Circular No. 4783 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Telephone 617-495-7244/7440/7444 (for emergency use only) TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505 MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN V404 CYGNI = GS 2023+338 Following a suggestion by the undersigned that the x-ray nova GS 2023+338 might be identical with V404 Cyg, a mag 12.5 optical nova in 1938 that Duerbeck (1987, A Reference Catalogue and Atlas of Galactic Novae) has identified with a mag 20.5 object on the Palomar Sky Survey at R.A. = 20 22 06.26, Decl. = +33 42'18".3 (equinox 1950.0) and that is located only 5' outside the Ginga error box (IAUC 4782), V404 Cyg was observed by R. M. Wagner, Ohio State University; S. G. Starrfield, Arizona State University; and A. Cassatella, IUE Vilspa, who report: "Visual inspection with the Perkins 1.8-m telescope at the Lowell Observatory on May 26.4 UT revealed the object on Duerbeck's finding chart at mag 12-13. Photometry with the fine-error sensor on the IUE satellite on May 27.3 gave V about 12.6. Initial spectra obtained with IUE were unsuccessful due to the faintness of V404 Cyg in the ultraviolet part of the spectrum. Optical spectra were obtained on May 27.4 using the Perkins telescope and Ohio State University CCD spectrograph. The spectra (range 320-1000 nm, resolution about 1 nm) exhibited strong emission lines superposed on a reddened continuum. Emission lines identified included Balmer and Paschen series lines; He I 587.6, 667.8 and 706.5 nm; He II 468.6 nm; the C III/N III blend at 464.0 nm; and possibly weak Fe II. He II 468.6 was comparable in strength to H beta. No absorption lines or forbidden lines were detected. Based on these preliminary observations, it is highly probable that V404 Cyg is the optical counterpart of the x-ray source." G. M. Hurst, Basingstoke, England, reports that M. Mobberley, Chelmsford, obtained a 10-min exposure of the GS 2023+338 area on May 26.99 UT, and Hurst confirms from this that V404 Cyg was recorded in outburst at mpv about 12.5. He adds that the star is not present on the following charts: Lick Atlas (1954 Aug. 31, B [ 15), Atlas Stellarum (1967 Sept. 2, B [ 14) and Papadopoulos (1976 July 25, pv [13). AM HERCULIS Visual magnitude estimates: Jan. 4.20 UT, 12.8 (S. Korth, Dusseldorf, West Germany); Mar. 31.39, 12.9 (P. Sventek, Houston, TX); May 1.91, 12.5 (M. Verdenet, Bourbon-Lancy, France); 2.89, 13.0 (Verdenet); 2.96, 14.2 (R. Monella, Covo, Italy); 5.97, 13.4 (A. Boattini, Florence, Italy); 8.95, 14.2 (Monella); 21.93, 14.6 (Korth); 22.95, 14.9 (Korth); 23.83, 13.7 (Boattini); 23.93, 15.6 (Korth); 24.87, 13.8 (Boattini). 1989 May 27 (4783) Brian G. Marsden
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