TITLE: GCN CIRCULAR NUMBER: 30983 SUBJECT: GRB 210919A: FORS2/VLT observations DATE: 21/10/25 00:51:58 GMT FROM: Alexander Kann at IAA-CSIC <kann@iaa.es> D. A. Kann (HETH/IAA-CSIC), D. B. Malesani (Radboud U. Nijmegen), V. D'Elia (ASI/SSDC, INAF/OAR), A. de Ugarte Postigo (HETH,DARK/NBI), A. Rossi (INAF-OAS) and C. C. Thoene (HETH/IAA-CSIC) report on behalf of the Stargate consortium: We observed the field of the short GRB 210919A (Tohuvavohu et al., GCN #30846) at late times with FORS2 mounted on the ESO VLT at Cerro Paranal Observatory, Chile. We obtained 6 x 90 s exposure each in V, Rc, and Ic, and 12 x 68 s in z_special, under excellent conditions (seeing 0".9 to 0".65 from V to z), on October 2.28 UT, 2021, at a midtime of 13.26 days after the GRB. Our results are in agreement with the LDT/LMI observations obtained by O'Connor et al. (GCN #30934). At the position of the potential afterglow (Kann et al., GCN #30883, #30884), we do not detect any source. Calibrating against three nearby stars from the Pan-STARRS catalog (converted to Johnson-Cousins filters for V, Rc, Ic, following the Lupton transformations, then converted back to AB magnitudes), we derive an upper limit of Ic > 25.8 mag, with the V, Rc observations reaching a comparable depth and the z observation being shallower. The nearby source reported by O'Connor et al. (GCN #30934) is detected in all filters, and we find that it is marginally extended. We measure, again in AB magnitudes, Ic = 23.83 +/- 0.06 mag in an aperture corresponding to the stellar PSF, it being somewhat brighter using a larger aperture. Therefore, this object is a host galaxy candidate for GRB 210919A, in agreement with O'Connor et al. (GCN #30934). At the eastern edge of the XRT error circle (Goad et al., GCN #30850), we find a further, fainter source at RA = 5:21:01.35, Dec. = +1:18:41.9 (J2000) with an error of 0".5. For this source, we measure Ic = 25.01 +/- 0.19 mag. As the source is faint, we can't make any definite statements about its extension. It is also a host galaxy candidate, although its chance association probability is quite large.