TITLE: GCN CIRCULAR NUMBER: 30884 SUBJECT: GRB 210919A OSN 1.5m Source Confirmation DATE: 21/09/26 23:01:27 GMT FROM: Alexander Kann at IAA-CSIC <kann@iaa.es> D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), and F. Aceituno (IAA) report: We obtained observations of the enhance XRT position (Goad et al., GCN 30850) of the Swift short GRB 210919A (Tohuvavohu et al., GCN #30846) with the 1.5m telescope of OSN, Granada, Spain. We obtained 35 x 120 s images in the Rc band, starting at 03:28:22 UT on September 19, under good observing conditions. We obtained a second epoch, with 41 x 120 s images, the following night, starting at 2:59:51 UT on September 20. The source detected by Kann et al. (GCN #30883) is very faintly detected in the first epoch. Using the same comparison stars from the PanSTARRS catalog as used by Kann et al. (GCN #30883) (transformed to Rc via the Lupton equations, then transformed back to AB magnitudes), we measure: Rc = 24.47 +/- 0.53 mag @ 0.14944 d after trigger (AB mag). The source is undetected in the second epoch, but it is shallower, with Rc > 23.6 mag (AB) @ 1.13649 d after the GRB. We note this detection is also fainter than the upper limits listed in Kann et al. (GCN #30883).