A flux calibration device for the SuperNova Integral Field Spectrograph (SNIFS)

TL;DR

This paper introduces SCALA, a flux calibration device for SNIFS, which uses an array of mirrors and a tunable light source to achieve subpercent flux calibration accuracy for optical surveys.

Contribution

Development of a novel flux calibration system, SCALA, specifically designed for the SNIFS instrument, enabling highly precise calibration across UV to IR wavelengths.

Findings

Achieved subpercent flux calibration accuracy.

Demonstrated effective calibration over UV to IR range.

Enabled improved precision in optical survey measurements.

Abstract

Observational cosmology employing optical surveys often require precise flux calibration. In this context we present SNIFS Calibration Apparatus (SCALA), a flux calibration system developed for the SuperNova Integral Field Spectrograph (SNIFS), operating at the University of Hawaii 2.2 m telescope. SCALA consists of a hexagonal array of 18 small parabolic mirrors distributed over the face of, and feeding parallel light to, the telescope entrance pupil. The mirrors are illuminated by integrating spheres and a wavelength-tunable (from UV to IR) light source, generating light beams with opening angles of 1 degree. These nearly parallel beams are flat and flux-calibrated at a subpercent level, enabling us to calibrate our "telescope + SNIFS system" at the required precision.