The curious case of 2018hna

2018hna is thought to be a type II supernova. It was discovered on the 22/10/2018 by Koichi Itagaki. However, so far it has had a strange development.

2018hna seems to have passed its maximum at around the 10/01/2019, about 80 days after its discovery. This is not the most straightforward type II development.

Light curve data collected by ASAS-SN, ZTF, and contributors to David Bishop’s supernova page all concur.

It has clear similarities in terms of light curve with 2005ci, which also reached its peak at about 82 days after discovery (data from Kait telescope and CCCP via OSC):

Their spectra show similitudes as well (data from Taddia et al. (2016), Yaron & Gal-Yam (2012), TNS via OSC):

I’m no expert so I can’t explain it (maybe from a blue supergiant?), but this supernova has peaked my interest. I’ve observed it a few times and will continue keeping an eye on it:

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