THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS 25 Birch Street, Cambridge, MA 02138 USA BITNET: aavso@cfa SPAN: cfa::aavso INTERNET: aavso@cfa.harvard.edu Tel. 617-354-0484 FAX 617-354-0665 AAVSO ALERT NOTICE 207 (May 3, 1995) FADING OF 2055+43 V1057 CYGNI J. E. Bortle, Stormville, NY, has informed us that the FU Orionis-type nebular variable V1057 Cyg has faded abruptly, as indicated by his observations and those of L. Szentasko, Budapest, Hungary, and T. Vanmunster, Landen, Belgium. Recent observations received at AAVSO Headquarters include: Feb 1.0 UT, 12.2, L. Szentasko, Budapest, Hungary; 3.0, 12.1, J. Bortle, Stormville, NY; 3.0, 12.1, S. Papp, Locsei, Hungary; 8.0, 12.1, Szentasko; 9.1645, 12.0, M. Moeller, Timmendorfer Strand, Germany; 9.7368, 12.0, Moeller; 20.0, 12.2, Szentasko; 24.0, 12.4, Szentasko; Mar. 8.18, 12.4, L. Jensen, Farum, Denmark; 10.16, 12.3, Jensen; 22.15, 12.3, Jensen; 23.043, 12.8, Vanmunster; 29.12, 12.5, Jensen; 30.12, 12.5, Jensen; Apr 10.01, 12.6, B. Granslo, Fjellhamar, Norway; 22.04, 13.0, Szentasko; 23.043, 12.8, T. Vanmunster, Landen, Belgium; 26.3264, 13.0, Bortle; 29.05, 12.8, Szentasko; 29.99, 12.8, Granslo; 30.3521, 12.9, Bortle; 30.98, 12.9, Granslo. V1057 Cyg has been in the AAVSO observing program since 1971, when it brightened suddenly to magnitude 9.8; Bortle was the first AAVSO observer to observe this star, at 9.8 in July 1971. Since then, V1057 Cyg has been very well monitored. The majority of the observations in the AAVSO International Database indicate that the star declined slowly from 9.8 to 11.9 by 1983. Since 1983 it has faded very slowly to an average magnitude of 12.0. Bortle points out that the recent abrupt fading of this star may indicate a distinct change in the behavior of V1057 Cyg, and so the star deserves close monitoring. Accompanying are the "d" and "e" scale AAVSO preliminary charts of V1057 Cyg that have been prepared by C. Scovil. Observers are strongly recommended to monitor this star closely, and call in their observations to AAVSO Headquarters. ENDING OF THE SUPEROUTBURST OF 1227+14 AL COMAE BERENICES The superoutburst of this interesting cataclysmic variable has been very well monitored by observers worldwide. It appears that this rare superoutburst has now ended, as shown by the observation of D. York, Abiquiu, NM, on May 3.1792 UT at fainter than 16.0. Accompanying is the light curve of observations of AL Com received at AAVSO since the start of this superoutburst. Analyzing the data, we find that from the start of the outburst on 5 April 1995, AL Com declined to 13.5 in 9 days, at a rate of 0.15 magnitude per day. It was then at standstill for 5 days at magnitude 13.5. Subsequently, it continued to decline, from April 19 at 13.5 to April 30 at 15.0, at a rate of 0.13 magnitude per day. R. Zissell (South Hadley, MA) and G. Walker (Dover, MA) monitored the superhumps of this cataclysmic variable with CCDs. We analyzed the CCD(V) observations obtained by Zissell on the nights of April 6, 11, 23, and 25, using the CLEANEST Fourier Spectrum analysis method developed by Grant Foster at AAVSO Headquarters (see G. Foster, Astron. Journ. 109, p. 1889, April 1995). We find superhump periods ranging from 80.4 to 84.7 minutes with a suggestion of the beating of two close frequencies on April 6 and 11. Particularly from Zissell's CCD(V) observations, we find that the data on April 6 show superhumps with double-peak maxima; on April 11 the amplitude of the superhumps has decreased and the light curve has shifted to double peak minima; on April 23 and 25 the shape of the superhumps is sinusoidal. We will report on these results at the Scientific Paper Session during the 84th Spring meeting of the AAVSO. Checking the 1975 outburst of AL Com, which appears quite similar in behavior to the current one, the data in the AAVSO International Database indicate that the outburst