BL Lac identified as a Radio Source

Abstract

I WISH to draw attention to the fact that a new position (α₁₉₅₀ = 22^h 00^m 38^s.9 ± 0^s.7, δ₁₉₅₀ = +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.