Structure of Non-thermal Radio Source G 55.7+3.4 in the Direction of CP1919

Abstract

Caswell and Goss¹ have reported the detection of an extended radio source G55.7+3.4 at 2,700 and 178 MHz in the direction of the pulsar CP 1919, and because of its non-thermal spectrum they have proposed that it might be a galactic supernova remnant (SNR) associated with the pulsar. They pointed out, however, that the age (5 × 10⁴ yr) and distance (7.5 kpc) of the assumed supernova remnant G55.7+3.4, calculated from its observed parameters, did not agree with those (age 10⁷ yr and distance 300 to 1,800 pc) of the pulsar CP 1919 calculated from the observed period, its rate of slowing down, 21 cm absorption studies and dispersion measure. But¹ these estimates are crude and consequently the apparent association should not be discarded as a chance coincidence. To investigate this apparent association further, we have mapped the region G55.7+ 3.4 at 11 and 21 cm wavelengths, with the 300 foot resurfaced telescope of the National Radio Astronomy Observatory.