Central Bureau for Astronomical Telegrams
IAUC 7002: SGR 1900+14; V592 Her
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Circular No. 7002
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SGR 1900+14
T. L. Cline, Goddard Space Flight Center (GSFC); and E. P.
Mazets and S. V. Golenetskii, Ioffe Physical-Technical Institute,
St. Petersburg, write: "A > 50-keV transient of intensity
comparable to a strong gamma-ray burst triggered the GRB monitor on
the Global Geo-Science Wind spacecraft on Aug. 27.432148 UT,
exhibiting a persistent periodicity of 5.15 +/- 0.02 s. This is
the first gamma-ray transient seen to clearly exhibit a periodic
response in an uncollimated GRB detector since the 1979 March 5
event, itself the progenitor of the first known soft gamma-ray
repeater (SGR). This transient is assumed to originate from SGR
1900+14, in view of its current state of activity (see, e.g., IAUC
6929), although there is no directional information from the Konus
instruments other than a north-ecliptic-hemisphere indication,
consistent with SGR 1900+14. Since the GGS-Wind spacecraft is not
in a near-earth orbit, comparison with other observations may be
able to provide a source directional annulus and confirmation of
this identity."
R. Remillard, D. A. Smith, and A. Levine, Massachusetts
Institute of Technology (MIT), report on behalf of the RXTE/ASM
teams at MIT and at NASA/GSFC: "The RXTE All Sky Monitor has
detected an x-ray flare at a location consistent (+/- 0o.2 deg)
with the position of the candidate x-ray counterpart for SGR
1900+14 (Hurley et al. 1996, Ap.J. 463, L13). Two consecutive
detections were made in each of two cameras on Aug. 27, showing a
2-12-keV intensity of 78 +/- 12 mCrab at Aug. 27.5174 UT and 114
+/- 11 mCrab at Aug. 27.5185. During the preceeding week, there
were no significant detections made, and on Aug. 26, the average of
13 measurements implies a 3-sigma upper limit of 14 mCrab. On the
day following the flare, seven measurements indicate a mean
intensity 18 +/- 5 mCrab. During all of the 90-s exposures
associated with ASM detections, the time-series data indicate
steady emission with no evidence of SGR bursts."
V592 HERCULIS
E. O. Waagen, AAVSO, reports that this 'tremendous outburst
amplitude dwarf nova' (cf. Howell et al. 1995, Ap.J. 439, 337) is
in outburst for only the third time since 1968, as indicated by the
following visual magnitude estimates: Aug 24.901 UT, [15.3 (G.
Poyner, Birmingham, England); 25.90, [13.2 (P. Schmeer,
Bischmisheim, Germany); 26.835, 12.0 (T. Kinnunen, Espoo, Finland);
27.181, 13.0 (L. Shaw, Pinole, CA); 27.192, 13.0 (G. Hanson, Cave
Creek, AZ); 28.051, 13.5 (J. Bortle, Stormville, NY); 28.233, 12.9
(Shaw).
(C) Copyright 1998 CBAT
1998 August 30 (7002) Daniel W. E. Green
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