These days this object got even brighter, attracted enough to try a 2nd reproduce:
Exposure composition: 3 x 20 min caught the object in good quality (but windy conditions), + 2 x 20 min weighted as 0.5 for being the object low. (All with bin 1x1, just to make the noise level really visible.)
The Na I 5890 absorption seems definitely there and continuum slope matching with previous, but there might be a (missing?) feature of Mg II 2700A redshifted to 5700A according to 1606.07836.pdf.
- there is a large emission of Mg II ~ 5700A from 2012 and 2015, if I read the page 3.3 correctly! (fixme)
And an older event, with no emission: http://adsabs.harvard.edu/full/1967SvA....10..964P
Explanation would be appreciated about why to see Mg II emission sometimes, and not in the other cases.
Attaching result spectra with and without sky background removal (to see where can be pollution).