TITLE: GCN CIRCULAR NUMBER: 6972 SUBJECT: GRB 071021: Z-band detection DATE: 07/10/22 02:18:51 GMT FROM: Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center D. Malesani (DARK), S. Piranomonte (INAF/OARm), G. Tagliaferri, G. Chincarini, S. Covino (INAF/OABr), F. Fiore, L. Stella (INAF/OAR), report on behalf of the MISTICI collaboration: We observed the field of GRB 071021 (Sakamoto et al., GCN 6958) with the 8.2m VLT+FORS2 equipped with the z_Gunn filter (effective wavelength: 9100 A; FWHM: 1300 A). In a coadded image totalling 15 min exposure, we see a weak source at the coordinates provided by Castro-Tirado et al. (GCNs 6968, 6971). Our detection would suggest a redshift less than roughly 6.5. A finding chart is poste at: http://www.astro.ku.dk/~malesani/GRB/071021/071021_finder.jpg We acknowledge excellent support from the ESO staff, particularly Hugues Sana.