TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1433 SUBJECT: GRB 020531, INT+WFC deep optical upper limits DATE: 02/06/19 21:08:00 GMT FROM: Evert Rol at U.Amsterdam Isabel Salamanca, Evert Rol (University of Amsterdam), Nial Tanvir (University of Hertfordshire), Lex Kaper (UoA), on behalf of a larger collaboration, report: "We have observed the error box of GRB 020531 (GCN #1399, #1402) with the Wide Field Camera on the 2.5m Isaac Newton Telescope, La Palma. The observations were performed in Harris V filter*, under non-photometric conditions. The field was calibrated with the calibration provided by Henden (GCN #1422). The results are summarized below: mid-exposure exposure time lim. magn. seeing (UT days) (min) (3 sigma) (arcsec) May 31.92 30 24.7 1.4 June 2.99 40 25.2 1.2 We do not measure any source fading by more than 0.3 magnitude between the two epochs. A refined analysis of the Chandra sources (GCN #1415, #1426) visible in our images is being carried out and will be published in a following GCN Circular. An image including the IPN errorbox can be found at http://www.astro.uva.nl/~evert/grb020531/. We acknowledge the assistance of the ING staff." This message can be cited. *) The Harris V filter is close to the standard Landolt V filter. For the calibration, color correction terms have been used and can be found at http://www.ast.cam.ac.uk/~wfcsur/photom.html. [GCN OPS NOTE (19Jun02): This Circular was delayed 1.5 hours because of an obselete address in the vetted list.]