Broad-band photometry of G and K stars - The C, M, T/1/, T/2/ photometric system

An alternative broad-band photometric system is described which is designed to obtain accurate photometric temperatures, metal abundances, and a cyanogen blanketing index for G and K giants. The filters defining the system are given along with the effective wavelength of each bandpass, the bandpass width for one-half maximum responsivity, and the response function of the system. A comparison with the UBV broad-band system shows that the C, M, T(1), T(2) system is more efficient since it requires less observing time to obtain all three parameters than the UBV system needs just for two of them. The reduction of observations is outlined, and the definition of the standard system is described in detail. Results are presented for abundance analyses of 36 G and K giants; 23 members of the Hyades, Praesepe, and M67; 7 super-metal-rich stars; and also 26 G-type dwarfs. Effects of reddening and luminosity on the metallicity and CN indices are examined.