This is fantastic! Congratulations Paolo !!!!
Peter: thank you for the alert and informations
Clearly a symbiotic with He II and perhaps [OIII] (He II is sufficient for symbiotic classification with Balmer lines in emission on a read giant continuum)
The amplitude of the variation before optical outburst is very low for a Mira
I open a page in the data base
Of course, coverage of the event is strongly recommended.
High resolution and Echelle spectra are expected.
Ranges : [OIII] 5007, NIII/CIII 4640 + He II, [Fe VII] 6087 and Raman OVI 6830
François