Central Bureau for Astronomical Telegrams
IAUC 5842: GRO J0422+32; 1993R
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Circular No. 5842
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)
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MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
GRO J0422+32
A. V. Filippenko and T. Matheson, University of California,
Berkeley, report that the brightness of GRO J0422+32 appears to have
increased significantly since the last reports in April (cf. IAUC
5761, 5764). Preliminary calibration of spectra (range 310-1000 nm)
obtained on Aug. 13 UT with the Shane 3-m reflector at Lick Observatory
yields V = 14.7 +/- 0.5. Strong, broad Balmer absorption lines are
visible in the rather blue continuum; H-alpha exhibits an emission
component, as well. The object may have experienced a new accretion
event at some time during the past four months.
A. J. Castro-Tirado, Danish Space Research Institute, Lyngby; and
J. L. Ortiz, Instituto de Astrofisica de Andalucia, Granada, report:
"We have been observing the optical counterpart of the soft x-ray
transient GRO J0422+32, discovered in 1992 Aug. (cf. IAUC 5580, 5588,
5597). CCD frames taken at the Spanish 1.52-m telescope at the
German-Spanish Calar Alto Observatory have shown that GRO J0422+32 has
undergone a dramatic and unexpected increase in brightness by 3.6 mag
in the last three days. Preliminary magnitudes (+/- 0.2): Aug. 10.105
UT, V = 18.7; 13.17, 15.1. The object may be emitting strongly at high
energies, therefore x-rays and gamma-ray observations should be very
valuable. Spectroscopic and photometric observations at all wavelengths
are encouraged."
SUPERNOVA 1993R IN NGC 7742
Filippenko and Matheson also report: "Careful inspection of
fully calibrated spectra (range 310-1020 nm) obtained on June 28,
July 14, and July 28 UT with the Shane 3-m reflector suggests that
SN 1993R (cf. IAUC 5812) is a peculiar type-I supernova, rather than
type II as stated on IAUC 5818. The line previously attributed to
H-alpha is seen in type-Ia supernovae, and is generally thought to
be [Fe II]. However, in other respects there are substantial
differences from the late-time (nebular) spectra of normal type-Ia
supernovae. The spectrum of SN 1993R bears some resemblance to
that of the peculiar, subluminous type-Ia SN 1991bg, but the Ca II
near-infrared triplet is strong in the former and very weak in the
latter. The main difference from the nebular spectra of type-Ib
and -Ic supernovae is that the [O I] 630-nm emission is weak in SN
1993R. The absolute R magnitude of SN 1993R at the time of
discovery (probably near maximum brightness) was only -16 +/- 1 for
H0 = 50 km/s/Mpc. Note that the object is superposed on a very
bright H II region."
1993 August 13 (5842) Daniel W. E. Green
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