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IAUC 6468: SMC X-1; N Cru 1996; V635 Cas; C/1995 O1

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                                                  Circular No. 6468
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
Phone 617-495-7244/7440/7444 (for emergency use only)

     S. N. Zhang, C. R. Robinson, R. B. Wilson, B. A. Harmon, and
D. M. Scott, on behalf of the BATSE/CGRO team; and R. Remillard, on
behalf of the ASM/RXTE team, report: "Quasiperiodic flux variations
have been observed from the 0.7-s pulsar SMC X-1 with a period
around 60 days, in the energy bands 1.3-12 keV (ASM/RXTE) and
20-100 keV (BATSE/CGRO), confirming the HEAO-1 results in 1977-1978
(Gruber and Rothschild 1984, Ap.J. 283, 546).  A sequence of five
outbursts between early Oct. 1995 and mid-Aug. 1996 is apparent in
the BATSE/CGRO lightcurve, of which the last three coincide with
those observed from ASM/RXTE (the first two of the three ASM
outbursts have been reported by Levine et al. 1996, Ap.J. 469, L33).
The peak flux is about 30 mCrab in both bands.  No significant
outbursts were observed in the BATSE data between Apr. 1991 and Oct.
1995, though a weak level of emission at about 10-20 mCrab was
sometimes detected.  Eclipses with a duration of about 20 percent
of the orbital period of 3.9 days are observed in both data sets.
The current outburst was detected about Aug. 27."

     Precise position from G. J. Garradd, Loomberah, N.S.W.,
obtained on Sept. 3.409 UT (0.25-m f/4.1 reflector + CCD):  R.A. =
12h10m31s.40, Decl. = -61 45'09".6 (equinox 2000.0), mag R = 9.9.

     G. M. Hurst, The Astronomer, reports that G. Poyner
(Birmingham, U.K.) observed a short-lived visual outburst of V635
Cas (= 4U 0115+634) occurring some days after the detection of the
reported hard-x-ray flux on Aug. 10 (IAUC 6450), as indicated by
the following magnitude estimates:  Aug. 8.008 UT, 15.0; 11.956,
15.1; 17.027, 14.7; 18.991, 14.3; 21.979, 14.3; 25.897, 14.6.

     K. Jockers, T. Credner, N. Karpov, and A. Sergeev report that,
using the 2-m telescope (+ 2-channel focal reducer of the Max
Planck Institute for Aeronomy, Katlenburg-Lindau) of the Centre
AMEI, Kiev, at Mount Terskol, they observed the ejection of a CO+
cloud into p.a. 130 deg on Aug. 17.8 UT.  On the following nights,
the CO+ tail gradually subsided.

                      (C) Copyright 1996 CBAT
1996 September 3               (6468)            Daniel W. E. Green

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