NIRPS Sun-as-a-Star Observations

The newly commissioned Near Infra Red Planet Searcher (NIRPS) spectrograph will offer a unique opportunity of studying stellar activity at high resolution with simultaneous near-infrared and optical wavelengths since it is planned to work in unison with the HARPS spectrograph, both located at the ESO 3.6m telescope in La Silla, Chile. Furthermore, during day-time operations the two instruments are fed by the solar tracker HELIOS which delivers high S/N, disk-integrated Sun-as-a-Star observations.

In this work, we present initial results from HELIOS during the last months of NIRPS commissioning and first few months of official operations. The 1-minute cadence of HELIOS provides a wealth of spectra with which stellar activity, telluric correction and instrumental systematics can be well monitored at the spectral level as well as in extracted radial velocities. Finally, we investigate the chromaticity of stellar activity, such as the wavelength-dependent effect of Zeeman broadening.