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Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
We would like to submit following article to IAUC.
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 Dec. 13, 1992 and Jan. 12, 1993. The analysis
of the data reveals appearance of another periodicity other than
reported in IAUC 5676. The present light curve is charaterized 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 exactly occur at phase 0.44 after the
minima of the sinusoidal variation and have typical duraion of an hour
and an amplitude of 0.1 mag, but is varying from 0.05 mag at Jan. 1.52 UT
to 0.17 mag at Jan. 12.58 UT. The firm periodicity and the sharp profile
suggest the eclipse origin of the dips. The proposed orbital period
(0.2122 day) shows marked difference from the photometric periodicity
of 0.217 day reported in IAUC 5676. The latter is 2.2 +/- 0.5 % longer
than the orbital one, thus confirming the superhump nature of the transient
periodicity observed in Nov. We suggest the most probable range of the
mass of the compact object between 2.9 and 6.2 solar masses following
the scheme denoted in IAUC 5676."
Jan. 19, 1993
Taichi Kato
Shin Mineshige
Ryuko Hirata
Department of Astronomy, Faculty of Science, Kyoto University
e-mail: tkato@kusastro.kyoto-u.ac.jp
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