THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS 25 Birch Street, Cambridge, MA 02138 USA Tel. 617-354-0484 Fax 617-354-0665 http://www.aavso.org * * * AAVSO NEWS FLASH * * * Subject: 1813-25B V4641 SGR 2335+12 HX PEG No. 969 1934+30 EM CYG May 23, 2002 ---------------------------------------------------------------------------- 1813-25B V4641 SAGITTARII As mentioned in AAVSO News Flash No. 966 the microquazar V4641 SGR is in outburst. Microquazars are a class of X-Ray novae. Their X-Ray and optical emissions are thought to be from an accretion disk around a neutron star or black hole. This object has been showing very rapid (seconds) and significant magnitude variations. V4641 Sgr has been oscillating between visual magnitude 11.5 and 13.0 with a time scale of 1 day. Variations of almost .5 magnitude have been seen within minutes. Recent data showing these oscillations is included below. Please continue to keep a very close eye on this very unusual and interesting object. AAVSO Observer AAVSO Observer UT Mag. Initials UT Mag. Initials MAY 16.1390 13.4 MLF MAY 22.4287 12.32 CCD WJD MAY 17.5690 13.4 SRX MAY 22.4295 12.45 CCD WJD MAY 19.6990 11.5 SRX MAY 22.4303 12.48 CCD WJD MAY 19.7040 11.5 SRX MAY 22.4310 12.43 CCD WJD MAY 19.7160 11.5 SRX MAY 22.4318 12.27 CCD WJD MAY 19.7230 11.5 SRX MAY 22.4326 12.43 CCD WJD MAY 20.4291 12.2 LMK MAY 22.4334 12.37 CCD WJD MAY 20.4763 12.6 LMK MAY 22.4341 12.47 CCD WJD MAY 20.7350 12.8 SRX MAY 22.4349 12.45 CCD WJD MAY 21.4085 12.64 CCDV WJD MAY 22.4357 12.37 CCD WJD MAY 21.4089 12.76 CCDV WJD MAY 22.4365 12.14 CCD WJD MAY 21.4094 12.82 CCDV WJD MAY 22.4372 12.15 CCD WJD MAY 21.4099 12.85 CCDV WJD MAY 22.4380 12.21 CCD WJD MAY 21.4132 12.58 CCDV WJD MAY 22.4388 12.28 CCD WJD MAY 21.4140 12.63 CCDV WJD MAY 22.4396 12.37 CCD WJD MAY 21.4147 12.61 CCDV WJD MAY 22.5628 12.1 PEX MAY 21.4155 12.70 CCDV WJD MAY 22.5635 12.0 PEX MAY 21.4163 12.75 CCDV WJD MAY 22.5642 12.4 PEX MAY 21.4171 12.69 CCDV WJD MAY 22.5649 12.2 PEX MAY 21.4178 12.66 CCDV WJD MAY 22.5656 12.3 PEX MAY 21.4186 12.81 CCDV WJD MAY 22.5663 12.7 PEX MAY 21.4194 12.81 CCDV WJD MAY 22.5670 12.1 PEX MAY 21.4202 12.77 CCDV WJD MAY 22.5677 11.7 PEX MAY 21.4209 12.71 CCDV WJD MAY 22.5684 12.0 PEX MAY 21.4217 12.76 CCDV WJD MAY 22.5691 12.2 PEX MAY 21.4225 12.65 CCDV WJD MAY 22.5698 12.2 PEX MAY 21.4233 12.80 CCDV WJD MAY 22.5705 12.2 PEX MAY 21.4247 12.66 CCDV WJD MAY 22.5712 12.1 PEX MAY 21.4255 12.65 CCDV WJD MAY 22.5719 12.0 PEX MAY 21.4263 12.72 CCDV WJD MAY 22.5726 12.0 PEX MAY 21.4271 12.95 CCDV WJD MAY 22.5733 12.1 PEX MAY 21.4278 12.58 CCDV WJD MAY 22.6111 12.2 PEX MAY 21.4286 12.74 CCDV WJD MAY 22.6118 12.1 PEX MAY 21.4294 13.05 CCDV WJD MAY 22.6125 12.1 PEX MAY 21.4298 12.9 LMK MAY 22.6132 12.1 PEX MAY 21.4302 12.70 CCDV WJD MAY 22.6139 12.3 PEX MAY 21.4310 12.91 CCDV WJD MAY 22.6145 12.5 PEX MAY 21.4317 12.78 CCDV WJD MAY 22.6153 12.6 PEX MAY 21.4325 13.14 CCDV WJD MAY 22.6160 12.6 PEX MAY 21.4341 12.93 CCDV WJD MAY 