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			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, ItJE 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 AAYSO Alert Notice 207.

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

Keywords:
AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484