OzSSy1: The Australian Southern Seyfert-1 Spectroscopic Atlas and Catalogue at z < 0.1

Neelesh Amrutha, Christian Wolf, Christopher A. Onken, Wei Jeat Hon, Samuel Lai, Rachel Webster

First listed 2026-06-29 | Last updated 2026-06-26

Abstract

We present a spectroscopic atlas of 887 broad-line active galactic nuclei (AGNs) in the Southern sky, spanning redshifts $z < 0.1$, declinations $δ< 0$ deg and Galactic latitudes $|b| > 10$ deg. The sample aims at being a largely complete census of nearby broad-line AGN. The atlas is constructed from observations with $R\sim3000$ using the integral-field Wide Field Spectrograph at the Australian National University 2.3 m telescope. Spectra are extracted in a 6.7 arcsec aperture and have a median signal-to-noise ratio of 13 and 23 per Angstrom in the blue and red arms, respectively. Each spectrum is accompanied by a spectral decomposition that models the AGN continuum and host galaxy, along with fits to the emission lines H$γ$, H$β$, H$α$, He II, He I, [O III], [O I], [N II] and [S II], including broad Balmer and Helium components. The data products are publicly available and designed to support studies of population demographics and AGN variability in conjunction with future time-domain surveys.

Short digest

OzSSy1 delivers a publicly available spectroscopic atlas and catalogue of 887 southern broad-line AGN at z < 0.1, observed with the WiFeS integral-field spectrograph at R~3000 and extracted in a 6.7 arcsec aperture. The sample is built to be a largely complete nearby Seyfert-1 census, drawn mainly from the 6dFGS broad-line AGN population and supplemented with S7 Seyferts and bright point-source AGN missed by galaxy-based selection. Each object comes with AGN-host continuum decomposition and emission-line fits for the Balmer, helium, and standard narrow forbidden lines, making the release immediately useful for single-epoch line measurements, demographic work, and classification. Its main value is as a modern homogeneous southern reference set for long-baseline variability studies and future time-domain surveys, especially where older 6dFGS spectra were not ideal as flux-calibrated comparison epochs.

Key figures to inspect

• Figure 2. Use this as the sample-definition figure. It shows how the atlas populates magnitude, redshift, and AGN continuum-luminosity space, and it makes clear that the catalogue combines host-selected 6dFGS Seyferts with supplementary bright AGN to improve completeness at the luminous, point-source end.
• Figure 6. This is the clearest figure for what the data product actually contains. The decomposition examples demonstrate the separation of AGN continuum and host galaxy light, the fitted emission-line model, and the range of host contrast and Balmer-line quality that users should expect across the atlas.
• Figure 10. Include this to document how the catalogue’s type labels are assigned. The decision tree is central for any reader who wants to use the release for population work, because it turns the fitted spectral components and quality cuts into the final AGN classifications and identifies the spectra excluded as bad quality.
• Figure 9. This is a strong physics-diagnostic figure rather than a setup figure. The Balmer-line FWHM comparisons test the internal consistency of the broad-line fits across Hα, Hβ, and Hγ, showing that Hβ/Hα follows the reverberation-mapping-based expectation while Hγ/Hβ departs from it.
• Figure 15. This figure best captures why the atlas matters beyond cataloguing. The MCG 06 30 015 flare sequence shows how a homogeneous baseline spectrum plus repeat WiFeS observations can isolate transient spectral changes on week-scale follow-up, exactly the kind of use case the release is designed to enable for time-domain AGN science.