22.6167 12.5 PEX MAY 21.4348 12.85 CCDV WJD MAY 22.6174 12.6 PEX MAY 21.4356 12.79 CCDV WJD MAY 22.6181 12.6 PEX MAY 21.4958 12.5 LMK MAY 22.6188 12.6 PEX MAY 21.5555 12.9 PEX MAY 22.6194 12.7 PEX MAY 22.4110 12.10 CCD WJD MAY 22.6201 12.7 PEX MAY 22.4118 12.16 CCD WJD MAY 22.6208 12.6 PEX MAY 22.4125 11.99 CCD WJD MAY 22.6215 12.6 PEX MAY 22.4131 11.8: LMK MAY 22.6222 12.5 PEX MAY 22.4131 12.3 LMK MAY 22.6229 12.5 PEX MAY 22.4132 11.8: LMK MAY 22.6236 12.4 PEX MAY 22.4133 12.3 LMK MAY 22.6243 12.5 PEX MAY 22.4133 11.91 CCD WJD MAY 22.6257 12.5 PEX MAY 22.4141 11.94 CCD WJD MAY 22.6264 12.4 PEX MAY 22.4149 12.08 CCD WJD MAY 22.6271 12.4 PEX MAY 22.4156 12.23 CCD WJD MAY 22.6278 12.5 PEX MAY 22.4164 12.19 CCD WJD MAY 22.6285 12.4 PEX MAY 22.4173 12.26 CCD WJD MAY 22.6292 12.2 PEX MAY 22.4180 12.36 CCD WJD MAY 22.6299 12.2 PEX MAY 22.4188 12.38 CCD WJD MAY 22.6306 12.2 PEX MAY 22.4196 12.35 CCD WJD MAY 22.6313 12.1 PEX MAY 22.4204 12.30 CCD WJD MAY 22.6319 12.1 PEX MAY 22.4212 12.34 CCD WJD MAY 22.7710 11.7 SRX MAY 22.4219 12.21 CCD WJD MAY 22.7760 11.6 SRX MAY 22.4227 12.29 CCD WJD MAY 22.7980 11.7 SRX MAY 22.4235 12.47 CCD WJD MAY 22.8270 11.6 SRX MAY 22.4243 12.53 CCD WJD MAY 23.0620 11.3 MLF MAY 22.4250 12.44 CCD WJD MAY 23.0750 11.8 MLF MAY 22.4258 12.42 CCD WJD MAY 23.4583 13.0 LMK MAY 22.4266 12.37 CCD WJD MAY 23.4604 12.1 LMK MAY 22.4274 12.54 CCD WJD MAY 21.5000 12.8 LMK MAY 22.4281 12.39 CCD WJD ---------------------------------------------------------------------------- 1934+30 EM CYGNI The dwarf nova type (Z CAM subclass) cataclysmic variable EM CYG appears to be in outburst, as indicated by the following observations: AAVSO Observer AAVSO Observer UT Mag. Initials UT Mag. Initials MAY 22.3111 13.9 SXN MAY 23.4305 12.5 LMK MAY 22.4722 13.7 LMK ---------------------------------------------------------------------------- 2335+12 HX PEGASI The dwarf nova type cataclysmic variable HX PEG appears to be in outburst, as indicated by the following observations: AAVSO Observer UT Mag. Initials MAY 22.8210 13.0 SRX ---------------------------------------------------------------------------- We thank the following contributors for the data that they have provided for this News Flash: LMK - M. LINNOLT, USA SRX - R. STUBBINGS, AUSTRALIA MLF - I. MONARD, SOUTH AFRICA SXN - M. SIMONSEN, USA PEX - A. PEARCE, AUSTRALIA WJD - J. WEST, 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, Director Rebecca Pellock, Technical Assistant ____________________________________________________________________________ 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 visiting the following web page: http://www.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 An archive of past issues of the News Flash is available at the following web page: http://www.aavso.org/newsflash/ We look forward to including your observations in future editions of AAVSO NEWS FLASH! ____________________________________________________________________________