started in mid-March and lasted until mid-April. After it faded to minimum, on June 13 and June 30, 1975, G. Johnson and C. Ford reported the star at 13.9 and 14.0, respectively, and they both independently indicated that there was uncertainty in their estimates, without giving specifics of the uncertainty. These two observations may indicate that AL Com brightened briefly after it reached minimum. Unfortunately, there are no other observations between these two "uncertain" observations to confirm the brightening after the superoutburst of AL Com. Observers are strongly encouraged to continue to monitor AL Com, as long as possible, to determine its current behavior. Since the distribution of AAVSO Alert Notice 206, C. Scovil has prepared a very high-quality finder chart for AL Com which we have, for the first time, put on an electronic FTP retrieval site. This chart may be retrieved from cfa.harvard.edu in .TIF, .GIF, and PostScript forms. We are planning to put more AAVSO charts, as well as other AAVSO materials, on an FTP site, and we will inform you when and how you may retrieve them. We sincerely thank the following observers for their close monitoring of AL Com during this rare superoutburst, and for their contribution to the accompanying light curve: M. Adams, Fort Davis, TX; J. Bortle, Stormville, NY; E. Broens, Mol, Belgium; T. Burrows, Novato, CA; T. Cragg, Coonabarabran, Australia; H. Dahle, Oslo, Norway; W. Dillon, Missouri City, TX; P. Dombrowski, Glastonbury, CT; B. Granslo, Fjellhamar, Norway; J. Griese, Rocky Hill, CT; J. Gunther, Stuze, France; R. Harvan, Leonardstown, MD; G. Hurst, Basingstoke, England; L. Jensen, Farum, Denmark; J. McKenna, Upper Montclair, NJ; M. Parker, Santa Barbara, CA; J. Pietz, Erftstadts, Germany; G. Poyner, Birmingham, England; R. Raphael, S.W. Harbor, ME; R. Royer, Lakewood, CA; P. Schmeer, Bischmisheim, Germany; C. Stephan, Sebring, FL; R. Stewart, Fairlawn, NJ; L. Szentasko, Budapest, Hungary; T. Vanmunster, Landen, Belgium; M. Verdenet, Bourbon-Lancy, France; M. Westlund, Uppsala, Sweden; D. York, Abiquiu, New Mexico. FADING OF 1904+43 MV LYRAE The novalike cataclysmic variable MV Lyr, which had been in its bright state at a mean magnitude of 12.5 since November 1989, has been fading since February, 1995, and is now oscillating at minimum, as indicated by the following observations: Feb 1.0, 12.7, L. Szentasko, Budapest, Hungary; 9.147, <12.5, M. Moeller, Timmendorfer Strand, Germany; 18.182, 12.8, G. Poyner, Birmingham, England; 24.0, 13.0, Szentasko; 28.0, 13.0, Szentasko; Mar 9.1, <14.0, S. Brincat, Floriana, Malta; 10.116, <13.7, A. Diepvens, Scheps, Belgium; 12.112, 15.3, Poyner; 12.18, 14.8, M. Verdenet, Bourbon-Lancy, France; 13.17, 14.8, Verdenet; 21.998, <14.2, Diepvens; Apr 22.0138, 16.0, Szentasko; 29.052, 14.0, Szentasko; May 1.026, 14.5, Poyner; 3.2097, 14.8, D. York, Abiquiu, NM. Accompanying is an "e" scale AAVSO Preliminary chart of MV Lyr. Please use this chart in monitoring MV Lyr during its faint state, and report your observations to AAVSO Headquarters. ERRATUM In AAVSO Alert Notice 206, the date of the last minor brightening of GK Per should have read July 1992. We apologize for this error. 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. We also encourage observers to send observations by fax at 617-354-0665 or by e-mail through the Internet at aavso@cfa.harvard.edu. When telephoning in observations, please state the name of the star, the magnitude, and the time of the observation. The preferred time is either your local time (be sure to state the time zone and whether it is Standard or Daylight Savings Time) or Universal Time. You do not need to give the designation of the star. Please also include the comparison stars you have used in making the observation. Many thanks for your efforts and your valuable observations. Good observing! Janet A. Mattei Director