Abstract
WE report here the discovery of an X-ray emitting QSO, the first to be initially identified from X-ray observations. Previously, the only QSO known to be an X-ray source was 3C273 (refs 1 and 2). The new QSO has been found within a 40′′ error circle established by the SAS-3 X-ray Observatory. The SAS-3 error circle lies within the Ariel V error box (∼0.2 square degrees) for the source 2A 2251-179 (ref. 3). Following the convention for optical QSOs, we have designated the optical object MR2251 — 178. The X-ray luminosity (2–11 keV) of this object, presently ∼5×1044 erg s−1, has been as large as ∼1.6×l045 erg s−1 (in 1975) and exceeds the optical luminosity by a factor of ∼ 10. Among known compact X-ray sources, only 3C273 has a greater luminosity. Also, in radio observations at 4,885 MHz with the NRAO Very Large Array (VLA), we have discovered a point-like radio source coincident with MR2251—178.
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RICKER, G., CLARKE, G., DOXSEY, R. et al. Discovery of an X-ray QSO. Nature 271, 35–37 (1978). https://doi.org/10.1038/271035a0
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DOI: https://doi.org/10.1038/271035a0
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