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IAUC 5676: GRO J0422+32; GRO J1837+59

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                                                  Circular No. 5676
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)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)


GRO J0422+32
     T. Kato, S. Mineshige, and R. Hirata, Kyoto University, write:
"CCD photometry of the optical counterpart of GRO J0422+32 was
obtained with the 0.6-m telescope at Ouda Station, Kyoto University,
on five nights during Nov. 21-25.  The analysis of the data reveals
periodic modulation with a period of 0.217 +/- 0.001 day and an
amplitude of 0.10 mag in V.  The light curve exhibits a steeper
rise than decline and resembles superhumps in SU UMa-type stars.
The secondary humps are not detected.  The considerable increase in
amplitude and the distinct light curve profile from that reported
by Chevalier and Ilovaisky (IAUC 5644) suggest that the present
modulation may have developed after their observations.  If this
modulation is caused by the tidal instability of the accretion disk,
as in SU UMa stars, and with an assumption of the Roche lobe-filling
main sequence secondary, the lower limit of the mass of the compact
object is 2.2 solar masses, which exceeds the 1.4 solar mass
of the canonical neutron star (Mineshige et al. 1992, Publ. Astron.
Soc. Japan, 44, L15-18)."


GRO J1837+59
     The Compton Observatory EGRET Team (Y. C. Lin, J. Chiang, J.
Fierro, P. F. Michelson, and P. L. Nolan, Stanford University; K.
Brazier, G. Kanbach, H. A. Mayer-Hasselwander, and C. von Montigny,
Max-Planck-Institut fur Extraterrestrische Physik; D. L. Bertsch,
B. L. Dingus, C. E. Fichtel, R. C. Hartman, S. D. Hunter, P. W.
Kwok, J. R. Mattox, P. Sreekumar, and D. J. Thompson, Goddard Space
Flight Center, NASA; D. A. Kniffen, Hampden-Sydney College; and E.
Schneid, Grumman Aerospace Corporation) communicates:  "Quick-look
analysis of EGRET high-energy gamma-ray data for the current
Compton Observatory pointing shows a bright source (designated GRO
J1837+59) coincident with one seen in the observation of 1991 May
30-June 8.  The best estimate of the source position is l = 88.7
deg, b = +24.8 deg, with a 68-percent-confidence error radius of
0.4 deg. The positional uncertainty is relatively large due to the
large angle of the source from the detector axis.  No catalogued
sources at other wavelengths are obvious counterparts of the gamma-
ray source.  The present Compton Observatory viewing continues
until Dec. 22, and a more sensitive observation of this source
region is scheduled for 1993 Mar. 9-23."


1992 December 16               (5676)            Daniel W. E. Green

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