Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits


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 6545  SEARCH Read IAUC 6547

View IAUC 6546 in .dvi or .ps format.
IAUC number

                                                 Circular No. 6546
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)

     T. Boller, F. Haberl, and W. Voges, Max-Planck-Institut fur
Extraterrestrische Physik, Garching; L. Piro, Istituto Astrofisica
Spaziale, CNR, Frascati; and J. Heise, Space Research Organization
of the Netherlands, report:  "Within the 10' error box centered on
the BeppoSAX position of the x-ray burst from Jan. 13.295011 UT
(IAUC 6538), we have found the single x-ray source 1RXS
J124938.0-590525, contained in the ROSAT All-Sky Survey Bright
Source Catalogue (IAUC 6420) at the position R.A. = 12h49m38s,
Decl. = -59o05'.4 (equinox 2000.0; estimated 1-sigma error 9"),
which is 5'.6 north of the BeppoSAX position, with a countrate of
4.09 +/- 0.27 counts/s (0.1-2.4 keV) observed during 1991 Aug. 4-5.
During four ROSAT PSPC observations centered on R.A. = 12h47m43s,
Decl. = -59o41'.4, and totalling 12 400 s between 1993 July 11 and
Aug. 27, two sources were detected within the BeppoSax error circle
with the following positions, mean countrates and fluxes (assuming
a power-law model):  source 1, R.A. = 12h49m39s, Decl. = -59o05'.2,
2.78 +/- 0.02 counts/s (0.1-2.4 keV), or 1.7 x 10E-10 erg cmE-2
sE-1 [for a power-law-fit value of the hydrogen column density NH =
(2.9 +/- 0.9) x 10E21 cmE-2 and photon index 2.1 +/- 0.2]; source 2,
R.A. = 12h49m27s, Decl. = -59o13'.3 (3'.9 south of the BeppoSAX
position), 0.08 +/- 0.002 counts/s (0.1-2.4 keV) or 2.2 x 10E-12
erg cmE-2 sE-1 [for power-law-fit NH = (0.4 +/- 0.1) x 10E21 cmE-2
and photon index 2.4 +/- 0.3].  Source 2 is probably a foreground
object because of the relatively-low-power-law-fit NH value.
Source 1 shows variability by +/- 20 percent during the pointing.
Source 2 is not detected in the ROSAT all-sky survey.  The upper
limit value of 0.03 counts/s implies a change by more than a factor
of 2 between the survey and pointing observations.  The ROSAT
source 1 (1RXS J124938.0-590525), as well as the BeppoSAX burster,
are very likely associated with 4U1246-58.  Flaring activity from
this source was seen in the past -- but, to our knowledge, a strong
and short burst such as that observed by BeppoSAX (IAUC 6538) was
never reported.  The flat-top light curve observed in this event
suggests a type-1 Eddington-limited burst."

     Corrigendum.  M. Cavagna and P. Sicoli report that their
measurement on IAUC 6537 was incorrect.  The proper position is
refined to read R.A. = 5h53m02s.97, Decl. = -17o52'23".5.

                      (C) Copyright 1997 CBAT
1997 January 27                (6546)            Daniel W. E. Green

Read IAUC 6545  SEARCH Read IAUC 6547

View IAUC 6546 in .dvi or .ps format.

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

Valid HTML 4.01!