TITLE: GCN CIRCULAR NUMBER: 6221 SUBJECT: GRB070223: confirmation of nIR and optical afterglow DATE: 07/03/23 17:18:46 GMT FROM: Evert Rol at U.Leicester E. Rol, N. Tanvir (Leicester), N. Mirabal (Columbia), K. Wiersema (Amsterdam), J.P. Halpern (Columbia), A. Levan (Warwick), R. Chapman (Hertfordshire), A. Melandri (Liverpool JMU) and D. Pinfield (Hertfordshire), report on behalf of a larger collaboration: We re-observed the position of the X-ray afterglow of GRB070223 (Vetere et al, GCN report 35.1) with the LIRIS instrument on the William Herschel Telescope, between 7.99 and 8.08 days after the burst. Our J and K images do not show any source inside the XRT 90% error circle. As our observations are considerably deeper than the first epoch LIRIS observations reported by Castro-Tirado et al (GCNC 6168; private communication), we conclude the source reported is the nIR afterglow of GRB070223. We also re-examined the optical images taken with the MDM telescope (Mirabal et al., GCNC 6162), and find a faint optical source at the position of the nIR afterglow. We point out that this is a different source than the one located at RA (J2000) = 10 13 48.19, Dec (J2000) = 43 07 54.7 (S1, GCNC 6162), which now also falls outside the revised XRT position (Vetere et al.). We derive a position for the optical afterglow of (J2000): RA = 10 13 48.39 Dec = +43 08 00.7 which fully agrees with the X-ray position (GCN report 35.1). Astrometry was done relative to the SDSS (Cool et al, GCNC 6128), and errors are about 0.3 arcsecond in each coordinate. The latest MDM image is posted at http://www.astro.columbia.edu/~mirabal/grb070223mdm.jpg