TITLE: GCN CIRCULAR NUMBER: 20774 SUBJECT: LIGO/Virgo G275404: CNEOST optical observations DATE: 17/02/28 14:58:21 GMT FROM: Jinzhong Liu at Xinjiang Astronomical Observatory B. Li (PMO/CAS), D. Xu (NAO/CAS), H.B. Zhao, G.T. Zhaori, H. Lu, R.Q. Hong, L.F. Hu (PMO/CAS), T.M. Zhang, X. Zhou, H.X. Feng, Z.P. Zhu (NAO/CAS), J.Z. Liu, H.B. Niu, Y. Zhang, X. Zhang, G.X. Pu, S.G. Ma,T.Z. Yang, F.F. Song (XAO/CAS), J. Mao, J.M. Bai (YNAO/CAS) report on behalf of the Gravitational Wave Follow-Up Network by NAO-PMO-XAO-YNAO in China (GWFUNC): We have performed tiled observations of LIGO/Virgo G275404 (LVC, GCN 20738) using the 1-m Chinese Near Earth Object Survey Telescope (CNEOST) at Xuyi, Jiangsu, China. CNEOST has a FOV of 3.0x3.0 deg^2, and carried out observations during 10:44:55.9 - 14:44:22.4 UT and 19:46:14.6 - 21:47:47.6 UT on 2017-02-26 in the Sloan r-filter. The skymap coverage is at https://dl.dropboxusercontent.com/u/3665676/G275404/skymap20170226NEOST.pdf and the typical limiting magnitude is of m(r)~20.0 mag. Preliminary analysis doesn't reveal optical transient brighter than m(r)~17.5 mag that is positionally coincident with SDSS host galaxy whose spectroscopic or photometric redshifts is < 0.1.