TITLE: GCN CIRCULAR NUMBER: 20416 SUBJECT: LIGO/Virgo G268556/GW170104: TNG observations of ATLAS17aeu DATE: 17/01/10 11:27:39 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), E. Palazzi (INAF-IASF Bo), A. Rossi (INAF-IASF Bo), E. Cappellaro (INAF-OAPD), S. Covino (INAF-OAB), V. D'Elia (INAF-ASDC), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L. Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), L. Di Fabrizio, G. Mainella (INAF/TNG), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report: We observed the position of the transient ATLAS17aeu (Tonry et al., LVC Circ. 20382) with the TNG 3.6m telescope located in Canary Islands equipped with the DOLORES camera in imaging mode. Observations consisted in 8x120s exposures in the I-band. The transient is clearly detected with a magnitude I = 22.5 +/- 0.3 (Vega) at a mid time of 02:14:12 UT on 2017 Jan 8. [GCN OPS NOTE(10jan17): Per author's request, the time in the last sentence was changed from 14:12" to "02:14:12".]