TITLE: GCN CIRCULAR NUMBER: 20736 SUBJECT: LIGO/Virgo G274296: GRAWITA-Campo Imperatore observation DATE: 17/02/25 17:06:09 GMT FROM: Enzo Brocato at INAF-OA Roma A. Giunta, A. Di Paola, M. Centrone, N. Napoleone, P. Tedesco (INAF-OAR), G. Greco, M. Branchesi (Urbino University/INFN Firenze), S. Covino (INAF-OAB), L. Amati (INAF-IASF Bo), L. A. Antonelli, S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), S. Campana (INAF-OAB), E. Cappellaro (INAF OAPd), P. D'Avanzo (INAF-OAB), V. D'Elia (INAF-ASDC), F. Getman, A. Grado, L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), A. Melandri (INAF-OAB), L. Nicastro, E. Palazzi (INAF-IASF Bo), E. Pian (SNS-Pisa), S. Piranomonte, 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, S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm (GRAWITA) report: We carried out observations of LIGO/Virgo G274296 (LVC, GCN 20689) with the 0.9m Schmidt Telesope located at the Campo Imperatore Observatory (Italy). The observations were taken in the r-sloan band on 2017-02-19 starting at 01:21:55 UT relatively good sky conditions. The covered area captured a containment probability of ~5% and was chosen to maximize the number of local (< 30 Mpc) galaxies to be observed. The area is divided in 4 blocks of 3x3 pointing each of them of covering 1.15x1.15 square degrees of the sky and 5x90 sec exptime each. 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 pointings are centered on the following UT times, coordinates RA, Dec (J2000) and observed area: 2017-02-19T21:22:04 137.106 5.926 1.15x1.15 square degrees 2017-02-19T04:16:28 166.43 28.33 1.15x1.15 square degrees 2017-02-19T04:10:14 162.47 28.01 1.15x1.15 square degrees 3x3 pointing blocks 2017-02-19T02:54:33 157.481 28.318 ~3x~3 square degrees 2017-02-19T01:21:55 157.34 23.988 ~3x~3 square degrees 2017-02-19T23:35:11 157.22 20.9 ~3x~3 square degrees 2017-02-19T21:33:26 153.709 21.68 ~3x~3 square degrees The limiting magnitude is r ~ 20.5. Analysis of images is ongoing. -- Enzo Brocato INAF - Osservatorio Astronomico di Roma Via di Frascati 33, I-00040 Monteporzio Catone, Italy Phone: +39 0694286438 Fax: +39 06 9447243 skype: enzo.brocato URL: SpoT Group Homepage: www.oa-teramo.inaf.it/SPoT