THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS 25 Birch Street, Cambridge, MA 02138 USA INTERNET: firstname.lastname@example.org Tel. 617-354-0484 FAX 617-354-0665 AAVSO ALERT NOTICE 214 (October 3, 1995) 0557-23 SUPERNOVA 1995ad IN NGC 2139 We have been informed by the Central Bureau for Astronomical Telegrams (IAU Circular 6239) and R. McNaught, Anglo-Australian Observatory, of the visual discovery of a supernova in NGC 2139 by the Rev. Robert O. Evans, Coonabarabran, NSW, Australia, on Sep 28.8 UT at magnitude 14-14.5. The discovery was confirmed by McNaught on Sep 29.8, using the 1.0-m telescope +CCD at Siding Spring. Evans reported no image visible on Aug 25 with his 0.41-m reflector (IAU Circular 6239). The supernova is located 25" west and 5" south of the nucleus of NGC 2139, whose (2000) position is: R.A. 06h 01.1m Dec = -23 degrees 40' Spectroscopic confirmation was obtained by S. Benetti, European Southern Observatory, and D. Grupe, Universitats-Sternwarte, Gottingen, who reported that a fully-reduced CCD spectrogram (range 390-784 nm, resolution 0.4 nm) taken with the ESO 1.5-m telescope (+ Boller & Chivens spectrograph) at La Silla, Chile, on Sep 29.30 UT shows the object to be a type-II supernova around maximum (IAU Circular 6239). Please use the accompanying CCD (R) image provided by S. Benetti, ESO in observing 0557-23 SN 2139. Please report your observations in letter sequence, using the letters we have added to the comparison stars, and assigning 10 steps between each comparison star. Congratulations to Bob Evans on his latest discovery! 0059+53 NOVA CASSIOPEIAE 1995 The slow nova, N Cas 95 (see AAVSO Alert Notice 213), continues to be bright, as the observations in the accompanying light curve show. Our thanks to all observers who have been observing this very interesting nova and reporting their observations to AAVSO Headquarters. The optical behavior of Nova Cas 1995 appears to be similar to the early stages of the slow nova HR Delphini (Nova Del 1967), as is indicated by the accompanying light curve from the AAVSO archives. HR Del also took about a month to brighten from 12th to 6th magnitude, rose by another magnitude, and then stayed bright with fluctuations for about four months until it brightened by several magnitudes again. Accompanying is a revised AAVSO preliminary "b" scale chart, prepared by C. Scovil using the photoelectric (V) sequence provided by B. Skiff, Lowell Observatory (via vsnet), and from the Hipparcos Input Catalogue. Please use this chart to observe N Cas 95. When you report your observations to AAVSO Headquarters, please be sure to indicate which chart and which comparison stars you used to make your estimates. OBSERVATIONS OF 0409-71 VW HYDRI AND 0749+22 U GEM Astronomers at Villanova University will be observing the dwarf novae VW Hyi and U Gem with the Hubble Space Telescope later this month, U Gem on October 10 and VW Hyi on October 21. We have been requested to monitor these two stars and inform the astronomers of their status. Please monitor these two stars nightly and call, fax, or email your observations to AAVSO Headquarters daily, through October 15 for U Gem and through October 24 for VW Hyi. Our assistance is EXTREMELY important to the success of these observing runs. FADING OF 1544+28A R CORONAE BOREALIS R CrB, the prototype of the R CrB class of variables, appears to be fading, as the following observations indicate: Sep 25.1125 UT, 6.1, W. Dillon, Missouri City, TX; 27.001, 6.1, F. West, Hanover, PA; 28.008, 6.1, West; 28.0972, 6.1, Dillon; 29.002, 6.0, West; 29.9882, 6.0, P. Dombrowski, Glastonbury, CT; 30.0708, 6.3, C. Stephan, Sebring, FL; Oct 1.028, 6.1, West; 