Night Sky Brightness at Cerro Pachon

Measurements at Cerro Tololo

Cerro Tololo is closer to La Serena-Coquimbo and Vicuna than Cerro Pachon and is roughly estimated to suffer 65% more light contamination than Cerro Pachon.

We have, near sunspot minimum 1987-1988, from measurements by A. Walker

U = 22.0 mag/arcsec2
B = 22.7
V = 21.8
R = 20.9
I = 19.9

And compare these to measurements by M. Phillips in 1997

B = 22.8
V = 22.2

and at ZD=45 deg in the direction of La Serena+Coquimbo

B = 22.6
V = 21.8

Given that the likely error on each measurement is approximately +/-0.15 mag (see discussion in Krisciunas 1997) we conclude that there is NO increase in light pollution detectable in broad-band colors. We will continue to monitor through the next solar cycle.