TITLE:   GCN CIRCULAR
NUMBER:  32532
SUBJECT: GRB 220907A: Nanshan/NEXT optical upper limits
DATE:    22/09/08 13:04:59 GMT
FROM:    Zipei Zhu at NAOC  <zpzhu@nao.cas.cn>

Z.P. Zhu (NAOC,HUST), S.Y. Fu(NAOC), S.Q. Jiang, X. Liu, T.H. Lu, D. Xu, X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 220907A detected by Swift (Page et al., GCN 32526) and Fermi/GBM (GCN 32525) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained a series of frames in the Sloan r-band and Sloan z-band, starting at 14:07:13 UT on 2022-09-07, i.e., 108s after the BAT trigger.

No uncatalogued optical source is detected in our stacked images at the XRT position (Page eta al., GCN32527), with upper limits as follows:

T_mid-T0 (min)    Filter   Upper limit(3-sigma)
    15.5                 r          >19.5
    34.5                 z          >18.1

calibrated with the nearby PanSTARRS field and not corrected for Galactic extinction.