Pan-STARRS1 Discovery of Two Ultra-Luminous Supernovae at z ~ 0.9

Understand

We present the discovery of two ultra-luminous supernovae (SNe) at z ~ 0.9 with the Pan-STARRS1 Medium-Deep Survey.

• These SNe, PS1-10ky and PS1-10awh, are amongst the most luminous SNe ever discovered, comparable to the unusual transients SN 2005ap and SCP 06F6.
• Like SN 2005ap and SCP 06F6, they show characteristic high luminosities (M_bol ~ -22.5 mag), blue spectra with a few broad absorption lines, and no evidence for H or He.
• We have constructed a full multi-color light curve sensitive to the peak of the spectral energy distribution in the rest-frame ultraviolet, and we have obtained time-series spectroscopy for these SNe.