTP
site, ftp.aavso.org (198.116.78.2), in /pub/alert210.

Please observe BC UMa closely and report your observations to AAVSO Headquarters.
Observers are also strongly encouraged to search for the presence of superhumps during
this outburst by observing it every five minutes, reporting the time to 4 decimals places of
the Julian Date.

REMINDERS ON 0409-71 VW HYDRI AND 2138+43 SS CYGNI

0409-71 VW Hyi. Thanks to observers in Chile and South Africa (W. Liller, J. Hers, D.
Overbeek) and in New Zealand, VW Hyi is being closely monitored to catch the next
normal outburst for forthcoming satellite observations. Please continue to keep a close eye
on VW Hyi and report your observations to AAVSO Headquarters, particularly when it
goes into outburst, predicted to occur within the coming two weeks.

2138+43 SS Cyg. SS Cyg has just gone through a short outburst, in which the rise was
rather slow. Unfortunately, IUE observations could not be carried out during this outburst.
Observers are reminded to keep a close eyeon SS Cyg and report your observations, so
that the next time it has an anomalous, slow-rise outburst it can be monitored with IUE.

CURRENT ACTIVITY ON SOME CATACLYSMIC VARIABLES

0959+68 CH UMa. This dwarf nova type cataclysmic variable (U Gem subclass) is
brightening, as indicated by the following observations: Jun 28.946 UT, < 14.0, G. Poyner,
Birmingham, England; 28.957, < 13.7, T. Vanmunster, Landen, Belgium; 29.937, < 14.1,
Vanmunster; 29.981, 14.7, Poyner; 30.942, < 14.0, E. Broens, Mol, Belgium; 30.942, < 13.7,
Vanmunster; Jul 2.962, < 14.3, Poyner; 3.962, 14.7, Poyner; 7.1618 13.4, D. York, Abiquiu,
NM.

CH UMa has been having minor brightenings during its quiescence, the most recent of
which was in April. Please monitor CH UMa closely to determine whether this is the start
of an outburst or another active quiescent period. The last recorded outburst of CH UMa
in the AAVSO International Database was in June 1994, when it reached magnitude 11.6.

1454+41 TT Boo. The dwarf-nova cataclysmic variable (SU UMa subclass) TT Boo is in
outburst, as indicated by the following observations: Jul 2.966 UT, < 14.8, G. Poyner,
Birmingham, England; 3.964, 12.9, Poyner; 4.1042, 12.8, J. Bortle, Stormville, NY; 4.1188,
12.8, R. Stewart, Fairlawn, NJ; 4.1597,13.0, J. McKenna, Upper Montclair, NJ; 5.979, 12.7,
L. Jensen, Fanun, Denmark; 7.10,12.8, G. Dyck, Assonet, MA.

The last recorded outburst of TT Boo was in March 1995, when it reached magnitude 12.4.

1640 +25 AH Her. The cataclysmic variable AH Her is undergoing a bright outburst, as
indicated by the following observations: Jun 28.1014 UT, 14.2, J. Bortle, Stormville, NY;
28.1910, < 13.4, B. Dillon, Missouri City, TX; 30.943, 13.9, J. Pietz, Erftstadts, Germany;
Jul 1.2410, < 13.4, Dillon; 2.2292, 12.8, Dillon; 2.926, 11.6, L. Jensen, Farum, Denmark;
3.1139, 11.0, Bortle; 4.1069, 11.1, Bortle; 4.1292, 11.2, B. Stewart, Fairlawn, NJ; 5.86, 11.3,
J. Gunther, St. Oze, France; 5.928, 11.5, Jensen; 6.1507, 11.0, D. York; Abiquiu, NM;
7.1639, 11.1, York; 7.2028,11.3, Dillon.

1904+43 MV Lyr. The nova-like cataclysmic variable MV Lyr continues to be in its faint
state, as indicated by the following observations: Jun 29.1111 UT, 14.8, J. Bortle,
Stormville, NY; 29.94, 14.8, R. Szabo, Hunyadi, Hungary; 29.942, < 14.0, L. Jensen, Farum,
Denmark; 29.967, 15.0, J. Pietz, Erftstadts, Germany; 30.1924, 15.1, Bortle; 30.968, < 14.8,
E. Broens, Mol, Belgium; 30.975, 15.2, Pietz; Ju13.1194, 15.2, Bortle; 5.944, < 14.0, Jensen;
6.1604,15.1, D. York, Abiquiu, NM; 7.1688,14.8, York.

A chart for MV Lyr appears in AAVSO Alert Notice 207.

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

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 observationsQa aavso.org.

When telephoning in observations, please state the name of the star, the magnitude, and
the time of the observation. Please speak clearly. The preferred time is either your local
time (be sure to state the time zone and whether it is Standard or Daylight Savings Time)
or Universal Time. You do not need to give the designation of the star. Please also
include the comparison stars you have used in making the observation.

Many thanks for your significant astronomical observations.

Good observing!

Janet A. Mattei
Director

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