Multi-star calibration in starphotometry

• Published in: Atmospheric Measurement Techniques
• Main Authors: L. Ivănescu, N. T. O'Neill
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: Environmental engineering; TA170-171; Earthwork. Foundations; TA715-787; Arctic; Eureka
• Online Access: https://doi.org/10.5194/amt-16-6111-2023; https://doaj.org/article/bf43796f5758442cbf4dce4621a16f28

We explored the improvement in starphotometry accuracy using a multi-star Langley calibration in lieu of the more traditional one-star Langley approach. Our goal was a 0.01 calibration-constant repeatability accuracy, at an operational sea-level facility such as our Arctic site at Eureka. Multi-star calibration errors were systematically smaller than single-star errors and, in the mid-spectrum, approached the 0.01 target for an observing period of 2.5 h. Filtering out coarse-mode (supermicrometre) contributions appears mandatory for improvements. Spectral vignetting, likely linked to significant UV/blue spectrum errors at large air mass, may be due to a limiting field of view and/or sub-optimal telescope collimation. Starphotometer measurements acquired by instruments that have been designed to overcome such effects may improve future star magnitude catalogues and consequently starphotometry accuracy.