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 245 (March 23, 1998) 1815-27 NOVA SAGITTARII 1998 We have been informed by William (Bill) Liller, Vina del Mar, Chile and by the Central Bureau for Astronomical Telegrams (IAU Circular 6846) of the discovery by W. Liller, using the PROBLICOM method, of a nova in Sagittarius at magnitude 7.8 on photographs taken on March 22.3628, 22.3642 and 22.3663 UT. The discovery photographs were taken with Technical Pan film and an orange filter. Liller's CCD observation with broad V filter of the nova on March 23.316 UT showed it to be at magnitude 7.74. Nothing brighter than magnitude 11.5 appeared on two photographs taken on March 18.35. S. Nakano, Sumoto, Japan forwards the following position from Y. Kushida, Yatsugatake South Base Observatory from an image obtained on March 23.771 UT using a 0.40-m reflector (IAU Circular 6847): R.A. = 18h21m40s.47 , Decl. = -27o31'38".0 (equinox 2000) The closest star present in the USNO A1.0 catalogue (and on the Digital Sky Survey) is one of approximate magnitude 17 located 6".5 north of the nova. (IAU Circular 6847) Liller also reports that a low resolution spectrogram of N Sgr 98, obtained with a 0.20-m Schmidt camera (+ objective prism + CCD) on March 23 UT, shows H-alpha emission approximately 1.5 times brighter than the surrounding continuum. Further magnitude estimates reported to the Central Bureau for Astronomical Telegrams(IAU Circ. 6847) are as follows: March 23.682 UT, 8.2 CCD-unfiltered (G. J. Garradd, Loomberah, N.S.W.); 23.724, 7.8 (M. Aoki, Toyama, Japan); 23.771, 8.1 (Y. Kushida, Yatsugatake South Base Observatory, Japan). Accompanying is a finder chart for N Sgr 98 which was provided by W. Liller and made using Project Pluto's Guide 6.0. V magnitudes from the Hipparcos and Tycho Catalogues are indicated for the two comparison stars used by Liller. Please use this chart to observe the nova until the AAVSO preliminary chart (currently being prepared by C. Scovil) becomes available*, and report your observations of 1815-27 N Sgr 98 to AAVSO Headquarters, making sure to indicate which comparison stars you used. Congratulations to Bill on his latest discovery! CHARTS AVAILABLE ON AAVSO FTP SITE Electronic copies of the finder chart for N Sgr 98 mentioned in this Alert Notice are available from our FTP site: ftp.aavso.org (18.104.22.168), in /pub/alerts/alert245 The chart 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. 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 valuable astronomical contributions and your efforts. Good observing! Janet A. Mattei Director * An AAVSO 'b' scale preliminary chart of WW Sgr on which Nova Sgr 1998 appears has been prepared and is attached (March 24, 1998).