TITLE:   GCN CIRCULAR
NUMBER:  23636
SUBJECT: GRB 190106A: NEXT-0.6m and Xinglong-2.16m photometric single powerlaw decay
DATE:    19/01/07 16:48:35 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.H. 
Liu (XAO) report:

We monitored the optical afterglow of GRB 190106A (e.g., Sonbas et al., 
GCN 23615) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, 
China and the Xinglong-2.16m telescope.

The observations of NEXT-0.6m started at 13:57:21 UT on 2019-01-06 
(i.e., 0.38 hr post-burst) and ended at 19:48:25 UT on 2019-01-06 (i.e., 
5.97 post-burst), with a series of 60s, 90s, 120s, 200s, and 300s 
exposures in the R-band. The afterglow had R=16.9+/-0.1 mag at the 
beginning, and rather smoothly decayed to R=19.1+/-0.1 mag at the end, 
calibrated with nearby SDSS stars.

The Xinglong-2.16m observations were carried out at 12:54:46 UT on 
2019-01-07, i.e, 23.33 hr post-burst, with 5x360s in the R-band. The 
afterglow has decayed to R=19.9+/-0.1 mag, calibrated with the same 
reference stars.

The joint NEXT-0.6m and Xinglong-2.16m dataset shows that so far the 
afterglow R-band lightcurve has been decaying, and following a single 
powerlaw of F ~ t^-alpha, where alpha~0.64.