The astronomical seeing at Kavalur.

Abstract

A summary of observing conditions at Kavalur Observatory is p0resented. These related to spectroscopic and photometric observations and to seeing as evaluated at the 102cm telescope. Nearly fifty percent of nights on which observations can be made have seeing better than 1.5arc seconds. Best observing conditions are in the months December to April when a high percentage of the nights are also photometric. There is some correlation of seeing with humidity; very good seeing is usually followed by a very low ground fog that fills in the valleys and ravines around Kavalur and seldom reaches he telescope that is located 20 meters above ground. Three component layers apparently contribute to seeing effects in the tropics. These are: (1) Thermal effects in the immediate vicinity of the telescope, (2) a layer, two to three hundred meters high which is the principal contributor and is dependent, (3) a high level contribution which is part of the large-scale global circulation.