The estimated brightness of the Cygnus loop supernova remnant (SNR) at 2720,
1420, 820, 408 and 34.5 MHz are presented. The observations of the continuum
radio emission are used to calculate the mean brightness temperatures and
surface brightnesses of this loop at the five frequencies in wide spectral
range, using the method we have previously developed for large radio loops. The
spectrum for mean temperatures versus frequency between the five frequencies is
estimated and the spectral index of Cygnus loop is also obtained. Also, from
our results can be concluded that Cygnus loop evolves in the low density
environment and the initial energy of supernova explosion was relatively low.
The obtained results confirm non-thermal origin of the Cygnus radio loop and
show that our method is applicable to almost all remnants.Comment: 12 pages, 5 tables, 11 figures. Accepted for publication in RevMexA
