TITLE: GCN CIRCULAR NUMBER: 10413 SUBJECT: GRB 100213B: NOT optical observations DATE: 10/02/14 00:44:21 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), N.R. Tanvir (Univ. Leicester), D. Xu (WIS, DARK/NBI), G. Leloudas (DARK/NBI), P. Jakobsson (Univ. Iceland), A. Somero, and S. Katajainen (Tuorla Obs.), report on behalf of a larger collaboration: We observed the field of GRB 100213B (Vetere et al., GCN 10412) with the NOT equipped with ALFOSC. Due to adverse weather, we could only obtain one 5-min R-band exposure, starting on Feb 13.970 UT (19 min after the GRB). We find an object with R ~ 21.5 located just outside the edge of the XRT error circle, at coordinates RA = 08:17:07.97, Dec = +43:26:54.6. This location is 8 arcsec away of the X-ray position, which has a reported error radius of 5.2" (Vetere et al., GCN 10412). The object seems elongated in our image. However, it is not visible in the SDSS data of this field, and may therefore be the afterglow of GRB 100213B. Inside the XRT error circle, there is also a possible source close to our image detection limit (R ~ 22.2), at coordinates RA = 08:17:08.48, Dec = +43:26:50.3 (0.8" uncertainty). Given the low S/N, the reality of this source cannot be confirmed. Further observations are encouraged. The NOT may attempt again later tonight depending on the weather conditions.