GCN Circular 445
Subject
BeppoSAX NFI Observation of GRB991106
Event
Date
1999-11-11T17:44:27Z (27 years ago)
From
Angelo Antonelli at Obs. Astro. di Roma <angelo@quasar.mporzio.astro.it>
L.A. Antonelli, Osservatorio Astronomico di Roma;
G. Gandolfi, M. Feroci, Istituto di Astrofisica Spaziale, CNR, Rome,
D. Ricci, C. De Libero, M. Capalbi, BeppoSAX Science Operations Center,
Telespazio, Rome; F. Frontera, Istituto Tecnologie e Studio Radiazioni
Extraterrestri, CNR, Bologna, J. in 't Zand and J. Heise, Space Research
Organization Netherlands, Utrecht, on behalf of the BeppoSAX Team report:
"The region of GRB 991106 (GCN #434) was observed with the Narrow
Field Instruments (NFI) on board BeppoSAX from Nov. 6.781 to 7.565 U.T.
(starting about 8 hrs after the burst trigger time) for a total net
exposure time of 32 ks. In the 2-10 keV image of all data from both
Medium-Energy Concentrator Spectrometer units 2 and 3, a faint point
source (1 SAX J222441+5422.7) is detected, with a chance probability
for the source being a background fluctuation of 5E-4, within the WFC
error box (Gandolfi et al, GCN #435). The average source flux in
2-10 keV band was (1.7+-0.4)x10E-3 counts/s corresponding to
1.25x10E-13 erg cmE-2 sE-1, assuming a crab-like spectrum.
The source position is R.A. = 22h24m40.8s, Dec.= +54d22'45" (Eq. 2000.0)
and the error radius is 1'.5.
The radio source reported by Frail (GCN #444) is 2'.1 from this X-ray
source position and it lies outside the NFI error circle. The data do
not allow to draw a useful constraint about the variability of this source.
The probability of detecting a foreground source at this flux level or
brighter in the WFC error circle is expected to be ~10% as suggested by the
BeppoSAX LogN-LogS (Fiore et al., 1999).
This message is citable."