Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 6835: 1998S, 1998T; AX J0049-729; IRAS 18325-5926

The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).

Read IAUC 6834 SEARCH Read IAUC 6836

View IAUC 6835 in .dvi or .ps format.
IAUC number 

                                                 Circular No. 6835
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/iau/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


SUPERNOVAE 1998S AND 1998T
     Y. L. Qiu, Beijing Astronomical Observatory, reports that the
discoveries of SN 1998S and SN 1998T were made from CCD frames
taken on Mar. 2.68 and Mar. 2.67 UT, respectively (not Mar. 3, as
reported on IAUC 6829 and 6830).  CCD images taken on Feb. 23.7
show no star at the position of SN 1998S; images taken on Feb. 7.8
show no star at the position of SN 1998T.  Magnitude estimates
(visual unless otherwise noted) for SN 1998S:  Mar. 7.69 UT, 12.6
(S. Yoshida, Waseda University, Japan); 9.91, 12.5 (J. C. Merlin,
Le Creusot, France; CCD, using GSC stars); 10.18, 12.8 (P. Schmeer,
Bischmisheim, Germany).  Corrigendum.  On IAUC 6832, line 10, for
A.J. 289, 52)  read  Ap.J. 289, 52)


AX J0049-729
     J. Yokogawa and K. Koyama, Kyoto University, report:  "An ASCA
observation made on 1997 Nov. 13 revealed a new x-ray pulsar at R.A.
= 0h49m01s, Decl. = -72o51'46'' (equinox 2000.0; +/- 2' at 90-
percent confidence) with a pulsation period of 74.675 +/- 0.006 s.
This would seem to be the same source having the pulsation period
of 74.8 +/- 0.4 s in the RXTE 2-deg field-of-view centered on SMC
X-3 (IAUC 6803).  The x-ray flux in the band 0.7-10 keV was 1.2 x
10E-11 erg sE-1 cmE-2, with sinusoidal pulse modulation.  The
spectrum was flat, with a power law having a photon index of 0.9
+/- 0.1."


IRAS 18325-5926
     A. C. Fabian, J. C. Lee, K. Iwasawa, Institute of Astronomy,
University of Cambridge; W. N. Brandt, Department of Astronomy and
Astrophysics, Pennsylvania State University; and C. S. Reynolds,
JILA, University of Colorado, report the presence of periodicities
of 11 and 7.8 hr in RXTE observations of the Seyfert galaxy IRAS
18325-5926 on 1997 Dec. 25-27 and 1998 Feb. 21-23, respectively:
"These are significantly shorter than the period found in ASCA data
from 1997 March of 16 hr (see
http://xxx.lanl.gov/abs/astro-ph/?9801226).  The power spectrum of
the February lightcurve also shows other strong peaks.  It is
likely that these are due to quasiperiodic oscillations in this
massive system, similar to those found in some Galactic blackhole
candidates.  The changing period is also consistent with the
hypothesis of a binary blackhole merger event, which would then
occur on or before 1998 Apr. 21.  Despite the low a priori
probability for such an event, we report it for its potential
importance.  We urge further observations at all wavelengths."

                      (C) Copyright 1998 CBAT
1998 March 10                  (6835)            Daniel W. E. Green

Read IAUC 6834 SEARCH Read IAUC 6836

View IAUC 6835 in .dvi or .ps format.

Our Web policy. Index to the CBAT/MPC/ICQ pages.

Valid HTML 4.01!