# HSC16aayt: Slowly evolving interacting transient rising for more than 100 days

## TL;DR

HSC16aayt is a Type IIn supernova with an unusually slow rise over 100 days and minimal brightness change over 400 days, observed by the Subaru HSC survey.

## Contribution

This study presents detailed observations of a slowly evolving Type IIn supernova with an exceptionally long rise time, expanding understanding of supernova diversity.

## Key findings

- Rise time exceeds 100 days
- Brightness variation within 0.6 mag over 400 days
- Located 5 kpc from host galaxy center

## Abstract

We report our observations of HSC16aayt (SN 2016jiu), which was discovered by the Subaru/Hyper Suprime-Cam (HSC) transient survey conducted as part of Subaru Strategic Program (SSP). It shows very slow photometric evolution and its rise time is more than 100 days. The optical magnitude change in 400 days remains within 0.6 mag. Spectra of HSC16aayt show a strong narrow emission line and we classify it as a Type IIn supernova. The redshift of HSC16aayt is 0.6814 +/- 0.0002 from the spectra. Its host galaxy center is at 5 kpc from the supernova location and HSC16aayt might be another example of isolated Type IIn supernovae, although the possible existence of underlying star forming activity of the host galaxy at the supernova location is not excluded.