TITLE: GCN CIRCULAR NUMBER: 27348 SUBJECT: GRB 200306C: Calar Alto 2.2m upper limit DATE: 20/03/08 07:43:45 GMT FROM: Alexander Kann at IAA-CSIC D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Blazek, C. C. Thoene, J. F. Agui Fernandez (all HETH/IAA-CSIC), R. Pedro Hedrosa, and E. Gallego (both CAHA) report: We observed the field of the afterglow of GRB 200306C (Lipunov et al., GCNs #27324, #27325; Gropp et al., GCN #27326; Jelinek et al., GCN #27328; Hu et al., GCN #27329; Moskvitin, GCN #27333; Izzo & Perley, GCN #27334; Kann et al., GCN #27335; Steele et al., GCN #27338) with the 2.2m telescope of Calar Alto equipped with CAFOS. We obtained 4 x 720 s images in the Rc band under adverse conditions (moonlight, passing clouds, bright star still there). Our stacked image centred at mean epoch 1.25519 d after the GRB shows no detection to a 3-sigma upper limit of Rc > 23.0 mag (AB). The magnitude limit was obtained versus SDSS stars in the field.