TITLE:   GCN CIRCULAR
NUMBER:  26483
SUBJECT: LIGO/Virgo S191216ap: GRAWITA Loiano observations of HAWC error region
DATE:    19/12/18 10:44:24 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi@inaf.it>

A. Rossi, M. Dadina, E. Maiorano, R. Gualandi (INAF-OAS), P. D'Avanzo, A. Melandri (INAF-OABr), M.T. Botticella (INAF-OAC), and E. Brocato (INAF-Abruzzo) report on behalf of GRAWITA

We observed the inner part of the error box obtained by the HAWC collaboration (Martinez-Castellano GCN #26472) during the follow-up of the GW trigger S191216ap (GCN #26454) with the 152cm Cassini Telescope at Loiano Observatory. The pointing was performed using the R filter. Four 10min exposures have been obtained starting at 18:12:29 on 2019-12-17 (UT), covering a mosaic of ~20'x20'. The observation was affected by bad seeing (4"), low elevation, and passing clouds.

In preliminary analysis, assuming R=14.4 for the star at coordinates RA,DEC(J2000) 21:33:59, +05:16:21.5), for the galaxy #1 reported by Singer et al (GCN #26479) we measure R=16.6+-0.1. This is consistent with r=16.5 reported in SDSS catalog, within the photometric system and filter differences.

No other obvious candidate is visible down to R=18.5 mag and in comparison to DSS2 survey.

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