Angular correlation of the stellar scintillation on large telescopes

TL;DR

This paper investigates how stellar scintillation correlates between close stars on large telescopes, using data from the Northern Caucasus to predict correlation scales and potential noise reduction in photometry.

Contribution

It derives correlation functions for stellar scintillation based on optical turbulence data, enabling improved noise mitigation strategies for large telescope photometry.

Findings

Median correlation radius of 20 arcsec for Kolmogorov turbulence.

Scintillation noise can be reduced up to 8 times using comparison star ensembles.

Correlation calculations can be adapted for any large telescope with known turbulence profiles.

Abstract

The stellar scintillation is one of the fundamental limitation to the precision of ground-based photometry. The paper examines the problem of correlation of the scintillation of two close stars at the focus of a large telescope. The derived correlation functions were applied to data of the long-term study of the optical turbulence (OT) in the Northern Caucasus with MASS (Multi-Aperture Scintillation Sensor) instrument to predict the angular correlation of the scintillation at the Sternberg institute 2.5 m telescope currently in construction. A median angular radius of the correlation as large as 20 arcsec was found for the case of Kolmogorov OT. On the basis of the obtained relations we also analyze the correlation impact in ensemble photometry and conjugate plane photometry. It is shown that a reduction of the scintillation noise up to 8 times can be achieved when using a crowded ensemble of comparison stars. The calculation of the angular correlation can be repeated for any large telescope at the site where the OT vertical profiles are known.