<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31443950</termId><termName>astronomical mirrors</termName><termType>PT</termType><termNote><![CDATA[ Mirrors used in the place of lenses in astronomical instruments; they may be large, they do not absorb radiation, and are often aspheric to reduce aberrations.  ]]></termNote><termCreatedDate>2026-03-30 20:52:51</termCreatedDate><relation><relationType>UF</relationType><termId>31443951</termId><termName>astronomical mirror</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31443952</termId><termName>mirrors, astronomical</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31383815</termId><termName>astronomical instruments</termName><termType>PT</termType></relation></term>  </Zthes>