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Multifrequency observations of OV236 (1921-293) reveal an unusual spectrum

Gear, Walter Kieran ORCID:, Robson, E. I., Ade, Peter A. R. ORCID:, Griffin, Matthew Joseph ORCID:, Smith, M. G. and Nolt, I. G. 1983. Multifrequency observations of OV236 (1921-293) reveal an unusual spectrum. Nature 303 (5912) , pp. 46-47. 10.1038/303046a0

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As part of a programme of multifrequency single epoch observations of BL Lac objects and flat-spectrum radio sources we have examined the radio source OV236 (1921–293) which has been classified both as a quasar and a BL Lac object. Its polarization and variability at 2.2 µm1 and generally featureless optical spectrum are consistent with it being a BL Lac object. Wills and Wills2 measured its optical polarization, variability and emission line spectrum and find it to have a redshift z = 0.352. It is an extremely variable radio source, during the outburst reported by Dent and Balonek3 it was the brightest 10-cm quasar in the sky. The outburst was first measured at 3.3 mm and was increasingly delayed at longer wavelengths; there was also evidence for correlated optical/radio variability during this outburst4. We have obtained J, H, K, 10, 20, 800 and 1,100 µm flux measurements of 1921–293 over a period of four days from the same telescope, enabling us to present a ‘snapshot’ of its IR to millimetre spectrum. The continuum spectrum of 1921–293 is suggestive of a peak in the submillimetre region. This excess could be due to an injection of high-energy electrons into a synchrotron emitting region, although thermal emission from dust remains a possibility.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
ISSN: 0028-0836
Last Modified: 17 Oct 2022 10:13

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