Multi-star calibration in starphotometry

• Published in: Atmospheric Measurement Techniques
• Main Authors: Ivănescu, Liviu, O'Neill, Norman T.
• Format: Text
• Language: English
• Published: 2023
• Subjects: Arctic; Eureka
• Online Access: https://doi.org/10.5194/amt-16-6111-2023; https://amt.copernicus.org/articles/16/6111/2023/

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.