1.74, 6.2, G. Zajacz, Debrecen, Hungary; 1.86, 6.1, G. Poyner, Birmingham, England; 1.900, 6.3, Poyner; 1.926, 6.5, Poyner; 2.000, 6.3, Dombrowski; 2.9888, 6.6, Dombrowski; 3.0000, 6.6, Bortle; 3.006, 6.2, West; 3.0910, 6.9, D. York, Abiquiu, NM. The last fading of R CrB occurred in August 1993 - January 1994, when the star reached magnitude 8.5 at minimum. Fadings of R CrB are unpredictable both in duration and in the magnitude to which the star may fade. Observers are urged to keep a close eye on R CrB, and to report their observations to Headquarters until the star returns to maximum at around 6.0. CHANGE OF JULIAN DATE TO 2450000 and AAVSO DATA ENTRY PROGRAM Observers are alerted to the fact that the third digit of the Julian Day will be changing to "5" on October 9. October 9, 1995, will be JD 2450000. A change of this order occurs only every 27.39 years! For those observers who use the AAVSO-distributed data entry program to enter their observations and prepare their monthly report, the version of the program you have assumes the JD to be 244..... We will be distributing a substantially revised version of the data entry program in mid-October to all observers to whom we have sent the data-entry and report-formatting software in the past. The revised program accommodates any JD, and is much more flexible and user-friendly. If you have not received data-entry software from us in the past, please let us know if you would like to receive the AAVSO's data-entry and report-formatting software (which allows you to enter your observations in any order and in any number of files, and to prepare a monthly report in AAVSO format); please indicate if you need a 3.5- or 5.25-inch diskette. CHARTS AND LIGHT CURVES AVAILABLE ON AAVSO FTP SITE We have prepared electronic copies of AAVSO charts and light curves mentioned in this Alert Notice for the following stars: SN 1995ad in NGC 2139 (chart), N Cas 95 (chart and light curve), HR Del (light curve). They are available from our FTP site: ftp.aavso.org (184.108.40.206), in /pub/alert214 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 to 617-354-0665 or by e-mail through the Internet to email@example.com. Many thanks for your significant astronomical observations and efforts. Good observing! Janet A. Mattei Director Caption for the CCD image: SN 1995ad in NGC 2139. CCD(R) image obtained by S. Benetti, European Southern Observatory, using 3.6m telescope, on 1995, October 2. The field of view is 5.2 X 5.2 arcminutes. Courtesy of S. Benetti, ESO. Contributors to AAVSO light curve of N Cas 1995: T. Bakonyi, Sandro Baroni, Terry Benner, John Bortle, Mark Bradbury, Eric Broens, John Brooks, Thomas Burrows, Glenn Chaple, Richard Campbell, Michael Collins (via G.Hurst, novanet, IAUC 6214), J. Csanyi, Roger Diethelm, Albert Dill, William Dillon, Mary Dombrowski, Philip Dombrowski, Gerald Dyck, Robert Fidrich, John Griese, Timothy Hager, Edward Halbach, Peter Hallett, James Hannon, Robert Hays, Lawrence Hazel, Richard Huziak, Robert King, Laszlo Kiss, K. Kosaka (via O. Ohshima, novanet, IAUC 6214), Thomas Lubbers, Jerome McKenna, Attila Mizser, Robert Modic, Jack Nordby, John O'Neill, Laszlo Osvald, Alfredo Pereira, Gary Poyner, Francisco Pujol, Jose Ripero Osorio, Phillip Robbins, Diego Rodriguez, George Rosenberg, Ronald Royer, Sei-ichi Sakuma, J. Sanjuan, Patrick Schmeer, Charles Scovil, Neil Simmons, Christopher Spratt, Christopher Stephan, Robert Stewart, Gyorgi Szabo, Gyula Szabo, Rita Szabo, Robert Szabo, P. Szakal, Laszlo Szentasko, Henri Van Bemmel, Wolfgang Vollmann, Gary Walker, Paul Walker, M. Yamamoto (via vsnet, IAUC 6213), Robert Young, Z. Zakany, Mauro Zanotta, Ronald Zissell.