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IAUC 5704: GRO J0422+32; P/SCHWASSMANN-WACHMANN 1; N Cyg 1992

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IAUC number

                                                  Circular No. 5704
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
     T. Kato, S. Mineshige, and R. Hirata, Kyoto University, write:
"V-band CCD photometry of the optical counterpart of GRO J0422+32
was obtained with the 0.6-m telescope at Ouda Station, Kyoto
University, on 14 nights between 1992 Dec. 13 and 1993 Jan. 12.
Analysis of the data reveals the appearance of a periodicity other than
that reported on IAUC 5676.  The present light curve is characterized
by roughly sinusoidal variation (amplitude 0.2 mag) and dips.
The sinusoidal variation and dips are excellently expressed by a
single period 0.2122 +/- 0.0001 day.  The dips occur exactly at
phase 0.44 after the minima of the sinusoidal variation and have
typical duration of an hour and an amplitude of 0.1 mag, though
varying from 0.05 mag at Jan. 1.52 to 0.17 mag at Jan. 12.58 UT.
The firm periodicity and the sharp profile suggest an eclipse origin
of the dips.  The proposed orbital period (0.2122 day) shows a
marked difference from the photometric periodicity of 0.217 day
reported on IAUC 5676.  The latter is 2.2 +/- 0.5 percent longer than
the orbital one, thus confirming the superhump nature of the transient
periodicity observed in Nov.  We suggest that the most probable
range of the mass of the compact object is between 2.9 and 6.2
solar masses, following the scheme denoted on IAUC 5676."

     S. Nakano, Sumoto, Japan, forwards a report from T. Kojima
(Chiyoda, Gunma Ken) that this comet is again in outburst.  A
photograph taken with a 0.25-m f/3.4 Wright Schmidt telescope on Jan.
29.53 UT shows the comet at mag 14, being diffuse with strong central
condensation, the coma extending to the north in a manner suggesting
that the outburst is two or three days old.  Other recent
total visual magnitude estimates (cf. IAUC 5674, 5675):  1992 Dec.
17.60 UT, 14.1 (A. Nakamura, Kuma, Japan, 0.60-m reflector); 25.52,
14.1 (Nakamura); 29.96, 14.5 (H. Mikuz, Ljubljana, Slovenia, 0.20-m
reflector + CCD + V filter); 31.00, 14.6 (Mikuz).

     Visual magnitude estimates:  1992 Dec. 23.72 UT, 10.0 (A.
Lauvstad, Levanger, Norway); 1993 Jan. 1.78, 10.0 (P. Schmeer,
Bischmisheim, Germany); 15.09, 10.3 (B. H. Granslo, Fjellhamar,
Norway); 22.04, 10.5 (W. G. Dillon, Missouri City, TX); Feb. 3.76,
10.5 (Schmeer).

1993 February 4                (5704)            Daniel W. E. Green

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