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			25 Birch Street, Cambridge, MA 02138 USA
		   BITNET: aavso@cfa8 SPAN: nssdca::cfa8::aavso 
			INTERNET: aavso@cfa0.harvardedu 
		   Tel. 617-354-0484	FAX 617-354-0665

		AAVSO ALERT NOTICE 168 (February 18,1993)


The SU UMa type dwarf nova 0829+53 SW UMa is undergoing a superoutburst, as 
indicated by the following observations:

Feb.	16.13 UT	< 13.5	B. Granslo (Fjellhamar, Norway)
	16.778	10.6	L. Szentasko (Budapest, Hungary)
	16.795	10.7	R. Fidrich (Ibafa-Gyurufu, Hungary)
	16.970	10.9	O. Gabzo (Sheffagim, Israel)
	17.111	10.9	B. Granslo
	17.743	11.2	H. Dahle (Oslo, Norway)
	17.762	11.0	O. Midtskogen (Tranby, Norway)
	17.872	11.1	E. Ofek (Tel Aviv, Israel)
	18.034	12.0	J. Bortle (Stormville, NY)
	18.083	11.9	R. Stewart (Rochelle Park, NJ)
	18.106	11.0	D. York (Abiquiu, NM)
	18:132	11.7	R. Stewart
	18.146	11.0	D. York

We very much appreciate these AAVSO observers alerting us to this rare superoutburst.

Recent superoutbursts of this cataclysmic variable have occurred in March 1992, when it 
reached maximum magnitude 10.5; February 1991, when it reached 11.2; and March 1990, 
when it reached 10.2. At superoutburst, the star is usually brighter than magnitude 12.0 for 
10 to 20 days.

SW UMa was classified as a dwarf nova of SU UMa type in 1986, when astronomers at 
McDonald Observatory of the University of Texas obtained an orbital period of 84.0 
minutes during its superoutburst at that time.

The superhumps that appear during superoutburst may be observable visually. They have a 
small amplitude of about 0.2 magnitude and a period 2 to 3 percent longer than the orbital 
period of the star. Observers are encouraged to make observations every 5 to 10 minutes 
and record the exact time of observation to three decimal places, in an effort to detect 

Enclosed is a finder chart of SW UMa. Please monitor this variable closely during this rare 
superoutburst and call in your observations to Headquarters so we may transmit them to 
the astronomical community.


The cataclysmic variable 1215-17 - Crv (a star that was discovered in outburst by C. W. 
Tombaugh on photographic plates taken in March 1931 and noted as "nova suspect", and 
later confirmed to be a dwarf nova type cataclysmic variable in the article by Levy, D. H.,
Howell, B. S., Kreidl, T. J., Skiff, B. A., Tombaugh, C. W., in 1990, Publ. Astron. Soc. 
Pacific, 102, 1321) is undergoing an outburst, as reported by Dr. Steve Howell, who is 
observing in Hawaii.

Enclosed is a finder chart for - Crv. Please monitor this star as much as possible, using the 
enclosed sequence for R Crv, which is close to - Crv, and call in your observations to 


The dwarf nova 0830 + 21 CC Cnc is undergoing an outburst, as indicated by the following 
observations: Feb. 15.05 UT 13.3, J. Bortle (Stormville, NY); 16.17, 13.1, M. Adams 
(Melbourne, FL);18.03,13.7, Bortle;18.14,13.3, R. Stewart (Rochelle Park, NJ).

Please use the enclosed CC Cnc chart, from the Royal Astronomical Society of New 
Zealand and with the AAVSO photoelectric sequence by R. Stanton, to monitor this star 
and report your observations to Headquarters.


0749+22 U Geminorum. This cataclysmic variable is still at quiescence. Please follow it 
closely and phone in your observations if you see it brighter than magnitude 13.5, as several 
astronomers are interested in monitoring it during an outburst.

1137+72 YY Draconis. Please keep a close eye on this star and inform us of its activity 
whenever it brightens.

2318+17 IP Pegasi. Please monitor this cataclysmic variable closely and call in your 
observations when it starts to brighten. Astronomers are interested in observing it with the 
Hubble Space Telescope during an outburst.

The answering machine (617-354-0484) is on nights and weekends for your convenience.

Many thanks for all your efforts and valuable contributions. 

Clear skies and good observing!

Janet A. Mattei 

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