Low frequency seeing and solar diameter measurements

TL;DR

This paper investigates how low frequency atmospheric seeing affects solar diameter measurements, revealing that image motion and stretching occur even at very low frequencies, impacting measurement accuracy.

Contribution

It provides evidence of low frequency image motion and stretching affecting solar diameter measurements, highlighting the need to account for these effects in observational methods.

Findings

Image motion and stretching detected down to 0.001 Hz.

Low frequency seeing impacts drift-scan and heliometer measurements.

Atmospheric effects influence solar diameter accuracy.

Abstract

The action of the atmospheric seeing is blurring, image stretching and image motion. This happens even to the image of the Sun which is more than half degree wide. Low frequency seeing components affect the solar diameter values measured either throught the drift-scan or the heliometer methods. We present evidences of image motion and stretching down to 0.001 Hz.