BL Lac identified as a Radio Source [3]

Abstract

I WISH to draw attention to the fact that a new position (α1950 Combining double low line 22h 00m 38s.9 ± 0s.7, δ1950 Combining double low line +42°02′ 09″±9″) and optical identification1 of the radio source VRO 42.22.01 (ref. 2) determined with the Algonquin Radio Observatory 150 ft. telescope places it coincident with the irregular variable star BL Lac. BL Lac was discovered by Hoffmeister3, and varies from the thirteenth to sixteenth magnitude with fluctuations of large fractions of a magnitude in a few days4. A finding chart is published by Hoffmeister5; the position of the variable in the chart by Semakin4 seems to be slightly in error. Examination of a glass copy of the National Geographic Society and Palomar Observatory Sky Survey at the Dunlap Observatory shows marginal nebulosity about the star. The optical properties of this object combined with its radio polarization and unusual microwave spectrum1 make it outstandingly interesting. ö © 1968 Nature Publishing Group.