TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1419 SUBJECT: GRB 020418, optical/near-IR observations DATE: 02/06/08 04:49:45 GMT FROM: Javier Gorosabel at LAEFF-INTA, Madrid J. Gorosabel* (IAA-CSIC Granada), J. Hjorth, P. Jakobsson, J. Rasmussen, B. L. Jensen, H. Pedersen (Univ. of Copenhagen), J. M. Castro Ceron* (ROA San Fernando), A. Hornstrup (DSRI Copenhagen), A.O. Jaunsen (ESO Paranal), M. Weidinger, J. Fynbo* (IFA Aarhus), M. I. Andersen (Univ. of Oulu), P. Moller (ESO Garching), S. Holland (Univ. of Notre Dame), A. J. Castro-Tirado (IAA-CSIC Granada), E. Pian (INAF, OA Trieste), A. Fruchter (STScI, Baltimore), J. Greiner (MPE Garching and AI Potsdam), L. Kaper, E. van den Heuvel (Univ. of Amsterdam), on behalf of the GRACE collaboration, report: We summarise the results of an optical and near-infrared search for the afterglow of GRB 020418 carried out with the 1.54-m Danish Telescope and the 3.58-m New Technology Telescope, both at ESO's La Silla observatory. The log of the observations is displayed in the following table: ========================================================================= Date UT Filter ExpTime Telescope Seeing Time since Error box 2002 (s) (+Instrument) (") GRB (days) Coverage (%) -------------------------------------------------------------------------- April 19.9435--20.0066 Ks 45x60 3.58NTT(+SOFI) 0.65 1.6150 60** April 19.9445--19.9935 J 20x60 3.58NTT(+SOFI) 0.65 1.6089 60** April 19.9760--20.0507 R 10x420 1.54D(+DFOSC) 1.05 1.6532 100 April 20.9541--21.0177 Ks 45x60 3.58NTT(+SOFI) 0.70 2.6258 60** April 20.9551--21.0052 J 20x60 3.58NTT(+SOFI) 0.70 2.6200 60** April 20.9720--21.0340 R 6x500 1.54D(+DFOSC) 0.90 2.6429 100 June 01.9642--02.0267 R 9x500 1.54D(+DFOSC) 1.90 44.6353 100 June 02.9592--03.0155 R 8x500 1.54D(+DFOSC) 1.40 45.6273 100 -------------------------------------------------------------------------- ** Central part ========================================================================== Comparison of the images reveals no variable source contained in the error box brighter than R = 23.0. Correcting for the effect of the Galactic extinction, the R-band upper limit corresponds to R = 22.3. For the central part of the error box (the 60% of the error box covered for SOFI) we can set limits of Ks >= 21.0, J >= 22.6 and R >= 22.3 for any variable source (magnitudes corrected for Galactic reddening). We acknowledge the assistance of L. Vanzi at La Silla. --------------------------------------------------------------------------- * Visiting the Astronomical Observatory of the University of Copenhagen.