TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5549 SUBJECT: GRB 060904B : CFHT/WIRCam NIR afterglow observations DATE: 06/09/08 11:56:31 GMT FROM: Yuji Urata at Saitama U K.Y. Huang, W.H. Ip, Y.S. Lee (NCU) and Y. Urata (Saitama Univ.) on behalf of EAFON report: "The NIR afterglow observations of GRB 060904B (Grup et al.; Rykoff et al; Fugazza et al.) with CFHT/WICam started from 9.40 hours after the GRB occurred. Our J and Ks images show the magnitude of the afterglow are J~ 19 at 10.8 hours and Ks~ 17 at 9.4 hours (compare with 2MASS stars). Refer to the SMART observations (Cobb et al., GCN 5515), our J band result indicates the decay rate (Flux ~ t^alpha) may change form ~- 0.65 to ~ -1.37. However, we do not find the decay rate change from our Ks band results. We would like to thank CFHT/WIRCam staff, especially A. Loic and P. Martin for their assistance. This message may be cited."