LIGO/Virgo G268556: Additional GROWTH follow up observation of iPTF Optical Transient Candidates

We observed the field of the optical candidate reported by Singer et al. (LVC GCN 20401) with the 50cm Japanese telescope at Akeno Observatory (Japan) and the 40cm Telescope (SLT) with Apogee CCD at Lulin Observatory (Taiwan). We obtained the g, V, R and I bands image on 2017-01-09 and 2017-01-10 (UTC). The observed objects are listed below (3-sigma upper limits). We note that iPTF17fu, iPTF17fs, iPTF17ft, iPTF17fw, iPTF17gr, iPTF17gv and iPTF17gw contained the host galaxy but subtraction of host galaxy were not applied. #Time(UT) exposure[sec] ra[deg.] dec[deg.] V[mag.] V-error Name 2017-01-09T18:13:02 300.0 162.900034 +69.833971 18.99 0.13 iPTF17fs #Time(UT) exposure[sec] ra[deg.] dec[deg.] g[mag.] g-error R[mag.] R-error I[mag] I-error Name 2017-01-09T11:40:51.95 660.0 162.900034 +69.833971 >18.7 -- >19.0 -- >18.7 -- iPTF17fs 2017-01-09T16:31:03.65 2580.0 156.366148 +71.757620 16.46 0.07 15.46 0.02 14.97 0.03 iPTF17fw 2017-01-09T15:12:28.36 2640.0 159.042893 +69.146836 >19.1 -- >18.9 -- >18.5 -- iPTF17ge 2017-01-09T19:58:36.97 2040.0 199.058226 +76.521298 19.0 0.2 18.4 0.2 17.9 0.4 iPTF17gs 2017-01-09T12:48:30.17 2340.0 176.227516 +82.619152 16.52 0.07 15.49 0.03 14.87 0.03 iPTF17gv 2017-01-09T18:31:04.09 1380.0 178.409537 +72.864968 17.6 0.2 16.59 0.09 15.89 0.04 iPTF17gw 2017-01-09T19:07:24.90 1560.0 194.925476 +75.016124 19.9 0.2 >19.7 -- >18.7 -- iPTF17hh 2017-01-09T17:31:38.92 1920.0 180.885869 +72.050360 18.7 0.3 18.7 0.4 18.5 0.5 iPTF17hi 2017-01-09T19:48:39.40 480.0 191.763759 +76.839773 19.0 0.2 18.5 0.2 >18.1 -- iPTF17gt 2017-01-09T13:02:59.53 480.0 165.400920 +68.097753 >17.3 -- >18.0 -- >17.4 -- iPTF17hc 2017-01-10T18:52:33.53 1980.0 201.323053 +78.426314 16.23 0.09 15.21 0.03 14.84 0.03 iPTF17ft 2017-01-10T20:41:03.31 300.0 235.823172 +74.750334 18.8 0.3 17.6 0.2 17.0 0.2 iPTF17gm 2017-01-10T20:03:36.84 1920.0 232.045095 +74.611299 19.5 0.4 18.8 0.3 17.0 0.2 iPTF17gn 2017-01-10T19:41:27.53 480.0 195.818782 +80.173138 >18.9 -- >18.5 -- >18.0 -- iPTF17hf 2017-01-10T12:35:41.66 1140.0 192.417627 +80.149750 17.52 0.07 16.14 0.03 15.54 0.03 iPTF17fu 2017-01-10T18:12:54.94 2100.0 193.895770 +79.226903 17.51 0.04 16.22 0.02 15.64 0.02 iPTF17gr 2017-01-10T15:12:41.65 2340.0 194.101611 +78.204729 19.6 0.3 18.6 0.2 iPTF17gu Observations of this source were taken as part of the GROWTH network ( http://growth.caltech.edu).