TITLE:   GCN CIRCULAR
NUMBER:  31320
SUBJECT: GRB 211227A: Nanshan/NEXT optical observations and host galaxy candidate
DATE:    21/12/28 02:22:53 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

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

We observed the field of GRB 211227A (Beardmore et al. GCN Circ. 31316) 
using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. 
Observations automatically started at 23:33:37 UT on 2021-12-27 (i.e., 
90.14 s after the BAT trigger), and a series of 40 s, 60 s, 90 s frames 
were obtained in the Sloan r-filter.

Within the Swift/XRT error circle (Beardmore et al. GCN Circ. 31316), no 
uncatalogued optical transient is detected in our stacked image down to 
a limiting magnitude of r ~ 20.0 mag, calibrated with the nearby 
PanSTARRS field.

However, there exists a known source at the border of the Swift/XRT 
error circle at coordinates: R.A. (J2000)=08:48:35.975 and Dec (J2000)= 
-02:44:06.93, which has r ~ 19.6 mag from Nanshan/NEXT, r ~ 19.40 mag 
and classified as galaxy with a photo-redshift of 0.244 +/- 0.0888 from 
SDSS, r ~ 19.47 mag from PanSTARRS, as well as r ~ 19.25 from Legacy 
Survey. No apparent brightening of the galaxy is seen in comparison of 
Nanshan/NEXT and different surveys, indicating that the contribution of 
the optical counterpart of the burst is negligible if the galaxy is the 
host of the burst.