INT WFC multi-band photometric follow up of the superluminous supernova SN 2018ffj

ATel #12344; E. M. Garcia-Zamora (ULL), A. Hernandez-Garcia (ULL & IAC), M. Mallorquin (ULL), A. Alvarez-Hernandez (ULL), A. Alvarez-Saavedra (ULL), P. Carro-Portos (ULL), E. A. Diaz-Suarez (ULL), R. M. Doblas-Cabezas (ULL), M. Fernandez-Torreiro (ULL), J. E. Mendez-Delgado (ULL & IAC), D. Moral-Pombo (ULL), M. A. Nuñez-Cagigal (ULL & IAC), G. Panizo-Espinar (ULL), J. Sanchez-Sierras (ULL), D. SanJulian-Jacques (ULL), H. Villegas-Beberide (ULL), L. Monteagudo (ING), and I. Perez-Fournon (ULL & IAC)
on 31 Dec 2018; 12:25 UT
Credential Certification: Ismael Perez-Fournon (ipf@iac.es)

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We report multi-band photometry of the superluminous supernova SN 2018ffj (= MASTER OT J023059.78-172027.1) (= GRB 180810.28) (= ATLAS18tec) based on CCD images taken with the Wide Field Camera of the Isaac Newton Telescope (Observatorio del Roque de los Muchachos, La Palma), from 2018 Oct 13.080 UT to 13.085 UT. This supernova was discovered on 2018/08/07.574 by the ATLAS survey and reported to TNS by J. Tonry et al. It was also detected by the MASTER Global Robotic Net (O. Gress et al., ATel # 11935, and Lipunov et al., GCN 23126) and classified as a Type SLSN-I supernova at a redshift of z=0.234 by ePESSTO (E. Callis et al., ATel #11969) .

We report here the SN position, based on the INT images, calibrated using the Gaia DR2 catalog: RA (J2000) = 02:30:59.790, Dec (J2000) = -17:20:26.84.

The INT Wide Field Camera magnitudes of SN 2018ffj, calibrated using Pan-STARRS1 are:

g = 20.27 +/- 0.02 (2018 Oct 13.086), exposure time = 120 seconds
r = 19.67 +/- 0.03 (2018 Oct 13.081), exposure time = 120 seconds
i = 19.75 +/- 0.03 (2018 Oct 13.0.84), exposure time = 120 seconds

The host galaxy is visible on SDSS (SDSS J023059.77-172026.8 ) and DECaLS DR7 images (see the figure linked below) but is not well detected in the Pan-STARRS1 DR1 images.

Info on the SN host galaxy (SDSS DR15).

SDSS J2000 position of the host galaxy: RA (J2000) = 02:30:59.77, Dec (J2000) = -17:20:26.82. We don't find any significant offset between the SN and host galaxy positions.

The SDSS magnitudes of the host galaxy (SDSS J023059.77-172026.8) are 23.99 +/- 0.84, 24.40 +/- 0.48, 22.53 +/- 0.18, 22.69 +/- 0.28 and 22.01 +/- 0.50 in the SDSS u, g, r, i, and z filters, respectively.

The apparent and absolute magnitudes of the SN close to the peak of the light curve were 18.06 and -22.12, respectively (in the ATLAS cyan filter, see info at the Open Supernova Catalog). At the time of maximum emission, the SN was about 4.5 magnitudes brighter than its host galaxy.

Based on observations made with the Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

We thank David Bishop for his wonderful compilation of extragalactic novae and supernovae.

Isaac Newton Telescope Wide Field Camera r-band image