Limiting Magnitude Estimation

By Pierre Martin

Determining the exact sky darkness from your site is one of the things you have to do to make your meteor data useful to scientists. Sky darkness will vary depending on the amount of light pollution, among other factors. This may sound like an intimidating task to do, but it is really quite simple. All you have to do is find the locations of a few known stars. Then you count all the stars you can see (including corner stars) in a pre-determined triangle-shaped area in the sky. This will tell you your naked eye limiting magnitude. To find out more about those star triangles, please see the links below, to the International Meteor Organization. You can easily print the charts provided for use on the field.

Limiting magnitude estimation ( 30 triangle areas ) sky charts
http://www.imo.net/visual/major01.html#table2

Complete limiting magntitude conversion tables
http://www.imo.net/visual/lm.html