Attempt to measure the metallicity of galaxies far into their halos

Attempts were made to extend photoelectric CN measures to large radial distances in three galaxies. Low surface brightnesses preclude very definite conclusions, but the E0 galaxy NGC 1399 appears to be metal-rich out to 20 kpc from its center, while the S0 galaxy NGC 1553 and the Sa galaxy NGC 7814 show a definite CN decrease to a likely extreme Population II level. Measurements of the CN strength were also made for several southern halo globular clusters of our Galaxy