Abstract
BL LAC (VRO 42.22.01) is the most rapid radio variable known1 and is also an optically violent variable2. It had long been thought to be a variable star3 and its low galactic latitude (l = 10°) suggests a possible galactic origin. These two facts have prompted two recent searches for similar objects. MacDonell and Bridle4 have investigated the spectra of known radio sources between l = ± 10°, and although they found three which had opaque microwave spectra (DW 0224+67, DA 93 and DW 0727 – 11), none of these was found to vary. They concluded that the sources were probably compact extragalactic objects. Recently, Biraud5 has compared the positions of variable stars with those of known radio sources and found two new coincidences. One of these, PKS 1514 – 24, was identified with AP Lib, which showed rapid optical variability between 1936 and 1939.
Article PDF
References
Andrew, B. H., MacLeod, J. M., Locke, J. L., Medd, W. J., and Purton, C. R., Nature, 223, 598 (1969).
Cannon, R. D., Penston, M. V., and Brett, Rosemary, A., Mon. Not. Roy. Astron. Soc., 152, 79 (1971).
Schmitt, J. L., Nature, 218, 663 (1968).
MacDonell, D. G., and Bridle, A. H., Nature, 227, 582 (1970).
Biraud, F., Nature, 232, 178 (1971).
Shimmins, A. J., Clark, M. E., and Ekers, R. D., Austral. J. Phys., 19, 837 (1966).
Kellerman, K. I., and Pauliny-Toth, I. I. K., Ann. Rev. Astron. Astrophys., 6, 417 (1968).
Nicolson, G. D., IEEE Trans., MTT-18, 169 (1970).
Brandie, G. W., and Stull, M. A., Nature Physical Science, 231, 149 (1971).
Kellerman, K. I., Clarke, B. G., Jauncey, D. L., Cohen, M. H., Shaeffer, D. B., Moffet, A. T., and Gulkis, S., Astrophys. J., 161, 803 (1970).
Bolton, J. G., and Wall, J. V., Astrophys. Lett., 3, 177 (1969).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
NICOLSON, G. Radio Sources similar to BL Lac. Nature Physical Science 233, 155 (1971). https://doi.org/10.1038/physci233155a0
Received:
Issue Date:
DOI: https://doi.org/10.1038/physci233155a0
This article is cited by
-
The development of radio astronomy at Hartebeesthoek
Astrophysics and Space Science (1995)
-
Intensity Variations in a Complete Sample of Radio Sources at 2,300 MHz
Nature Physical Science (1973)
-
Diameter of PKS 1514-24 (AP Lib)
Nature Physical Science (1972)
-
Two Variable Radio Sources
Nature Physical Science (1971)