JHK' imaging photometry of Seyfert 1. I.

This sample was selected to cover a range of radio emission strength, redshift from z=0 to 1, and absolute B magnitude from M_B_=-29mag to -18mag. Among low-z AGNs with z<0.3, Seyfert 1-1.5 AGNs are distributed over a region from a location typical of "galaxies" to a location typical of "QSOs" in the two-color J-H to H-K' diagram, but Seyfert 1.8-2 AGNs are distributed around the location of "galaxies".

Moreover, bright AGNs with respect to absolute B magnitude are distributed near the location of "QSOs," while faint AGNs are near the location of "galaxies". The distribution of such low-z AGNs in this diagram was found to have little dependence on their 6 cm radio flux. The near-infrared colors of the AGNs observed with an aperture of 7 pixels (7.49") are more QSO-like than those observed with larger apertures up to 15 pixels (16.1").