TITLE: GCN CIRCULAR NUMBER: 21833 SUBJECT: LIGO/Virgo G298048 GRAWITA: VST-ESO PARANAL follow up of SSS17a in NGC4993. DATE: 17/09/06 15:07:27 GMT FROM: Aniello Grado at INAF-OAC A. Grado (INAF-OAC), F. Getman (INAF-OAC), L. Limatola (INAF-OAC), E. Cappellaro (INAF-OAPD), M. Branchesi (GSSI), S. Covino (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Melandri (INAF-OAB), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), S. Ascenzi (INAF-OAR), S. Benetti (INAF-OAPD), M.T. Botticella (INAF-OAC), S. Campana (INAF-OAB), V. D'Elia (INAF-ASDC), D. Fugazza, M. Lisi (INAF-OAR), G. Greco (Urbino University/INFN Firenze), L. Nicastro (INAF-IASF Bo), E. Palazzi (INAF, IAFS Bo), E. Pian (INAF, IAFS Bo), S. Piranomonte (INAF-OAR), L. Pulone (INAF-OAR), A. Rossi (INAF-IASF Bo), P. Schipani (INAF-OAC), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L . Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report: Observations of 1 square degrees of the skymap of the Advanced LIGO and Virgo trigger G298048 (LVC GCN Circ. 21509, 21513) were performed with the VLT Survey Telescope (VST - Proposal ID ESO 099.D-0191) at ESO-Paranal equipped with OMEGACAM. The observations are centered on the galaxy NGC4993. The images were taken in the i_SDSS filter with a total exposure of 1200s. The observations started at 2017-08-31T 23:22:12.442 UTC and finished at 2017-08-31T 23:39:26.585. The Optical Transient (OT) is not visibile in the coadded image. The completeness at 50% for point-like sources is 22.53 AB mag. Automatic data reduction with the VSTTube pipeline (Grado et al. 2012 Mem.SAIt 19, 362 ) was completed. We acknowledge excellent support from the ESO User Support Department and from ESO observing staff in Paranal.