Comparison of LGS-AO integral field spectroscopy of the Galactic Centre between ERIS (June 2022) and SINFONI (April 2008). The quality of the 40 min ERIS data (centre left), which were taken in 1.″0 seeing, are comparable to the very best 210 min SINFONI data taken in 076 seeing, as evidenced by the diffraction rings that can be seen around S2 and S4. This relatively short integration is sufficient to show clear detections of the He I and Brγ absorption lines in S2 (centre right), and hence to measure a precise velocity that closely matches that predicted from the model of its orbit (far right; adapted and updated from GRAVITY Collaboration 2019).