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IAUC 6585: C/1995 O1; 1RXS J170849.0-400910

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                                                 Circular No. 6585
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)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


COMET C/1995 O1 (HALE-BOPP)
     H. Matsuo, A. Sakamoto, N. Kuno, and N. Ukita, Nobeyama Radio
Observatory; and T. Fuse, Graduate University for Advanced Studies,
report:  "Millimeter-wave continuum observations of comet C/1995 O1
at 150 GHz, with the Nobeyama 45-m telescope (+ seven-element
bolometer array) on Mar. 2.96 and 4.92 UT, yield detection of a
compact component with a flux density of 55 +/- 7 mJy.  We also
observed the comet on Mar. 5.92 at 100 GHz with a 4-beam SIS
receiver and measured the flux density as 29 +/- 4 mJy.  Lower-
frequency observations are highly desired for modelling the dust
spectrum of the comet."


1RXS J170849.0-400910
     M. Sugizaki and F. Nagase, Institute of Space and
Astronautical Science; S. Yamauchi, Iwate University; K. Koyama,
Kyoto University; K. Matsuzaki, University of Tokyo; T. Asanuma, K.
Kinugasa, and K. Torii, Osaka University; and T. Kotani, Riken,
communicate on behalf of the ASCA Galactic Ridge Survey Team:
"During the galactic ridge survey with ASCA, we detected a
relatively bright, soft source on 1996 Sept. 3.021-3.590 UT at R.A.
= 17h08m46s, Decl. = -40o09'27" (equinox 2000.0).  This source is
identified with the ROSAT source 1RXS J170849.0-400910 within the
ASCA position determination accuracy of radius 0'.5.  From timing
analysis of the source, we discovered coherent pulsations with a
barycentric pulse period P = 10.997 +/- 0.001 s.  The x-ray pulse
profile shows a broad sinusoidal shape with a pulse fraction of
about 30 percent.  The energy spectrum in the range 1-10 keV is
very soft and can be fitted by a power-law model with photon index
3.5 and an absorption column density 1.8 x 10E22 cmE-2.  The energy
spectrum can also be fitted with an optically thin thermal
bremsstrahlung model with kT = 1.8 keV, although no emission line
of iron is found with an upper limit of equivalent width 500 eV
(either for a 6.4-, 6.6-, or 6.9-keV line; 90-percent confidence
limit).  The pulse-phase averaged flux in the range 1-10 keV is
about 1.2 x 10E-10 cmE-2 sE-1 after correcting for soft x-ray
absorption.  From the 11-s period and the soft spectrum, we suspect
this source to be the sixth member of a class of braking x-ray
pulsars (Mereghetti and Stella 1995, Ap.J. 442, L17; van Paradijs
et al. 1995, A.Ap. 299, L41)."

                      (C) Copyright 1997 CBAT
1997 March 12                  (6585)            Daniel W. E. Green

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