ISO observations of the GRB 970402 error box
Altieri, B.; Palazzi, E.; Frontera, F.; Costa, E.; Hanlon, L.; McBreen, B.; Smith, N.; Metcalfe, L.; Nicastro, L.; Gorosabel, J.; Feroci, M.; Castro-Tirado, A. J.; Claret, A.; Laureijs, R.; Kessler, M.
Spain, Ireland, Italy, France
Abstract
Following the detection by BeppoSAX of GRB 970402, a Target-of-Opportunity Observation by ISO was scheduled for 5 April, about 55-hours after the event, i.e. simultaneous with a second BeppoSAX pointing. The CAM instrument was used in the 6('') /pixel mode, in the 8-15 mu m band (IRAS) for covering the entire BeppoSAX GRB error box. A further observation was carried out on 13 April, with a similar set-up. Imaging was performed with the 6('') /pixel mode in the GRB error box, and with the 1.5('') /pixel field of view, in the smaller X-ray source error box. A PHT observation was also performed on 5 April. About 50 sources were detected with ISOCAM in a field centred in the GRB error box. 7 of them lie within the smaller X-ray error circle. With the exception of the variable star BL Cir, no other variable object was found in the entire GRB error box. 5-sigma upper limits for any new object are F_{(12microns )} <= 0.14 mJy and F_{(174microns )} <= 350 mJy. Based on observations obtained with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) with the participation of ISAS and NASA.