Light pollution at high zenith angles, as measured at Cerro Tololo Inter-American Observatory

TL;DR

This study measures V-band sky brightness at Cerro Tololo, confirming Garstang's model and revealing a twofold increase at high zenith angles under specific conditions, with no similar effect in the B-band.

Contribution

It provides empirical validation of Garstang's sky brightness model at high zenith angles and identifies conditions causing significant deviations.

Findings

V-band sky brightness matches Garstang's model at high zenith angles.

Enhancement factor of two observed without marine cloud layer.

No enhancement observed in the B-band under the same conditions.

Abstract

On the basis of measurements of the V-band sky brightness obtained at Cerro Tololo Inter-American Observatory in December 2006 and December 2008 we confirm the functional form of the basic model of Garstang (1989, 1991). At high zenith angles we measure an enhancement of a factor of two over Garstang's later model when there is no marine cloud layer over La Serena/Coquimbo. No corresponding enhancement is found in the B-band.