TITLE: GCN CIRCULAR NUMBER: 10677 SUBJECT: GRB 100424A : Lulin early z'-band upper limit DATE: 10/04/25 07:46:11 GMT FROM: Yuji Urata at Nat. Central U. K.Y. Huang (ASIAA), Y. Urata, P. Tsai (NCU) on behalf of EAFON report; We observed the field of GRB 100424A (Hoversten et al., GCN 10667) in r' and z'-band with the LOT. Observations started at 17:52 UT on April 24, ~80 min after the Swift Trigger. In our z'-band stacked image shows no new object within the enhanced Swift/XRT position (Evans et al., GCN 10669) down to the following preliminary limiting magnitudes, ---------------------------- Time(hr) Filter Limit(AB) ---------------------------- 2.16 z' 20.6 ----------------------------