Table B.1.

Parameters derived from the GRAVITY fits of the final model. ρ is the separation and PA is the position angle. The position of the primary was fixed at (0,0). In this best-fitting model both stars are modelled as uniform disks with 0.2 mas diameters, such that they appear as point sources. f_K is the flux ratio of the dimmer star in the K band in reference to the flux of the normalised brightest star (fixed to 1 during the fitting process). f_line is the flux of the Brγ line with respect to the continuum, w_line is the full-width at half maximum (FWHM) of the line and λ_line is its wavelength.

Mean Julian Date		fK	ρ	PA	fline	wline	λline
(MJD)			(mas)	(°)		(nm)	(μm)
59463.117	1.243	0.599±0.017	1.14±0.02	58.1±1	1.06±0.01	2.422±0.006	2.1661055±0.000002
59476.031	1.321	0.516±0.019	1.16±0.03	−167±0.8	0.892±0.001	2.643±0.004	2.166367±0.000001