THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
BITNET: aavso@cfa8 SPAN: nssdca::cfa8::aavso
Tel. 617-354-0484 FAX 617-354-0665
AAVSO ALERT NOTICE 168 (February 18,1993)
SUPEROUTBURST OF 0829+53 SW URSAE MAJORIS
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 superhumps.
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.
SUPEROUTBURST OF 1215-17 - CRV (TOMBAUGH'S NOVA DWARF NOVA)
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 Headquarters.
OUTBURST OF 0830+21 CC CANCRI
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!
files: SW UMa d and e scale charts; - Crv d scale preliminary chart; CC Cnc RASNZ e scale chart (#534) w/annotated sequence