LIGO/Virgo G298048: further REM optical/NIR observations of candidate in NGC 4993

We continued the optical/NIR follow-up monitoring of the LIGO/Virgo GW trigger G298048 (LVC GCN Circ. 21509, 21513) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile) by performing targeted observations of catalogued galaxies in the LVC skymap. The observations were carried out from 23:31 UT on 2017 Aug 18 to 01:18 UT on on 2017 Aug 19, simultaneously in the g, r, i, z, J, H and K bands. We clearly detect in all bands the optical source reported by Coulter et al. (LVC GCN 21529, 21567), Allam et al. (LVC GCN 21530), Yang et al. (LVC GCN 21531, 21579), Melandri et al. (LVC GCN 21532), Arcavi et al. (LVC GCN 21538, 21581), Nicholl et al. (LVC GCN 21541, 21580), Tanvir & Levan (LVC GCN 21544), Evans et al. (LVC GCN 21550), Simon et al.(LVC GCN 21551), Singer et al. (LVC GCN 21552), Chambers et al. (LVC GCN 21553, 21590), wolf et al. (LVC GCN 21560), Yoshida et al. (LVC GCN 21561, 21586), Kilpatrick et al. (LVC GCN 21583) and Wieseman et al. (LVC GCN 21584). With respect to our previous epoch (Melandri et al. LVC GCN 21532), preliminary analysis shows that the source is significantly fainter in the g-band and displays no variation in the r-band. Analysis and calibration is ongoing and further observations are planned.