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DOI	10.1051/0004-6361/202038853
	Bolometric night sky temperature and subcooling of telescope structures
	Holzloehner, R.; Kimeswenger, S.; Kausch, W.; Noll, S.
通讯作者	Holzlohner, R (corresponding author), European Southern Observ ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany.
来源期刊	ASTRONOMY & ASTROPHYSICS
ISSN	0004-6361
EISSN	1432-0746
出版年	2021
卷号	645
英文摘要	Context. The term sky temperature is used in the literature to refer to different phenomena in different contexts which often leads to confusion. In this work, we study T-sky, the effective bolometric sky temperature at which a hemispherical black body would radiate the same power onto a flat horizontal structure on the ground as the night sky, integrated over the entire thermal wavelength range of 1-100 mu m. We then analyze the thermal physics of radiative cooling with special focus on telescopes and discuss mitigation strategies.Aims. The quantity T-sky is useful to quantify the subcooling in telescopes which can deteriorate the image quality by introducing an optical path difference (OPD) and induce thermal stress and mechanical deflections on structures.Methods. We employ the Cerro Paranal Sky Model of the European Southern Observatory to derive a simple formula of T-sky as a function of atmospheric parameters. The structural subcooling and the induced OPD are then expressed as a function of surface emissivity, sky view factor, local air speed, and structure dimensions.Results. At Cerro Paranal (2600m) and Cerro Armazones (3060m) in the Atacama desert, T-sky towards the zenith mostly lies 25-50 Kelvin below the ambient temperature near the ground, depending to a great extent on the precipitable water vapor column in the atmosphere. The temperature difference can decrease by several Kelvin for higher zenith distances. The subcooling OPD scales linearly to quadratically with the telescope diameter and is inversely proportional to the local air speed near the telescope structure.
英文关键词	telescopes instrumentation: miscellaneous atmospheric effects site testing radiative transfer convection
类型	Article
语种	英语
开放获取类型	Green Submitted, Bronze
收录类别	SCI-E
WOS记录号	WOS:000603048300001
WOS类目	Astronomy & Astrophysics
WOS研究方向	Astronomy & Astrophysics
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/347733
作者单位	[Holzloehner, R.] European Southern Observ ESO, Karl Schwarzschild Str 2, D-85748 Garching, Germany; [Kimeswenger, S.; Kausch, W.] Leopold Franzens Univ Innsbruck, Inst Astro & Teilchenphys, Tech Str 25, A-6020 Innsbruck, Austria; [Kimeswenger, S.] Univ Catolica Norte, Inst Astron, Av Angamos 0610, Antofagasta, Chile; [Noll, S.] Univ Augsburg, Inst Phys, Univ Str 1, D-86159 Augsburg, Germany; [Noll, S.] Deutsch Zentrum Luft & Raumfahrt DLR, Deutsch Fernerkundungsdatenzentrum, Munchener Str 20, D-82234 Wessling Oberpfaffenhofe, Germany
推荐引用方式 GB/T 7714	Holzloehner, R.,Kimeswenger, S.,Kausch, W.,et al. Bolometric night sky temperature and subcooling of telescope structures[J],2021,645.
APA	Holzloehner, R.,Kimeswenger, S.,Kausch, W.,&Noll, S..(2021).Bolometric night sky temperature and subcooling of telescope structures.ASTRONOMY & ASTROPHYSICS,645.
MLA	Holzloehner, R.,et al."Bolometric night sky temperature and subcooling of telescope structures".ASTRONOMY & ASTROPHYSICS 645(2021).