TITLE: GCN CIRCULAR NUMBER: 22214 SUBJECT: GRB 171209A: LCO 1-m telescope observations DATE: 17/12/09 18:11:27 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large collaboration report: We observed Swift GRB171209A (LaPorte et al. GCN 22213) on December 9, 16:25 UT (1.65 hours post burst) with one of the 1-m LCO telescopes in Siding Springs in the SDSS ri filters. We detect the UVOT candidate, which is not visible in archival Pan-STARRS images, with the following magnitudes: Mid Time     Exposure        Filter     Magnitude (AB) (hr)           (s) ------------------------------------------------------ 1.69          2x120          SDSS-R       18.2 +- 0.3 1.78          2x120          SDSS-I       17.8 +- 0.3 ------------------------------------------------------ as calibrated against nearby Pan-STARRS objects. Due to the vicinity of (~4") of a bright object, our estimated magnitudes are to be taken cautiously.