TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1329 SUBJECT: Fading Optical Afterglow and Possible Host Galaxy of GRB 020405 DATE: 02/04/06 11:50:11 GMT FROM: Jens Hjorth at U.Copenhagen Fading Optical Afterglow and Possible Host Galaxy of GRB 020405 J. Hjorth (U. Copenhagen), J. Fynbo (ESO), E. Pian (INAF, OA Trieste), A. Delsanti (ESO), B. L. Jensen (U. Copenhagen), J. Gorosabel (IAA, Granada), H. Pedersen (U. Copenhagen), and M. I. Andersen (U. Oulu) report: Optical images of the candidate afterglow (Price et al., GCN #1326) of GRB 020405 (Hurley et al., GCN #1325) were obtained at the Danish 1.5-m telescope on La Silla as follows: Date Filter Exp. time 6 April 2002 UT (sec) 03:16 R 600 05:04 R 600 05:16 V 600 05:37 B 1200 05:56 Gunn i 900 Calibrating our photometry to the reference star USNO525_16813005 (for which we assume B = 19.3 and R = 17.8) we find R = 20.9 and B - R = 0.0. In addition, comparison between the two R-band images indicates that the afterglow faded with 0.099 +- 0.040 mag between the two epochs, thus supporting the interpretation that the source is indeed the afterglow of GRB 020405. A color image (based on the BVi images) posted at http://www.astro.ku.dk/~jens/grb020405_color.gif shows the very blue color of the afterglow (see also Castro-Tirado et al., GCN #1327). In addition, the R-band images posted at http://www.astro.ku.dk/~jens/grb020405_host1.gif http://www.astro.ku.dk/~jens/grb020405_host2.gif reveal a bright galaxy located ~ 2" to the south-west of the afterglow. If this is the host galaxy, then the redshift of GRB 020405 may be fairly low, making it a good candidate for a search of an underlying supernova.