TITLE:   GCN CIRCULAR
NUMBER:  39624
SUBJECT: EP250308a: NOT optical upper limit
DATE:    25/03/09 05:18:36 GMT
FROM:    Zipei Zhu at NAOC <zpzhu@nao.cas.cn>

Z.P. Zhu, X. Liu, Jie An, S.Q. Jiang, D. Xu (NAOC), S.Y. Fu (HUST, NAOC), D. B. Malesani (DAWN/NBI and Radboud U.), P. Jonker (Radboud U.), A. H. Fuente (NOT) report on behalf of a large collaboration:

We observed the field of EP250308a detected by EP/WXT (Trigger ID: 01709132392), using the ALFOSC instruments mounted on the Nordic Optical Telescope (NOT), with 3 x 300 s in the SDSS-r band. 

Preliminary analysis shows that no new source is detected within the EP/WXT error circle, down to the 5-sigma upper limits of r > ~ 22.7 (AB) at ~ 0.41 day after the EP trigger, calibrated with nearby Pan-STARRS stars and without Galactic extinction correction.