VizieR Online Data Catalog: Swift X-ray obs. of 31 SMS4 QSOs & radio gal. (Maselli+, 2022)

The SMS4 sample comes from a compilation of the Molonglo Southern 4Jy (MS4) sample which included 228 sources that were all imaged at 843MHz with the Molonglo Observatory Synthesis Telescope (MOST) to establish accurate positions, flux densities, and angular sizes. 133 MS4 sources with largest angular size (LAS) <35" were also selected for high-resolution imaging at 5GHz with the Australia Telescope Compact Array (ATCA). Optical identification for all MS4 sources was pursued complementing the analysis on plates from the UK Schmidt Southern Sky Survey with R-band CCD images made with the Anglo-Australian Telescope (AAT). Furthermore, spectral information at other frequencies was collected from the literature to derive S₁₇₈ for all MS4 sources. Hence, by using the same flux density threshold S₁₇₈^* as in the 3CRR catalog (Laing+ 1983, J/MNRAS/204/151), a strong-source subset of 137 sources with S₁₇₈>=S₁₇₈^*, called SMS4, was created.

In this paper, we report on a Swift observing program of the SMS4 sample, including 31 sources with no X-ray observations in the Chandra or XMM-Newton archives. A total of 24 sources were observed for the first time as a result of a dedicated proposal, while six were already present in the Swift archive when our dedicated campaign started, in 2015 November. The remaining source, PKS B2148-555, was observed in 2019 February.

The Swift observations of the ensemble discussed here include 24 sources observed (mainly between 2015 November and 2016 September) as part of an initial Swift proposal. Among these, five sources were observed again between 2019 and 2021 by chance (MRC B1017-421 and MRC B1036-697) or from subsequent Swift Target of Opportunities (ToO) requests (MRC B0547-408, MRC B0906-682, and MRC1451-364). In 2021 October, the 24 sources were then supplemented with archival observations for seven additional sources: MRC B0157-311, MRC B0407-658, MRC B0743-673, MRC B0842-754, MRC B1413-364, MRC B1737-609, and PKSB2148-555. The full observational details are given in Table 2 (for detections) and Table 3 (for upper limits).

(5 data files).