Bortle scale

Alex Pratt

Hi Paul, My interest was to see the range of sky conditions affecting the members, so a simple ‘Bortle 4’ tag suffices for me. Not everyone will have (access to) a SQM, so they can assess their site by using online references to the Bortle Scale and either use the partly subjective descriptions, e.g. “Bortle 4- NELM 6.1-6.5 and M33 is a difficult averted vision object, only visible when high in the sky” criteria or via their SQM reading, as you say. Clear – and dark – skies, Alex.