THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS 25 Birch Street, Cambridge, MA 02138 USA Tel. 617-354-0484 Fax 617-354-0665 INTERNET: aavso@aavso.org * * * AAVSO NEWS FLASH * * * Subject: Occultation of R Leo, YZ Cnc, AM Cas, No. 248 V516 Cyg, AB Dra, TZ Per, FO Per January 14, 1997 ________________________________________________________________________________ OCCULTATION OF R LEONIS The long period variable R Leo will be occulted on Thursday morning. Below is the message that we received today from David Dunham (director of IOTA) which gives detailed information on this occultation: ******************************************************************* Date: Wed, 14 Jan 1998 03:10:21 -0500 From: Joan and David Dunham Subject: R Leo occ'n Thurs. am; Jan. 17 path updates The Mira variable R Leonis has perhaps the largest angular diameter (0.067" or 67 mas) of any star in the sky, not counting the Sun. The star, also known as Z.C. 1442, will be occulted by the 93% sunlit waning Moon on Thursday morning, January 15th, over all of the contiguous U.S.A., the Alaska panhandle and eastern Aleutian islands, southern Canada except for Newfoundland, easternmost Nova Scotia, and the Gaspe Peninsula, which are north of the northern limit, northern Mexico, most of the Caribbean Sea, and most of Venezuela. I observed the star visually earlier tonight, and it seems to be about mag. 7.5. The event should be observable without too much difficulty with 8-inch and larger telescopes, if the sky is clear and you watch in the right place for the dark-limb reappearance. At this percent sunlit, the Watts angle should be a better guide than the cusp angle - that is, use lunar features by watching at that point on the western lunar limb that has a selenographic latitude that is approximately equal to the Watts angle - 270. The Watts angle and U.T. of the reappearance are given for almost 300 North American cities on IOTA's Web site at http://www.sky.net/~robinson/iotandx.htm A map showing the region of visibility of the occultation is also there. High-speed photometric observations would be valuable for learning more about this interesting star. The reappearance will occur at 8:44 U.T. (3:44 am EST) in the Washington, DC area at a cusp angle of 67N and a Watts angle of 295 deg., near the southern end of Mare Crisium, but it will probably be cloudy here by then. Unfortunately, this will be North America's last chance to observe an occultation of this star for awhile. Another occultation will occur at about 3h U.T. April 7, visible from almost the same region, but the star should then be near minimum light (11th mag.); the Moon will be 80% sunlit waxing (so the disappearance will be on the dark side). On June 28th, there will be a final occultation in the current series by the 17% sunlit waxing Moon, but it will be visible only from the vicinity of Hudson Bay. ******************************************************************* ----------------------------------------------------------------------------- YZ CANCRI The dwarf nova type (SU UMa subclass) cataclysmic variable YZ Cnc appears to be in outburst as indicated by the following observations: AAVSO Observer UT Mag. Initials JAN 11.1710 14.80 CCDV ZRE JAN 14.1181 11.5 SWT ----------------------------------------------------------------------------- AM CASSIOPEIAE The dwarf nova type (Z Cam subclass) cataclysmic variable AM Cas is in outburst as indicated by the following observations: AAVSO Observer AAVSO Observer UT Mag. Initials UT Mag. Initials JAN 08.4167 15.5: HSG JAN 14.0097 13.2 BRJ JAN 12.011 13.7 CGF JAN 14.0507 12.7 SWT JAN 12.990 12.5 CGF ----------------------------------------------------------------------------- V516 CYGNI The dwarf nova type (SS Cyg subclass) cataclysmic variable V516 Cyg is in outburst as indicated by the following observations: AAVSO Observer UT Mag. Initials JAN 03.0882 <15.5 HSG JAN 11.963 13.8 CGF JAN 13.9861 13.3 BRJ ----------------------------------------------------------------------------- AB DRACONIS The dwarf nova type (Z Cam subclass) cataclysmic variable AB Dra is in outburst as indicated by the following observations: AAVSO Observer AAVSO Observer UT Mag. Initials UT Mag. Initials JAN 10.807 13.9 PYG JAN 12.983 12.8 CGF JAN 12.008 13.4 CGF JAN 13.9896 12.7 BRJ ----------------------------------------------------------------------------- TZ PERSEI The dwarf nova type (Z Cam subclass) cataclysmic variable TZ Per is in outburst as indicated by the following observations: AAVSO Observer AAVSO Observer UT Mag. Initials UT Mag. Initials JAN 10.881 14.4: PYG JAN 14.0125 12.7 BRJ JAN 12.0 <13.3 CGF JAN 14.0549 12.7 SWT JAN 13.023 13.3 CGF JAN 14.103 12.8 MKJ ----------------------------------------------------------------------------- FO PERSEI The dwarf nova type cataclysmic variable FO Per is in outburst as indicated by the following observations: AAVSO Observer UT Mag. Initials JAN 08.4292 <15.0 HSG JAN 14.0139 13.3 BRJ JAN 14.0604 13.5 SWT ----------------------------------------------------------------------------- We thank the following contributors for the data that they have provided for this News Flash: BRJ - J. Bortle, USA PYG - G. Poyner, England CGF - G. Chaple, USA SWT - R. Stewart, USA HSG - G. Hanson, USA ZRE - R. Zissell, USA MKJ - J. McKenna, USA Please monitor these and other variable stars closely and phone-in, fax, or e-mail your observations to the AAVSO. Good observing! Janet A. Mattei NOTE OF THANKS: My sincere thanks to Rebecca Pellock for preparing and sending out the News Flashes so capably, and to the observers for their valuable observations that made up the News Flashes while I was way attending the Meeting of the American Astronomical Society. The AAS meeting, the largest ever, with over 2000 attendees was very well organized with excellent scientific program and activities. It was extremely satisfying to see so many friends and colleagues, hear of their research, and share news about our activities. At this meeting I presented a poster paper co-authored with Grant Foster, on the Studies of Long Period Variables. ________________________________________________________________________________ Symbols may include: < = fainter than magnitude given (variable not seen) : = uncertain CCDV = Charge-coupled device with (V) filter If you would like to contribute to AAVSO NEWS FLASH, please send observations of unusual variable star activity to: observations@aavso.org Those who wish to subscribe (free of charge) or unsubscribe to NEWS FLASH may do so by sending a message to: observations@aavso.org If you would like data from the AAVSO International Database for research purposes, please send your request to: Janet Mattei, AAVSO Director, at aavso@aavso.org We look forward to including your observations in future editions of AAVSO NEWS FLASH! _____________________________________________________________________________