TITLE: GCN CIRCULAR NUMBER: 19491 SUBJECT: GRB 160601A: GTC observations confirming transient source decay DATE: 16/06/02 15:00:10 GMT FROM: Juan Carlos Tello at IAA-CSIC J. C. Tello, Y. Hu (IAA-CSIC), A.J. Castro-Tirado (IAA-CSIC, ISA-UMA), S. Oates (Warwick U.), A. Perez-Romero and D. Garcia-Alvarez (GTC-IAC) on behalf of a larger collaboration, report: We observed the field of GRB 160601A (Kocevski et al., GCN 19478) with the Gran Telescopio Canarias (GTC) with the OSIRIS instrument and acquired 6x100s images starting 01:37:31 UT and ending 01:49:29 UT on July 2nd (10h54m-11h06m after the Swift trigger) and we detect the afterglow candidates reported by Malesani et al. (GCN 19485). We also find like Schulze (GCN 19488) that Object 1 is fading and at the time of our observations was at a magntude of ~ 23.5 in the Sloan_r filter and calibrated to SDSS Release 6. We note that our observations precede Schulze's by 2.5 hours and are slightly fainter but not much more than the uncertainty of these preliminary results, implying either a rebrightening event or a plateau due to either afterglow behaviour or host galaxy. [GCN OPS NOTE903jun16): Per author's request, AP-R and DG-A were added to the author list.]