TITLE: GCN CIRCULAR NUMBER: 5979 SUBJECT: GRB 061222A: MITSuME Akeno optical upper limits DATE: 06/12/24 23:19:43 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Ishimura, Y. Yatsu, T. Shimokawabe, N. Vasquez, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the error box of GRB061222A (Grupe et al., GCN 5954) with the 3-color 50cm MITSuME Telescope at Akeno, Japan starting at 8:48:53 UT, 5.3 hours after the trigger. In the co-added images of Ic, Rc, and g' bands, we did not detect any new source in the XRT error circle. The 3-sigma limiting magnitudes based on USNO-B1.0 (I-band) and NOMAD (R-band,g'-band) stars are following. Filter start time end time Exp(s) Mag (3-sigma upper limit) ----------------------------------------------------------------- Ic 8:48:53 09:32:23 60s * 36 19.6 Rc 8:48:53 09:32:23 60s * 36 20.4 g' 8:48:53 09:32:23 60s * 36 20.6 -----------------------------------------------------------------