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 237 (February 19, 1997) OBSERVATIONS OF DWARF NOVAE REQUESTED Astronomers at Keele University, England, will be observing dwarf novae in outburst with the 4-meter William Herschel Telescope between February 24 and 26 in order to obtain spectroscopy. They have requested our assistance in monitoring dwarf novae, and in particular the dwarf novae listed below, in order to know which systems are in outburst at the time of their observations: Design. Star R. A. (1950) Decl. (1950) 0130+50 KT Per [01h 34m 02s +50o 42.1'] 0523-03 V1159 Ori [05 26 29 -03 36.2] 0547-05 CN Ori [05 49 40 -05 25.7] 0749+22 U Gem [07 52 08 +22 08.1] 0814+73 Z Cam [08 19 40 +73 16.4] 0855+18 SY Cnc [08 58 13 +18 06.1] Your assistance will be crucial to the success of this observing run. Please monitor these and other dwarf novae closely until the end of February and report your observations to AAVSO Headquarters daily by email, fax, or telephone so we may inform the astronomers. REQUEST TO MONITOR 1807+69 3C 371 (DRACO) As announced in AAVSO News Flash No. 105, astronomers at the Osservatorio Astronomico di Brera, Italy, have been observing since January and will be observing the Blazar 3C 371 in Draco [RA 18h 07m 18.5s; Dec +69o 48' 58"(2000)] intensively with the Infrared Space Observatory (ISO) satellite over the coming months. They have requested our assistance in providing optical observations before, during, and after the ISO observations. The approximate schedule of the remaining satellite observations is as follows: 20 Feb +/-1 day 2 Mar 20 Mar +/-1 day 23 Feb +/-1 day 3 Mar 27 Mar +/-1 day 27 Feb 4 Mar 3 Apr +/-1 day 28 Feb 8 Mar +/-1 day 10 Apr +/-1 day 1 Mar 13 Mar +/-1 day Accompanying are AAVSO preliminary 'b', 'd', and 'e' scale charts of 3C 371 prepared by C. Scovil from a British Astronomical Association chart by J. Toone. Please use these charts dated 1/1997 to monitor 3C 371, which has an optical range of 14.3 - 16.1 in the AAVSO data files, and report your observations to AAVSO Headquarters by email, fax, or telephone. BRIGHT MAXIMUM OF 0214-03 OMICON CET (MIRA) According to reports received from observers around the world, the long period variable omicron Cet (Mira) is undergoing a very bright maximum. According to observations reported to the AAVSO, its present visual magnitude is 2.4. The magnitude of Mira at maximum can vary significantly from cycle to cycle. The many observations of this star reported to the AAVSO yield the following average magnitudes, showing the rise of Mira to its present brightness: 1997 January 1 - 4.5 visual magnitude January 15 - 3.2 February 1 - 2.5 February 15 - 2.4 According to the prediction made in AAVSO Bulletin 59, Mira should be at maximum in mid-February 1997, and the very small change in brightness since the beginning of February supports this prediction. The last maximum of Mira was in mid-March 1996. Please monitor Mira, the first variable star discovered, and report your observations to the AAVSO with your monthly report. CHARTS AVAILABLE ON AAVSO FTP SITE Electronic copies of the AAVSO charts of 3C 371 mentioned in this Alert Notice are available from our FTP site: ftp.aavso.org (198.116.78.2), in /pub/alerts/alert237 or ftp.aavso.org (198.116.78.2), in /pub/charts/dra/3c_371/ The charts of 3C 371 may 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. Good observing! Elizabeth O. Waagen, Senior Technical Assistant for Janet A. Mattei, Director