TITLE: GCN CIRCULAR NUMBER: 11996 SUBJECT: GRB 110503A - TLS Afterglow Observations DATE: 11/05/03 23:19:12 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, S. Schmidl, C. Hoegner, B. Stecklum, S. Schumann and M. Hartmann (TLS Tautenburg) report: We observed the afterglow of GRB 110503A (M. Stamatikos et al., GCN 11991, G. Leloudas et al., GCN 11994) at z=1.613 (A. de Ugarte Postigo et al., GCN 11993) with the 2m/1.34m Schmidt telescope of the Thueringer Landessternwarte Tautenburg under excellent observing conditions (low airmass, good transparency and seeing) starting during dawn at 0.098715 days after the GRB. Observations consisted of 3 x 180 s each in Z, Ic, Rc, V, B, followed by 3 x 300 s each in Z, Ic, Rc, V, B. The afterglow is detected on the single images. Assuming the USNO-B1.0 1421-0227752 star at RA = 08:51:10.01 (132.791692) Dec. = +52:11:04.75 (+52.184653) has R = 16.91 (mean of R1 and R2 mags, 0.06 mags difference), we find for two Rc band observations: t (days after trigger) = 0.1187616, Rc = 19.07 +/- 0.03 t (days after trigger) = 0.1750347, Rc = 19.51 +/- 0.04 Errors are statistical only. Observations are continuing as weather permits with 600 s exposures in all five colors. This message may be cited.