The ordinary life of the gamma-ray emitting narrow-line Seyfert 1 galaxy PKS 1502+036

We report on multifrequency observations of the gamma-ray emitting narrow-line Seyfert 1 galaxy PKS 1502+036 performed from radio to gamma-rays during 2008 August-2012 November by Fermi-LAT, Swift (XRT and UVOT), OVRO, VLBA, and VLA. No significant variability has been observed in gamma-rays, with 0.1-100 GeV flux that ranged between (3-7)x10^-8 ph/cm^2/s using 3-month time bins. The photon index of the LAT spectrum (Gamma=2.60+/-0.06) and the apparent isotropic gamma-ray luminosity, L(0.1-100 GeV)= 7.8x10^45 erg/s, over 51 months are typical of a flat spectrum radio quasar. The radio spectral variability and the one-sided structure, in addition to the observed gamma-ray luminosity, suggest a relativistic jet with a high Doppler factor. In contrast to SBS 0846+513, the VLBA at 15 GHz did not observe superluminal motion for PKS 1502+036. Despite having the optical characteristics typical of a narrow-line Seyfert 1 galaxy, radio and gamma-ray properties of PKS 1502+036 are found to be similar to those of a blazar at the low end of the black hole mass distribution for blazars. This is in agreement with what has been found in the case of the other gamma-ray emitting narrow-line Seyfert 1 SBS 0846+513.