Photometry and Polarimetry

The most widely used photometric system, photographic B and V, has serious systematic problems that are not generally recognized. The photographic sensitivity bands do not match well with the corresponding photoelectric sensitivity bands; and as a result, the photographic systems each have a colour coefficient of the order of 0.1 (B–V) with respect to the photoelectric systems. These colour coefficients are serious, they are poorly known, and they are usually ignored.