Light Pollution Research
Night Sky Brightness Meter (NSBM)
Read the Current Status of the NSBM Report on the IDA Reports & Studies Page >>
A good estimation of sky brightness and its variations throughout the night, the months, and even the years is essential knowledge, both for good observing and especially as a tool in efforts to minimize sky brightness through local action. Hence, a stable and accurate monitor can be a valuable and necessary tool. Dan McKenna (of Palomar Observatory), in partnership with IDA, has developed such a tool. This device is now undergoing its beta test in preparation for production. It is simple, accurate, well calibrated, and automatic, sending its data directly to IDA over the Internet via e-mail. Approximately 50 such monitors will be ready soon for deployment worldwide, including most major observatories.
IDA SKY BRIGHTNESS RESEARCH
The Glare Metrics Program is a joint effort between IDA and Ian Lewin, of Lighting Sciences, Inc. This program is designed to create a standard of accurately and uniformly measuring glare, primarily by looking at intensity, luminance, and luminance contrast. There are several different methods used to determine the level of glare output by a variety of light sources. The first is the calculation of the intensity of the light source. The second is measuring the luminance contrast between the light source and the background. And finally, a more subjective approach is to ask individuals to rate their personal discomfort level when viewing the light source. These three methods will combine to create a clear and uniform standard for measuring and quantifying glare.
A function of the Glare Metric Program is the desire to involve lay people in light source measurements. This effort will record multiple types of light sources in a variety of locations. One of the set backs in this effort is the prohibitive expense and logistics in providing volunteers with a luminance meter capable of measuring the light’s output. It is, therefore, necessary to develop another more accessible means of measurement. Therefore, an experiment is in process to determine if a digital camera can be used as an alternative to a luminance meter. Read the preliminary report.