TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1348 SUBJECT: X-ray afterglow of GRB020321 DATE: 02/04/10 12:09:39 GMT FROM: Jean int Zand at SRON J.J.M. in 't Zand, University of Utrecht and Space Research Organization Netherlands (SRON); L. Kuiper and J. Heise, SRON; L. Piro and G. Gandolfi, Istituto di Astrofisica Spaziale e Fisica Cosmica, Rome, report: "A refined analysis of the BeppoSAX Narrow Field Instruments data on GRB 020321, collected between 8.1 and 10.6 hrs after the burst, has resulted in a significance of only 3.0 for the tentative X-ray afterglow detection reported in GCN 1285. The source is also not confirmed by the XMM-Newton observation that took place between 10.3 and 24.2 hrs after the burst (see http://xmm.vilspa.esa.es/external/xmm_news/items/grb020321). Therefore, we regard this detection as marginal. We would like to point out another source which is outside the error circle of the marginal NFI source but inside the WFC error circle of the burst (GCN 1281) and which draws the attention through a comparison between the XMM-Newton EPIC-pn image and the Chandra ACIS-S3 observation (a 5.5 hr exposure starting 9.9 days after the burst; see Fox et al., GCN Circ. 1342). It concerns source No. 2 in the EPIC-pn image which is located at R.A. = 16h 12m 43.7s, Decl. = -83d 43' 13.9" (equinox 2000.0; error 4"). This source 1) is 0.9' from the WFC centroid; 2) shows a declining, though not smoothly, trend in the EPIC-pn photon count rate (see aforementioned Vilspa web page); 3) is the only EPIC-pn source covered but not detected in the ACIS-S3 image. Therefore, we propose that this is likely the X-ray afterglow and urge optical and radio observers to concentrate on this position for this 'dark' GRB. We thank P. Rodrigues, N. Schartel and M. Santos at the XMM-Newton Science Operations Centre (ESA) in Vilspa for advice on the XMM-Newton data." This message may be cited.