TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2471 SUBJECT: GRB 031203: IR NTTobservations do not confirm REM detection DATE: 03/12/05 12:39:50 GMT FROM: Gianpiero Tagliaferri at OAB-INAF GRB 031203: IR NTT observations do not confirm REM detection F.M. Zerbi, G. Chincarini, S. Covino, E. Molinari, A. Di Paola, D. Fugazza, V. Testa, M. Rodono', L.A. Antonelli, P. Conconi, G. Cutispoto, L. Nicastro, G. Tosti, L. Burderi, S. Campana, C. Campeggi, G. Crimi, R. Cunniffe, J. Danzinger, A. Fernandez-Soto, F. Fiore, F. Frontera, G. Gentile, G. Ghisellini, P. Goldoni, G. Israel, B. Jordan, D. Lazzati, D. Lorenzetti, D. Malesani, E. Martinetti, N. Masetti, R. Mazzoleni, B. Mc Breen, A. Melandri, S. Messina, E. Meurs, A. Monfardini, G. Nucciarelli, M. Orlandini, J. Paul, E. Palazzi, E. Pian, P. Saracco, S. Sardone, A. Simoncelli, M. Stefanon, L. Stella, L. Tagliaferri, M. Tavani, G. Tosti, S. Vergani, F. Vitali. We observed in JHKs filters with SofI at the NTT telescope the field of the INTEGRAL GRB 031203 (Gotz et al. GCN 2459) starting at 4 December 04h54m UT. The object detected by the REM telescope in the H and Ks filters (see Zerbi et al. GCN 2466) was not detected in these images, with upper limits of J=22.2, H=21.1, Ks_1=20.9 and Ks_2=20.2 (we have two exposures in the Ks filter separated by about 2.5 hours). A reanalysis of the REM data confirmed the presence of the object reported in GCN 2466. We are still investigating the possible cause of it. The object reported by Hsia et al. (GCN2470), associated with the XMM source S1 (Santos-Lleo & Calderon GCN2464), is present in all SofI images, with magnitudes J=18.2+/-0.08, H=17.35+/-0.04 and Ks_1=16.45+/-0.03 (exposure of 45 min starting at UT 04:54 and ending at UT 05:47) and Ks_2=16.43+/-0.04 (exposure of 15 minutes starting at UT 07:30 and ending at 07:46). Therefore, this object remained constant in the two Ks images. Last night we observed the field also with the VLT telescope and the ISAAC camera. A report on the quick analysis of these data will be given later today.