TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4955 SUBJECT: GRB 060403 Optical observations DATE: 06/04/07 09:30:20 GMT FROM: Yuji Urata at RIKEN Y.Q. Lou, X.F. Wang (THCA), W.K. Zheng, Y.L. Qiu(NAOC), I.C. Yen (NTNU), C.S. Lin, H.C. Lin, K.Y. Huang (NCU), Y. Urata (Saitama U/RIKEN) on behalf of EAFON report "We have observed GRB 060403 X-ray afterglow position (Boyd et al. GCN 4945, Mangano et al. GCN 4947) using Xinglong (China) 0.8m and Lulin (Taiwan) 1.0m telescopes on April 3 and 5. In I-band images taken at Lulin, we found two sources at the X-ray error region which do not appear in DSSII images. Since our I-band images are deeper than DSSII, we have monitored the sources. These sources do not show any significant variabilities in our observational period. Thus we conclude that these two sources do not related with GRB afterglow. The limiting magnitude are summarize below. ------------------------------------------------------- Date Delay (h) Site Filter Exp.(s) Limit mag ------------------------------------------------------- Apr. 3 6.07 Xinglong R 600s x 12 20.4 Apr. 3 5.87 Lulin I 300s x 5 21.0 Apr. 5 55.63 Lulin I 300s x 2 19.6 ------------------------------------------------------- This message may be cited."