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

摘要

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