TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5509 SUBJECT: GRB 060904B BOOTES-IR and 1.5m OSN observations DATE: 06/09/04 04:28:18 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo, F. Aceituno, A.J. Castro-Tirado (IAA-CSIC Granada), P. Kubanek (ASU AV CR ndrejov & ISDC Versoix) on behalf of a larger collaboration report: "The 0.6m BOOTES-IR and 1.5m telescope, located at IAA-CSIC Observatorio de Sierra Nevada in Granada (Spain), observed the SWIFT error box for GRB 060904B (Grupe et al. GCN 5505) starting at 02:38:30 UT observing in I & R-bands. We clearly detect the optical counterpart reported by Rykoff et al. (GCN 5504), at coordinates J2000 (+/-0.5"): 03:52:50.54 -00:43:30.5 >From 02:38:30 to 02:48:35 UT the object has declined in 0.66 +/- 0.17 magnitudes. This message is quotable." [GCN OPS NOTE(04sep06): Per author's request, the 'B' was added.]