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GCN Circular 33381

GRB 230228A: Nanshan/NEXT optical upper limit
2023-02-28T16:50:31Z (a year ago)
Dong Xu at NAOC/CAS <>
T.H. Lu, S.Q. Jiang, S.Y. Fu, X. Liu (NAOC), Z.P. Zhu (NAOC, HUST), D. 
Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 230228A detected by Swift (Dichiara et al., 
GCN 33378) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, 
China. We obtained 12x200 s frames in the Sloan r-band and 12x200 s 
frames in the Sloan z-band, starting at 14:37:32 UT on 2023-02-28 (i.e., 
8.77 hr after the BAT trigger).

No optical source is detected in our stacked images at the enhanced XRT 
position (Evans, GCN 33379), and preliminary photometric results are as 

T_mid-T0 (hr)    Filter   Upper limit(3-sigma)
    9.86                r          >20.6
    9.14                z          >19.5

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