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Internal Refraction in Meridian Circles

Published online by Cambridge University Press:  04 August 2017

E. Høg
E. Høg*
Affiliation:
Copenhagen University Observatory

Abstract

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Tube refraction of the order 0″.3 inside a meridian circle is a source of systematic errors that has not been noticed before. Natural convection due to cooling at night or heating during day will create primarily vertical temperature gradients in the air. This is shown by experiments at a collimator where typically 1 K/m was found inside the tube even when the gradient outside the tube was much smaller. A method of tangential ventilation of the tube was used to eliminate the gradients. It is shown that the resulting effect on seeing or image motion will be to the better when the ventilation system is properly designed, and the design for a conventional meridian circle and for a Glass Meridian Circle is discussed.

Type
VI. Transit Circles and Astrolabes
Information
Symposium - International Astronomical Union , Volume 109: Astrometric Techniques , 1986 , pp. 533 - 542
Copyright
Copyright © Reidel 1986 

References

Helmer, L., 1986, this volume.Google Scholar
Ningsheng, Hu, 1986, this volume.Google Scholar
Høg, E., 1973, Mitt. der Astron. Ges. Nr. 32, pp.120 Google Scholar
Høg, E., 1978, IAU Colloquium No. 48, Vienna, pp.229 Google Scholar
Høg, E., 1986, The Glass Meridian Circle, this volume (Paper I) Google Scholar
Kirijan, T.R., Pinigin, G.I., Timashkova, G.M., 1982, Izvestija Glavnoj Astronomicheskoj Observatorii b Pulkove (in Russian), No. 199, pp.43 Google Scholar
Miyamoto, M. and Yoshizawa, M., 1986, A New Method for Zenith Distance Determination, this volume.Google Scholar