Studio photographers may be familiar with the 1,000-watt quartz halogen lamps known as “FELs.” Scientists use them, too—specially calibrated ones, at least—to test the performance of light sensors that monitor Earth’s weather, plant life, and oceans, often from space.

A researcher at the National Institute of Standards and Technology (NIST) has recently made an improved mathematical model of the light output of FEL lamps. The new model, developed by NIST theorist Eric Shirley, will make the lamps more useful research tools, the scientists say, particularly for calibrating a relatively new class of cameras called hyperspectral imagers.

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