Hi Paul,
It has not maxed out yet so if it follows the normal Ia light curve will likely be around mag 16 in a month’s time so still an easy imaging target.
Note my original comment on mag 18 being out of range for amateurs referred specifically to spectroscopy, not imaging. With my ALPY 200 the target has to be about 6.5 mags brighter for spectroscopy than for a conventional photometry image. The big advantage with slit spectroscopy though is most of the sky background is kept out by the slit so you can get away with much higher levels of light pollution. My limiting spectroscopic magnitude is ~17.5 which corresponds to mag 24 for photometry. I would need much darker skies to do photometry that deep in a conventional image though.
Cheers
Robin