A new outburst of the classical EXor V1118 Ori

ATel #12774; A. Giunta (ASI, Agenzia Spaziale Italiana, Italy), T. Giannini, S. Antoniucci, D. Lorenzetti, V. Testa, F. Vitali, D. Fugazza (INAF, Istituto Nazionale di Astrofisica, Italy), D. Licchelli (INFN, Università del Salento, Italy)
on 17 May 2019; 13:07 UT
Credential Certification: Teresa Giannini (teresa.giannini@inaf.it)

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In the framework of our EXORCISM project (EXOR OptiCal and Infrared Systematic Monitoring - Antoniucci et al. 2013 PPVI, Lorenzetti et al. 2007 ApJ 665, 1182; Lorenzetti et al. 2009 ApJ 693, 1056), we are following since many years the Pre-Main Sequence star V1118 Ori, one of the classical EXor sources (Audard et al. 2014 PPVI p.387). We have monitored both quiescence and bursting periods of V1118 Ori (ATEL # 514, 619, 1015, 8100) and an exhaustive record of its activity is given in Giannini et al. 2017 ApJ 839, 112. After a quiescence period of about 3 years, a significant increasing trend of its brightness was signaled by the ZTF light curve. The last available magnitude measured by the ZTF telescope on April 9 2019 was g = 15.2 with a brightness increase of more than two magnitudes compared to four months earlier. On May 9 2019 (MJD 58612.95508102), we observed V1118 Ori with the REM telescope at La Silla (Chile) in the optical bands, obtaining the following magnitudes: g = 14.62, r = 13.68, i = 13.20. The values are calibrated using SDSS catalog and errors are of the order of 0.1 mag in all bands. The observed colour [g-r] is 0.94 mag, which is consistent with the optical colours [V-R] of previous outbursts (Giannini et al. 2017 and references therein). The current magnitude rising speed is 0.018 mag/day, similar to that of the 2015 outburst (Giannini et al. 2017). This increasing trend most likely indicates the onset of a new outbursting phase. Unfortunately, for seasonal reasons, V1118 Ori will not be observable with ground-based telescopes in the next months. Spectro-photometric observations in the optical and near-IR range are strongly encouraged as soon as the target will be observable again.