IAUC 6586 Excerpt: GS1843+00
Circular No. 6586
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
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Excerpt:
GS 1843+00
R. B. Wilson and B. A. Harmon, Marshall Space Flight Center,
NASA; D. M. Scott, M. H. Finger, and C. R. Robinson, Universities
Space Research Association; D. Chakrabarty, Massachusetts Institute
of Technology; and T. A. Prince, California Institute of Technology,
report for the Compton Observatory BATSE Team: "Pulsations from the
transient x-ray binary pulsar GS 1843+00 have been detected since
Mar. 3 in the energy range 20-50 keV. Using observations through
Mar. 9, the mean barycentric pulse frequency at epoch Mar. 6.0 UT
was (3.382592 +/- 0.000035) x 10E-2 Hz. The observed spinup rate
during this observation is (4.18 +/- 0.12) x 10E-11 Hz sE-1. The
mean RMS pulsed flux integrated over 20-50 keV was (3.75 +/- 0.24)
x 10E-10 erg cmE-2 sE-1 on Mar. 8-9. Earth-occultation
measurements indicate a steady increase in total intensity from
early March to Mar. 8-9, with a total flux of 5.1 +/- 0.5 x 10E-9
erg cmE-2 sE-1, giving a pulse fraction of about 7 percent. The
thermal bremsstrahlung model (without Gaunt factor) yields a
temperature of 23 keV. Pulsed and steady emission are also
observed on Mar. 10. Updates to source intensity and pulse
frequency are posted twice-weekly for this and all other bright
sources detected by BATSE at the web site http://www.gammaray.nsstc.nasa.gov.
Observations are encouraged at all wavelengths, as no optical
counterpart is currently known for this source."
(C) Copyright 1997 CBAT
1997 March 14 (6586) Daniel W. E. Green
Permission to post obtained from CBAT
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