GCN Circular 31353
Subject
GRB 220101A: Xinglong-2.16m photometry and spectroscopy
Date
2022-01-01T15:51:07Z (2 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu (NAOC), Z.P. Zhu (NAOC, HUST), D. Xu, X. Liu, S.Q. Jiang (NAOC)
report on behalf of a larger collaboration:
We observed the field of GRB 220101A detected by Swift (Tohuvavohu et
al., GCN 31347) and Fermi (Arimoto et al., GCN 31350) using the
Xinglong-2.16m telescope equipped with the BFOSC camera. Observations
were carried out starting at 09:50:07 UT on 2022-01-01. We firstly
obtained 4x300 s frames in each of the B, V, R and I bands, and then
2x1800 s spectroscopy covering ~3800 - 8800 AA.
The optical afterglow of the burst (Tohuvavohu et al., GCN 31347) is
clearly detected in each of our stacked images in the V, R and I bands,
but no in the B band. Preliminary photometry is as follows:
Tmid-T0 (hr) Mag MagErr Filter
5.55 >21.43 N/A B
5.45 19.86 0.06 V
5.36 18.65 0.02 R
5.27 17.34 0.01 I
The spectrum is in low resolution and rather low S/N. However, a broad
absorption feature is evident centering at ~ 6820 AA, which can
interpreted as Ly_alpha absorption. Besides Ly_alpha, other weak lines
such as Si II, C II, Si IV are also detected at the common redshift of z
= 4.61. We thus conclude that z = 4.61 is likely the redshift of the GRB.
We thank the great support of the Xinglong-2.16m staff, in particular
Junjun Jia, Yinan Zhu, Aiying Zhou, and Jie Zheng.