TITLE: GCN CIRCULAR NUMBER: 25117 SUBJECT: LIGO/Virgo S190718y: No counterpart candidates in CNEOST DATE: 19/07/20 05:11:09 GMT FROM: Bin Li at PMO Bin Li, Hai-bin Zhao (PMO),Dong Xu, Zi-pei Zhu, Bang-Yao Yu,Tian-meng Zhang, Xu Zhou,Chen-zhou Cui, Hui-juan Wang(NAOC), Xue-feng Wu, Zhi-ping Jin, Tian-rui Sun, Hao Lu, Ge-tu Zhaori, Ren-quan Hong, Long-fei Hu (PMO), Xiao-feng Wang, Wen-xiong Li (THU),Li-fan Wang (PMO/TAMU), Jin-zhong Liu (XAO), Ji-rong Mao, Jin-ming Bai (YNAO), report on behalf of the CNEOST collaboration. We conducted optical imaging observations for gravitational wave alert with Chinese Near Earth Object Survey Telescope (CNEOST) at Xuyi astronomical station in Jiangsu Province, China (32.75N, 118.47E). The information of observations and preliminary results are listed below. Alert: LIGO/Virgo S190718y (GCN 25087) StartTime (UT): 2019-07-19T12:41:19.523 EndTime (UT): 2019-07-19T18:19:52.108 Skycover (Square Degree): 639.0 Telescope FoV (Square Degree):9.0 #id CentRA(D) CentDEC(D) LimiteMag3_sig 5_sig 10_sig Filter 1 208.869080 -6.786121 20.178 19.181 18.177 SR 2 207.332977 -1.223906 20.265 19.261 18.376 SR 3 210.666458 -4.041420 20.254 19.265 18.329 SR 4 216.043030 -9.596825 20.185 19.217 18.256 SR 5 217.903732 -15.211738 19.997 18.994 17.997 SR 6 215.287582 -12.401288 19.966 19.002 18.058 SR 7 210.364441 -9.628950 20.049 19.056 18.076 SR 8 207.832382 -4.038251 20.262 19.259 18.324 SR 9 210.156891 -1.234565 20.318 19.323 18.407 SR 10 211.684143 -6.830252 20.100 19.149 18.213 SR 11 220.779205 -15.240459 19.922 18.975 18.015 SR 12 208.869080 -6.786121 20.178 19.181 18.177 SR 13 210.156891 -1.234565 20.318 19.323 18.407 SR 14 211.684143 -6.830252 20.100 19.149 18.213 SR 15 216.043030 -9.596825 20.185 19.217 18.256 SR 16 220.779205 -15.240459 19.922 18.975 18.015 SR 17 215.287582 -12.401288 19.966 19.002 18.058 SR 18 306.185486 23.842829 19.291 18.356 17.303 SR 19 305.508270 29.443697 19.330 18.419 17.469 SR 20 307.824493 35.063766 19.557 18.656 17.621 SR 21 312.000488 37.857952 19.497 18.596 17.475 SR 22 314.533600 32.205532 19.391 18.475 17.317 SR 23 308.675293 29.416243 19.335 18.435 17.488 SR 24 305.508270 29.443697 19.330 18.419 17.469 SR 25 307.824493 35.063766 19.557 18.656 17.621 SR 26 312.000488 37.857952 19.497 18.596 17.475 SR 27 314.533600 32.205532 19.391 18.475 17.317 SR 28 307.880554 32.229843 19.462 18.527 17.523 SR 29 307.028320 26.640734 19.367 18.468 17.454 SR 30 304.380890 35.047928 19.489 18.588 17.431 SR 31 309.932098 40.646816 19.639 18.729 17.591 SR 32 311.208282 35.018509 19.474 18.566 17.400 SR 33 314.533600 32.205532 19.391 18.475 17.317 SR 34 307.880554 32.229843 19.462 18.527 17.523 SR 35 308.223480 1.420728 18.660 17.754 16.915 SR 36 309.839081 9.804000 18.793 17.888 16.974 SR 37 312.659424 9.800121 18.743 17.836 16.908 SR 38 309.607025 18.222225 18.980 18.071 17.074 SR 39 306.655151 18.243509 19.021 18.088 17.056 SR 40 312.075226 21.049301 19.014 18.083 17.079 SR 41 318.466370 18.222324 18.949 18.017 16.982 SR 42 313.774658 15.433895 19.007 18.055 17.062 SR 43 322.525757 15.434681 18.984 18.004 16.987 SR 44 315.705475 12.637063 18.935 18.010 17.033 SR 45 321.214417 9.811152 18.731 17.783 16.832 SR 46 316.081055 7.014183 18.795 17.842 16.921 SR 47 311.754395 4.228014 18.686 17.775 16.887 SR 48 313.776703 -1.401701 18.251 17.366 16.533 SR 49 308.223480 1.420728 18.660 17.754 16.915 SR 50 309.839081 9.804000 18.793 17.888 16.974 SR 51 310.891296 15.423524 18.974 18.075 17.106 SR 52 306.073547 21.013973 19.140 18.213 17.172 SR 53 315.045715 21.008123 18.907 17.995 17.038 SR 54 315.521973 18.200771 18.994 18.056 17.059 SR 55 316.691681 15.434895 18.960 18.034 17.055 SR 56 322.525757 15.434681 18.984 18.004 16.987 SR 57 318.607544 12.637962 18.854 17.920 16.948 SR 58 318.352875 9.810987 18.740 17.819 16.888 SR 59 318.875336 7.004980 18.767 17.841 16.919 SR 60 314.550995 4.224255 18.699 17.756 16.866 SR 61 313.830048 1.406936 18.628 17.684 16.804 SR 62 308.185730 -1.344688 18.493 17.572 16.766 SR 63 310.401428 7.007415 18.797 17.879 16.966 SR 64 312.835144 12.623907 18.896 17.977 17.014 SR 65 309.607025 18.222225 18.980 18.071 17.074 SR 66 306.073547 21.013973 19.140 18.213 17.172 SR 67 318.466370 18.222324 18.949 18.017 16.982 SR 68 313.774658 15.433895 19.007 18.055 17.062 SR 69 319.574982 15.416553 18.978 18.053 17.063 SR 70 321.712860 7.031455 18.669 17.751 16.811 SR 71 325.777649 26.589394 15.121 14.167 13.528 SR Detailed data analysis is still in progress and any interesting transients will be reported later. The new resulte will available at http://www.cneost.org/opem/list.php?gdate=2019-07-19 We aslo detect the source — MASTER OT J203053.79+384020.1 / AT2019lly (Lipunov et al., GCN #25105) in our survey, which are labeled OPEM-19vs ( http://www.cneost.org/opem/findname.php?opemname=OPEM-19vs ). And, a point source (r=16.32 +- 0.04 ,observed 2017-11-03) is present in the archive catalog of CNEOST at the location of AT2019lly.