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IAUC 6075: 2S 1417-624; X-RAY N IN Sco; 1994o

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                                                  Circular No. 6075
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

2S 1417-624
     C. A. Wilson and R. B. Wilson, Marshall Space Flight Center,
NASA; M. H. Finger and S. N. Zhang, University Space Research
Association; and D. Chakrabarty and T. A. Prince, California
Institute of Technology, report for the Compton Observatory BATSE
Team: "An outburst of the transient x-ray binary pulsar 2S 1417-624
is currently being observed.  Pulsations in the energy band 20-50
keV were first detected on Aug. 26 at a frequency consistent with
the discovery observation of this source (Kelley et al. 1981, Ap.J.
243, 251).  On Sept. 4-5, the source was detected between 20 and 70
keV with a phase-averaged pulsed flux of 10 +/- 2 mCrab and a total
flux of 75 +/- 15 mCrab.  The pulse phases between Aug. 26 and Sept.
6 are consistent with a barycentric pulse frequency of 5.666395(5)
x 10E-2 Hz on Aug. 31.0 UT, with a frequency derivative of 2.936(9)
x 10E-11 Hz/s.  A search of the 20- to 50-keV BATSE data from 1991
April to date revealed no previous outbursts.  Optical observations
of the proposed Be-star companion (Grindlay et al. 1984, Ap.J. 276,
621) are encouraged."

     W. S. Paciesas, S. N. Zhang, C. A. Wilson, and B. A. Harmon
report for the Compton Gamma Ray Observatory BATSE team:  "We have
detected a second outburst of this object (GRO J1655-40), beginning
on Sept. 6.  The hard x-ray (20-100 keV) flux from this source had
declined rapidly from about 700 to about 150 mCrab over a few-day
period beginning about Aug. 12 and remained at or below that level
through Sept. 5.  Our preliminary flux estimates for Sept. 6 and 7
are 440 +/- 50 and 370 +/- 30 mCrab, respectively.  The rapid
decline of the first x-ray outburst coincides well with the
calculated emission time of the expanding radio lobe (IAUC 6073).
The reflare may portend further interesting radio and/or optical

     Further total visual magnitude estimates:  Sept. 2.36 UT, 7.0
(J. E. Bortle, Stormville, NY, 10x50 binoculars); 5.12, 6.8 (H.
Mikuz, Cres, Croatia, 7x50 binoculars; faint tail about 1 deg long
in p.a. 310 deg); 6.11, 7.2 (Mikuz); 7.48, 7.3 (C. S. Morris, near
Mt. Wilson, CA, 20x80 binoculars).

1994 September 9               (6075)            Daniel W. E. Green

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