ClearDarkSky brings you:

Clear Sky Charts

Based on a numerical weather model, Clear Sky Charts are perhaps the most accurate and the most usable forecasters of astronomical observing conditions for over 6300 observatories and observing sites in North America.

Light Pollution Map

A color-coded map of the world showing sources and levels of light pollution (man-made light that lights up the night sky and reduces what astronomers can see). It is a mirror of David Lorenz's Light Pollution Atlas 2020, but superimposed on Open Street Maps. Used by many to find good observing sites. Used with permission

Limiting Magnitude Calculator

Computes the zenith brightness of the sky based on the altitude of the sun, altitude and phase of the moon, distance to the moon, solar cycle and a scattering model of the atmosphere. Computes the faintest star visible to the eye. Written by Ben Sugerman. Preserved here with his permission.

Offline Archive of Astronomy Forecasts

An offline archive of cloud-cover, transparency and seeing forecast maps from 2005 November to present. Machine readable extracts, in csv format, are available for a small fee. Data is available for any latitude/longitude withing the coverage area, not just existing clear sky charts.

Sample csv files: Cloud Cover Transparency Seeing

The web pages, computer programs and databases at are written by:

Attilla Danko
Software Architect | Software Designer
High Availability | Embedded Operating Systems | Large Systems

Too serious? Try my personal page and site map.

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Copyright 2023 Attilla Danko. Page updated 2023-05-28 01:54:37UT on server3..