Johnson-Cousins VRI Photometric Monitoring of AT2019abn
ATel #12506; Peter Pessev (GRANTECAN, IAC, ULL), David Jones (IAC, ULL), Ondrej Pejcha (Charles University), Olga Zamora (IAC, ULL), Matteo Monelli (IAC, ULL), Eduardo Mantero(IAC, ULL)
on 15 Feb 2019; 14:48 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Peter Pessev (peter.pessev@gtc.iac.es)
Subjects: Optical, Transient
We report photometric monitoring of the AT2019abn transient, discovered by Zwicky Transient Facility (ZTF; ATel #11266) on January 22nd, 2019. The object was classified as either a reddened SN impostor or a young Intermediate Luminosity Red Transient (ATel #12433). Observations were carried out through Johnson-Cousins VRI filters with the IAC80 telescope at the Observatorio del Teide, Tenerife, Spain, equipped with the CAMELOT optical CCD camera, covering 10.4x10.4 arcminutes FOV on the nights of 7th and 8th of February 2018 (~17/18 days after the transient discovery). The basic reduction of the data was carried out with the dedicated CAMELOT pipeline, photometry was performed with IRAF. Four stars with known VRI magnitudes in the field were used as internal standards. The observed magnitudes and colors of the object are listed below:
February 7th, 2019
V = 17.33+/-0.02
R = 16.52+/-0.01
I = 15.68+/-0.01
V-R = 0.81+/-0.02
V-I = 1.65+/-0.02
R-I = 0.84+/-0.01
February 8th, 2019
V = 17.24+/-0.01
R = 16.42+/-0.01
I = 15.64+/-0.01
V-R = 0.82+/-0.01
V-I = 1.60+/-0.01
R-I = 0.78+/-0.01
Overall we observe significant brightening of the transient with respect to the discovery reports on the Transient Name Server, as well as marginal brightening between the two epochs (more significant in the R and V filters).
Taking into account the distance to NGC5194 listed in McQuinn et al. 2017 (8.6+/-0.3 Mpc) and the extinction in the direction of the host (from NED) an absolute magnitude Mv=-12.4+/-0.1 is calculated for the transient in the current epoch. This is above the luminosity reported for most well-studied Luminous Red Novae (LRNe). The limited number of such objects observed up to date and the fact that most of the identified progenitor systems contained an evolved star, does not completely rule out the possibility of a main sequence merger. Another possible explanation based on the current absolute magnitude is an LBV eruption.
Presented data strongly emphasize the interesting nature of the transient and we plan to continue its monitoring. Further multi-wavelength observations are strongly encouraged.