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IAUC 5610: GRO J0422+32; FG Sge

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                                                  Circular No. 5610
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

GRO J0422+32
     G. Beskin and S. I. Neizvestny, Special Astrophysical Observatory;
and C. Bartolini, A. Guarnieri, and A. Piccioni, University
of Bologna, report:  "Spectroscopic and photometric observations of
GRO J0422+32 at the 6-m telescope show considerable variations of
the continuum in the ultraviolet region on a timescale of days.  In
some spectra, H-beta is seen as a broad absorption with a small
emission at its center.  Apparently there are several absorption
systems in the ranges 380-420 and 460-490 nm.  An emission line at
521.8 +/- 0.2 nm, possibly due to Fe II, is present.  The object
becomes strongly 'violet' with a practically synchronous brightness
increase in U, B, V, and R bands, the U brightness increasing much
more than the B.  On Sept. 5.918 UT, V = 13.37 +/- 0.01, U-B =
-0.40 +/- 0.02, B-V = +0.15 +/- 0.01, V-R = +0.53 +/- 0.01.  Fast
photometry reveals sporadic variability in the B and R bands, in
the form of short flashes of timescale 0.2-0.5 s, and relatively
smooth variations of duration 10-30 s.  Amplitudes of both
variations are 10-50 percent."

     R. Gonzalez-Riestra, International Ultraviolet Explorer (IUE)
Observatory, European Space Agency; and H. E. Jorgensen and C.
Grunnet, Copenhagen University Observatory, communicate:  "Because
of the pronounced drop in the visual brightness of FG Sge during
the last few weeks (IAUC 5604, 5609), observations of this star
were made with the IUE on Sept. 11.6 UT with the long-wavelength
spectrograph (195.0-335.0 nm) in the low-dispersion mode (resolution
0.6 nm).  The visual magnitude, as measured with the IUE Fine
Error Sensor, was about 11.1.  The observed flux in the range
270.0-330.0 nm was 2.90 x 10E-12 erg cmE-2 sE-1, a factor of 3.8
fainter than in the last observations performed in 1991 October,
indicating a decrease similar to that seen in the optical.  FG Sge
is now at the lowest level since it started to be regularly observed
with IUE in 1982.  The overall spectral shape appears not to
be varying.  The shape and strength of the Fe II multiplet uv1 near
263.0 nm has varied in a complex way and appears weaker.  Infrared
observations are needed in order to clarify the origin of the
decline in brightness."
     Further visual magnitude estimates:  Sept. 10.9 UT, 11.0 (J.
Speil, Walbrzych, Poland); 11.98, 11.0 (B. H. Granslo, Fjellhamar,
Norway); 13.31, 10.8 (R. Royer, Lakewood, CA); 14.19, 11.4 (D.
York, Abiquiu, NM).

1992 September 14              (5610)            Daniel W. E. Green

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