Exploring the potential of a VIPA spectrograph on-sky

Abstract

We developed a near-IR, échelle-like, fiber-fed spectrograph demonstrator using a VIPA instead of an échelle grating, achieving a high spectral resolution (R=80,000) over a 220 nm range with 38% efficiency (from fiber exit to H2RG detector). Designed to characterize exoplanets at high spectral resolution with an XAO instrument, it was installed in February 2025 for on-sky demonstration at the 1.52m Haute-Provence Observatory telescope, and coupled via the PAPYRUS AO system. We observed reference and feature-rich stars to test the instrument’s H-band transmission and spectral fidelity/stability. K-band tests are planned for early 2026. This presentation covers the current design, calibrations, and on-sky performance, as well as the data reduction pipeline and ETC we developed. We also detail the attempted observation of HR8799c, including a comprehensive SNR analysis to identify limitations and extrapolate to larger telescopes. Finally, we introduce the design of an HK-band version.