TITLE: GCN CIRCULAR NUMBER: 21766 SUBJECT: LIGO/Virgo G299232: GRAWITA Campo Imperatore optical observations DATE: 17/08/30 12:15:54 GMT FROM: Enzo Brocato at INAF-OA Roma A. Giunta, A. Di Paola, M. Centrone, N. Napoleone (INAF-OAR), G. Greco (Urbino University/INFN Firenze), M. Branchesi (GSSI), 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), E. Cappellaro (INAF-OAPD), S. Covino, P. D’Avanzo (INAF-OAB), V. D'Elia (INAF-ASDC), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR),A. Melandri (INAF-OAB), L. Nicastro, E. Palazzi, E. Pian (INAF-IASF Bo), S. Piranomonte (INAF-OAR), L. Pulone (INAF-OAR), A. Rossi (INAF-IASF Bo), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L . Tomasella (INAF-OAPD), S. Yang (INAF-OAPD) and E. Brocato (INAF-OAR) on behalf of GRAvitational Wave Inaf TeAm (GRAWITA) report: We carried out observa <>tions of LIGO/Virgo G299232 (LVC, GCN 21693) starting 6.7 hours after the trigger with the 0.9m/0.6m Schmidt telescope located at the Campo Imperatore Observatory (Italy). The observations were taken in the r-sloan band on 2017-08-25 and 2017-08-26 starting respectively at 19:55:57 UT and 20:15:21 UT with relatively good sky conditions. Each night the covered area of ~60 square degrees captured a containment probability of ~7,2% of the cWB map (LVC, GCN 21693). The area is divided in 5 blocks of 3x3 pointings, each pointing covering 1.15x1.15 square degrees of the sky with 3x120 sec exposure time. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky ) starting from the high probability region of the bayestar skymap and taking into account the airmass and relative density of nearby galaxies. The first block covers an area where GW skymap overlaps neutrino detection. The 3x3 square degrees pointing blocks are centered on the following coordinates RA, Dec (J2000) and UT times: 1 28.27 44.81 2017-08-25T20:32:06 2017-08-26T20:52:17 2 31.87 40.28 2017-08-25T21:53:52 2017-08-26T22:15:13 3 30.22 37.12 2017-08-25T23:14:13 2017-08-26T23:38:52 4 33.39 43.42 2017-08-26T01:41:21 2017-08-27T01:09:37 5 34.08 46.50 2017-08-26T02:44:46 2017-08-27T02:46:04 The limiting magnitude is r ~20.0-22.0 as a function of the observing conditions. Analysis of the images is ongoing.