GCN Circular 30385
P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), A. Fiorenzano, C. Padilla (INAF-TNG) on behalf of the CIBO collaboration report: We observed the field of GRB 210704A (Kunzweiler et al., GCN Circ. 30369; Ursi et al., GCN Circ. 30372; Berretta et al., GCN Circ. 30375; Prasad et al., GCN 30378; Malacaria et al. GCN 30380), covering the position of the X-ray afterglow reported by D'Ai et al. (GCN Circ. 30379) with the Italian 3.6m TNG telescope equipped with the optical camera DOLORES. A series of images were obtained with the r-sdss filter on 2021-07-05 from 21:13:11 UT to 21:39:50 UT (i.e. about 1.08 days after the burst). The optical afterglow candidate reported by Kim et al. (GCN Circ. 30384) is clearly detected at the following position (J2000): RA: 10:36:04.92 Dec: +57:12:59.3 (+/- 0.5"). With preliminary photometry we derive the following magnitude: r = 22.13 +/- 0.13 (AB; calibrated against the SDSS catalogue). As noted by Kim et al. (GCN Circ. 30384), this source is not visible in archival SDSS and Pan-STARRS images.