On the influence of stray light on total ozone measurements made with Dobson spectrophotometer no. 118 in Athens, Greece

Dobson spectrophotometer measurements are known to be subject to stray ligh t errors. To study these errors with Dobson spectrophotometer no. 188 in At hens, Greece, a series of total ozone measurements were taken out to high a irmasses extending as far as mu= 3.0. The results were compared to the simp le monochromatic-heterochromatic stray light model introduced by Basher. Th ese comparisons showed that the instrument's R-o value was between 10(-3.5) and 10(-3.4). These R-o values indicate that the instrument does not intro duce any stray light interference for the regular observations performed at Athens. The value of the other parameter, a, of the Basher model varied be tween 0.6 and 0.9, having a weak dependence on the total ozone amount.