TITLE: GCN CIRCULAR NUMBER: 33549 SUBJECT: GRB 23038B: CAHA 2.2m/CAFOS detection DATE: 23/03/31 19:29:32 GMT FROM: J. F. Agui Fernandez at IAA-CSIC feli@iaa.es

J. F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA/CNRS), C. C. Thoene (ASU-CAS), M. Blazek (CAHA) , Ana Guijarro (CAHA) and S. Cikota (CAHA) report:

We observed the afterglow of GR230328B (Fermi/GBM Detection: Fermi GBM Team GCN 33526, Swift detection: Gropp et al. GCN 33527) with CAFOS mounted on the 2.2 m telescope at the Calar Alto Observatory (Almeria, Spain). The observations consisted of 5 x 360 s in Rc-band and were obtained at mean epoch of 0.4717 days after the GRB. The afterglow is clearly detected with Rc = 21.00 ± 0.06 (AB) mag measured against comparison stars from the PanSTARRS catalogue.