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We present a multi-frequency study of PKS J1222$+$0413 (4C$+$04.42), currently the highest redshift $gamma$-ray emitting narrow-line Seyfert 1 ($gamma$-NLS1). We assemble a broad spectral energy distribution (SED) including previously unpublished datasets: X-ray data obtained with the NuSTAR and Neil Gehrels Swift observatories; near-infrared, optical and UV spectroscopy obtained with VLT X-shooter; and multiband radio data from the Effelsberg telescope. These new observations are supplemented by archival data from the literature. We apply physical models to the broadband SED, parameterising the accretion flow and jet emission to investigate the disc-jet connection. PKS J1222$+$0413 has a much greater black hole mass than most other NLS1s, $M_mathrm{BH}approx2times10^{8}$ M$_odot$, similar to those found in flat spectrum radio quasars (FSRQs). Therefore this source provides insight into how the jets of $gamma$-NLS1s relate to those of FSRQs.
The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of gamma-ray emitting active galactic nuclei with low black hole masses. Like flat spectrum r
The detection of gamma-ray emission from narrow-line Seyfert 1 galaxies (NLSy1) has challenged the idea that large black hole (BH) masses ($ge$10$^8$ M$_{odot}$) are needed to launch relativistic jets. We present near-infrared imaging data of the gam
The discovery of $gamma$-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1) galaxies has questioned the need for large black hole masses (> 10$^8$ M$_{odot}$) to launch relativistic jets. We present near-infrared data of the $gamma$-ray-emitt
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 v
The narrow-line Seyfert 1 (NLS1) galaxy PMN J0948+0022 is an archetype of gamma-ray-emitting NLS1s in active galactic nuclei (AGNs). In this study, we investigate its radio structures using archival data obtained using the Karl G.~Jansky very large a