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IAUC 5875: SGR 1806-20; PLUTO; N Sgr 1993

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IAUC number

                                                  Circular No. 5875
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

SGR 1806-20
     C. Kouveliotou, J. M. Horack, G. J. Fishman, C. A. Meegan, and
W. S. Paciesas report for the BATSE Team:  "We have detected
repeated soft gamma-ray emission from a region centered at R.A. =
18h16m, Decl. = -20o with an average error radius of about 6 deg.
Three triggers were recorded on Sept. 29.40280, 29.85163, and
29.96912 UT.  All triggers are similar; each consists of a single
pulse of duration about 75, 200, and 40 ms at full width zero
amplitude, respectively.  Their spectra are consistent with a typical
Soft Gamma Repeater (SGR) spectrum; no emission is detected above
100 keV.  Our results are consistent with the location of the SGR
1806-20 (Atteia et al. 1987, Ap.J. 320, L105).  The high frequency
of the triggers (three in about 14 hr) is consistent with the
emission pattern of this source, which is known to emit multiple
episodes per day (Laros et al. 1987, Ap.J. 320, L111).  Our results
indicate that SGR 1806-20 has become active again.  Follow-up
observations of the source region at other wavelengths are strongly

     A. Gilmore and P. Kilmartin, Mount John University Observatory,
report that observations of star P20, Pluto, and Charon, were made
during Oct. 3.358-3.386 UT with the 0.6-m f/13 Cassegrain reflector
(+ single channel photometer No. 1 + Cousins R filter + 30"
aperture), revealing no occultation by Charon (cf. IAUC 5872).  Every
2-3 min, integrations were interrupted for 5-10 s to check tracking.
There was thin cirrus near the region and possibly over it.  The
net count rate was about 100 Hz at the start and declined to about
50 Hz at the end of observation; no changes occurred in count rate
other than those attributable to the increasing air mass (to > 6
air masses).  An integration time of 0.5 s was used because of the
low rate.

     Visual magnitude estimates (cf. IAUC 5868):  Sept. 23.12 UT,
9.1 (R. Royer, Lakewood, CA); 23.72, 9.1 (D. Overbeek, Edenvale, S.
Africa); 25.83, 8.7 (A. Pereira, Cabo da Roca, Portugal); 26.41,
9.5 (A. F. Jones, Nelson, New Zealand); 26.83, 9.4 (Pereira); 27.41,
9.1 (Jones); 27.82, 9.6 (Pereira); 28.37, 9.2 (Jones); Oct. 3.83,
10.3 (Pereira).

1993 October 5                 (5875)            Daniel W. E. Green

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