"How do we measure sky brightness?" is a question we frequently hear at IDA. With the rapidly growing awareness of light pollution, there is an increasing interest in how to measure sky brightness and light pollution. Educators, National Park Service (NPS) personnel, environmentalists, biologists, and astronomers, both professional and amateur, need such measurements; however, the precise methods traditionally used by professional and amateur astronomers are beyond the needs, resources, and capabilities of many groups. 

On January 29, IDA hosted a workshop on sky brightness measurement techniques. Organized by Don Davis and Roy Tucker, the workshop addressed how to build an inexpensive (< US$1,000), easy-to-use system for non-technically trained personnel to measure sky brightness to a precision of 10% or better. 

Methods discussed ranged from star counts to aperture photometry to CCD photometry. Particularly intriguing was a simple photometer designed by Art Upgren and a simple visual photometer designed by Roy Tucker. The 21 participants included formal and informal educators, NPS personnel, professional and amateur astronomers, engineers, and IDA personnel. (See photo below.)

Our workshop was composed of some sub-groups. Chad Moore reported that the CCD group recommended a quarter-sky CCD camera to be used in sky brightness measurements. Chad subsequently contacted SBIG Instruments, and an engineer there agreed to help with a solution. He is working with different CCD camera configurations to meet our needs. One hurdle is that most wide field lenses require a short distance from lens to detector plane. One reason he agreed to help us is that there is parallel interest from meteor observers who want to capture a large swath of the sky with a CCD, but there is no known off-the-shelf solution. 

Workshop proceedings will be compiled and should provide sufficient information to enable one to measure the sky brightness at differing levels of accuracy. This workshop was the first in a series that will focus on issues in light pollution. If you are interested in organizing such a workshop, please contact IDA Headquarters.
 

                                                                                      Don Davis 
                                                                         President, Board of Directors 
                                                                     International Dark-Sky Association