<title>Mirror seeing control in thick solid mirrors and the planned upgrade of the McMath-Pierce Solar Telescope</title>

Abstract

It is well known that telescope mirrors can produce seeing effects when they are at a different temperature than the adjacent air. The mirror acts as a reservoir for heat that can be convected to/from the air. In this paper we will discuss some tactics for minimizing mirror seeing in nighttime and daytime (solar) telescopes. Aluminum mirrors with internal fluid cooling appear to be the optimum choice for mirror substrates as a means for reducing mirror seeing. However, the mirrors must be actively corrected for the distortions caused by thermal gradients. The planned provisions are described.