1998A&A...330...14C

Following the detection by BeppoSAX of GRB 970402, a Target-of-Opportunity Observation by ISO was sheduled 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 µm 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-σ upper limits for any new object are F_(12µm)≤0.14mJy and F_(174µm)≤350mJy.