ATel #157; M. Chernyakova (ISDC, Geneva), A. Lutovinov (IKI, Moscow), F. Capitanio (CNR, Rome), N. Lund (DSRI, Copenhagen), N. Gehrels (GSFC/NASA)
on 2 May 2003; 16:41 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Masha Chernyakova (Masha.Chernyakova@obs.unige.ch)
Subjects: X-ray, Gamma Ray, Request for Observations, Transient
We report the discovery of a new transient source, IGR J18483-0311,
with the IBIS/ISGRI detector onboard the INTEGRAL observatory.
The source position is RA=18h48.3m and DEC=-03o11m (equinox 2000),
with uncertainty ~2' (including statistical and systematical errors).
This position is 0.7 arcminute from the position of the ROSAT source
1RXH J184817.3-031017 and more than 11 arc minutes from the known
X-ray sources EXO846-031, GRO J1849-03 and GS1845-03.
The source was detected during observations of the Galactic Centre
field performed between April 23.00 and April 28.65, with fluxes
~10 mCrab in the 15-40 keV band (signal to noise ratio S/N ~21)
and ~5 mCrab in the 40-100 keV band (S/N ~11).
A possible outburst was observed between UT 04:57 - 05:27 on April 26.
During this period the source flux increased up to ~40 mCrab in the
15-40 keV energy band (S/N ~7.3).
The X-ray monitor JEMX onboard the INTEGRAL gives for this source a
conservative upper limit of 20 mCrab in the 4-18 keV energy range.
We encourage follow up observations at various wavelengths.