LA Palma Night-Sky Brightness

TL;DR

This study measures the night-sky brightness above La Palma over several years, analyzing factors like airglow, zodiacal light, and light pollution, and compares it to other dark sites.

Contribution

It provides a comprehensive dataset of sky brightness measurements at La Palma, highlighting the effects of solar activity, ecliptic latitude, and airmass on sky brightness.

Findings

Sky brightness similar to other dark sites at sunspot minimum

Airglow and zodiacal light are main contributors to sky brightness

Light pollution contribution is minimal at zenith

Abstract

The brightness of the moonless night sky above La Palma was measured on 427 CCD images taken with the Isaac Newton and Jacobus Kapteyn Telescopes on 63 nights during 1987 - 1996. The median sky brightness at high elevation, high galactic latitude and high ecliptic latitude, at sunspot minimum, is B = 22.7, V = 21.9, R = 21.0, similar to that at other dark sites. The main contributions to sky brightness are airglow and zodiacal light. The sky is brighter at low ecliptic latitude (by 0.4 mag); at solar maximum (by 0.4 mag); and at high airmass (0.25 mag brighter at airmass 1.5). Light pollution (line + continuum) contributes < 0.03 mag in U, approximately 0.02 mag in B, approximately 0.10 mag in V, approximately and 0.10 mag in R at the zenith. This paper is a summary of results which are presented in full elsewhere (Benn & Ellison 1998, La Palma Technical Note 115).