Red and Infra-Red Magnitudes and Colours for 300 F, G and K Type Stars

Red and infra-red magnitudes and colours for about 300 F, G and K type stars were measured at Kitt Peak National Observatory, Arizona. The photometer consisted of a 16 in. (40 cm) Cassegrain reflector, an RCA 7102 photo-multiplier and the following filters: a $$\bar \lambda$$ = 6900 Å interference filter ( r ), a Schott RG 8 optical glass, a Schott RG 9 and a $$\bar \lambda$$ = 1.00 μ interference filter ( i ). The natural r , ( r – rg 8) and ( r – rg 9) scales show good agreement with the R and ( R–I ) scales of Kron et al . for the F, G and K type stars but not for earlier types. The standard error for a single difference from Kron, excluding the early types, is 0 ^m .022 in r , 0 ^m .015 in ( r–rg 8) and 0 ^m .016 in ( r – rg 9). There is also good agreement between ( r – i ) and the ( R – I ) of Arizona–Tonantzintla after a linear transformation has been applied to ( r – i ). Again types earlier than F have to be excluded, and the standard error of a single difference then is 0 ^m .018.