Hi David,
From the sharp H alpha emission line in the spectrum (from the host galaxy) the redshift = ~0.04 which corresponds to ~170MPc distance. The spectrum is clearly a type 1a. At this distance a type 1a SN would reach ~16.9 at maximum, not allowing for any redenning. The ASAS-SN mag 17.2 does seem rather bright for 9-12 days before maximum but ages estimated from the spectra can be notoriously unreliable so it could be closer to maximum than this
Robin