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 234 (December 20, 1996) RARE OUTBURST OF 1858+42 V493 LYRAE We have been informed by G. Hanson, Cave Creek, AZ, of the rare outburst of V493 Lyrae [R.A. 18h 59m 58s, Decl. +42o 50.4' (1950)]. Recent observations of V493 Lyr include: Dec. 14.71 UT, 14.7, J. Pietz, Erftstadts, Germany; 15.7611, 14.5 CCD, L. T. Jensen, Farum, Denmark; 14.76, 14.7, Pietz; 18.0785, 13.8:, G. Hanson, Cave Creek, AZ; 15.752, 14.1, Jensen; 19.0938, 13.7:, Hanson (Pietz and Jensen via vsnet). Three confirmed outbursts of V493 Lyr have been recorded in the AAVSO International Database since the star was added to the AAVSO visual observing program in August 1993. Outbursts appear to last approximately 10 - 16 days. The last outburst of V493 Lyr recorded in the AAVSO International Database was in November 1995, when it reached visual magnitude 13.6 at maximum. There are also a few unconfirmed single observations showing V493 Lyr around magnitude 14. Accompanying is a 'd' scale AAVSO preliminary chart for V493 Lyr. Please monitor this star closely throughout its outburst and afterwards, and report your observations to AAVSO Headquarters. SECOND SET OF OBSERVATIONS SCHEDULED IN INTERNATIONAL OBSERVING CAMPAIGN ON 1813+49 AM HERCULIS As mentioned in AAVSO Alert Notice 218, 1996 marks the 20th anniversary of the discovery of the magnetic cataclysmic variable AM Her [R.A. 18h 14m 59s, Decl. +49o 50.8' (1950)]. The first phase of the international multi-satellite, multi-observatory, multiwavelength observing campaign organized to celebrate this anniversary (discussed in depth in AAVSO Alert Notice 218) has been carried out by Dr. Boris Gaensicke, Universitaetssternwarte Goettingen, Germany, and his colleagues around the world. A second set of observations, with the Hubble Space Telescope, has been scheduled by Dr. Gaensicke and his colleagues for January 3 - 6, 1997. Presently, AM Her is in its high state, to which it has returned after being in its low state for several weeks this summer. Please monitor AM Her closely from now until the end of January, and report your observations to AAVSO Headquarters, especially if you see AM Her going into its low state, so we may alert the astronomers involved in this international campaign. Please use the AAVSO preliminary 'd' and 'f' scale charts of AM Her issued with AAVSO Alert Notice 218. CHARTS AVAILABLE ON AAVSO FTP SITE AND AAVSO HOME PAGE We have prepared electronic copies of the AAVSO charts of AM Her and V493 Lyr mentioned in this Alert Notice. They are available from our FTP site in the following directories: AM Her: ftp.aavso.org (198.116.78.2), in /pub/alert218 V493 Lyr: ftp.aavso.org (198.116.78.2), in /pub/alert234 The charts also be accessed through our Web site at the following address: http://www.aavso.org 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. If you are cut off when you telephone in your observations, please wait a few minutes and call back to complete your call. We have learned that if someone calls to leave observations on the answering machine and while they are speaking someone else calls, the first person may be cut off. We also encourage observers to send observations by fax to 617-354-0665 or by e-mail through the Internet to observations@aavso.org. We would appreciate it very much if you would report your observations in Universal Time. Many thanks for your valuable astronomical contributions and your efforts. Happy New Year! Good observing! Janet A. Mattei Director Note of thanks: My sincere thanks to Elizabeth Waagen, my Senior Technical Assistant and the AAVSO staff who published and mailed out the Alert Notice 233 while I was away working on collaborative Hipparcos projects and preparations for our 86th Spring Meeting on Variable Stars: New Frontiers in Sion, St. Luc, Switzerland.