A method for the compensation of a variable light source in photoelectric spectrophotometry is presented. The outputs of a scanning photo-cell and a monitoring cell are fed to two amplifiers. The outputs of these amplifiers are then fed to a self-balancing recording potentiometer. The equipment has laboratory as well as astrophysical applications. The limiting magnitude at which useful spectrophotometry with a resolution of 1<i>A</i> is approximately 4. Further development work is in progress.
W. A. HILTNER and A. D. CODE, "The Compensation for Seeing in Stellar Photoelectric Spectrophotometry," J. Opt. Soc. Am. 40, 149-152 (1950)