TITLE: GCN GRB OBSERVATION REPORT NUMBER: 396 SUBJECT: GRB 990806, optical observations DATE: 99/08/08 12:32:55 GMT FROM: Jochen Greiner at Astrophys.Inst. Potsdam,Germany J. Greiner (AI Potsdam, Germany), E. Pompei (ESO, Chile), S. Els (ESO, Chile), D. Pinfield (Queens Univ. Belfast, Ireland), S. Brillant (ESO, Chile), M. Sterzik (ESO, Chile), C. Wolf (MPIA Heidelberg), and A. Antonelli (Rome Obs., Italy) for the BeppoSAX team report: We have obtained BRI images of the GRB 990806 location (BeppoSAX mail n. 99/22 = GCN #392, BeppoSAX mail n. 99/23 = GCN #393) with EFOSC at the 3.6 m and the Wide-Field Imager at the 2.2 m telescopes at La Silla/ESO beginning at 14.5 hrs after the GRB event. The detailed observations were as follows: Telescope Start time (UT) Filter Expo.Time 2.2 m 07-08-1999 4:58 R 900 sec 2.2 m 07-08-1999 5:15 R 900 sec 3.6 m 07-08-1999 8:08 B 1500 sec 2.2 m 07-08-1999 9:52 I 1200 sec 2.2 m 07-08-1999 10:14 R 830 sec 3.6 m 08-08-1999 7:36 B 1800 sec 2.2 m 08-08-1999 8:45 R 900 sec 2.2 m 08-08-1999 9:02 R 900 sec 2.2 m 08-08-1999 9:18 R 900 sec 2.2 m 08-08-1999 9:37 I 900 sec 2.2 m 08-08-1999 9:53 I 900 sec Comparison of the (summed R) images of the two nights do not show any object with brightness variation more than 0.3 mag down to B = 25.2 mag, R = 23.5 mag and I = 18.0 mag. Photometric calibration was done against standard stars in the field SA 113, and the R band calibration is basically identical to that given in GCN #395.