Some comparisons between 4 spectra taken in december: 3 before the periastron, 1 after (the 25th) with an eshel spectrograph.
With the eshel, the most difficulty is to merge the spectra of several orders in order to have the full width of the band CIII-CIV and a good continnuum specially at each end of each order.
Difficult also with the weather not so find in the south est of France actually, (not a really clear sky)
Here's a result first with 3 orders merge (order #40, #39 and #38)
And another with only #39 order
The last spectrum (in red) taken the 25th show an evolution with others spectra taken before the periastron.