TITLE:   GCN CIRCULAR
NUMBER:  36962
SUBJECT: GRB 240727A: NOT optical observation
DATE:    24/07/28 09:40:19 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

J. An, S.Y. Fu, S.Q. Jiang, X. Liu, Z.P. Zhu, D. Xu (NAOC), S.G. Sorensen (NOT) report on behalf of a large collaboration:

We observed the field of GRB 240727A detected by Swift (Parsotan et al., GCN 36938) using the the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We obtained 6x300 s Sloan r-band images at a median time of 21:45:11.8 UT on 2024-07-27.

The optical afterglow (Zheng & Filippenko, GCN 36939; Liu et al., GCN 36940; Dubay et al., GCN 36941) is clearly detected in our stacked r-band image with r = 23.4 +/- 0.1 mag, calibrated with nearby Pan-STARRS stars and not corrected for Galactic extinction.