Fig. 2

Typical nightly mean spectrum obtained from NIRAS measurements on May 29 and May 6, 2018. a A spectra with the 600-lpmm grating and a center wavelength of 1504 nm. b A spectra with the 150-lpmm grating and a center wavelength of 1371 nm. It should be noted that data near the edge on a short wavelength side is not reliable, and therefore not used for quantitative discussions