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IAUC 4783: V404 Cyg = GS 2023+338; AM Her

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                                                  Circular No. 4783
Central Bureau for Astronomical Telegrams
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

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).

     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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