The magnitude of a star measured at infrared wavelengths through an I filter. The wavelength of the I filter can have three separate values, depending on the system used. The wavelength and bandwidth on the Kron–Cousins RI photometry system are 798 and 154 nm; on the Johnson photometry system, 878 and 218 nm; and on the six-colour system, 1027 and 192 nm. The first is now the most widely used, and is sometimes denoted by the subscript KC or C.