Optical spectrum of G2 obtained using MagE on the Magellan Clay Telescope. The corresponding 1σ error spectrum is shown in cyan at the bottom above the zero flux level (dash–dotted line), while a rectified 2D spectral image is presented at the top. Contaminating sky residuals are dotted out for clarification. We identify a faint emission line at 6644 Å, along with absorption features that are consistent with [O ii] and Ca ii H&K absorption doublet at z = 0.7818. We measure the redshift using a cross-correlation analysis with a linear combination of SDSS eigen spectra of galaxies. The best-fitting model template is shown as the red spectrum, which also displays matched absorption features due to the Balmer series.