TITLE:   GCN CIRCULAR
NUMBER:  23538
SUBJECT: GRB 181213A: HMM-0.5m, NEXT-0.6m, CNEOST-1m optical observations
DATE:    18/12/14 11:07:54 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu, D. Xu (NAOC), X. Zhang, J.H. Liu (XAO), B. Li, H.B. Zhao 
(PMO), X. Gao (Urumqi No.1 Senior High School), M. Yang (XJTS) report:

We observed the field of GRB 181213A (Evans et al., GCN 23525; Lipunov 
et al., GCN 23526; Hu et al., GCN 23527) using the HMT-0.5m telescope 
located at Gao-Ya-Zi, Xinjiang, China at 14:32:10 on 2018-12-13, i.e., 
1.57hr after the Swift trigger, and obtained 45x90s, 1x120s, 1x180s 
unfiltered frames.

The afterglow is clearly detected in part of the HMT images, and 
preliminary results are as follows:

Date	            Tstart (UT)	T-T0(hr)	Exp.(s)	   Mag(R)
2018-12-13     14:55:00	1.95	        3x90	        18.0+/-0.1
2018-12-13     15:00:25	2.03	        5x90	        18.1+/-0.1

We also used the NEXT-0.6m telescope located at Nanshan, Xinjiang, at 
14:49:04 UT on 2018-12-13, i.e., 1.85hr after the Swift trigger and 
obtained 5x90s R-band frames under  cloudy weather. The afterglow is not 
detected down to a limiting magnitude of R~17 mag, calibrated with the 
SDSS field.

Additionally, the CNEOST-1m telescope started observation at 21:43:36 on 
2018-12-13, i.e., 8.76hr after the Swift trigger and we obtained 15x90s 
VR-band frames. The afterglow is not detected down to a 3-sigma upper 
limit of ~20.3 mag.