From top left a), top right b) to bottom left panel c): λ6 cm, λ11 cm, and the λ21 cm total intensity images of the Origem Loop. The angular resolutions are 95, 95, and 94, respectively. The contours run from 2ⁿ × 3.6 (3σ) mK  T_B, (n = 0, 1, 2 ...) for the λ6 cm image, 2ⁿ × 18.0 (3σ) mK  T_B, (n = 0, 1, 2 ...) for the λ11 cm image, and 2ⁿ × 66.0 (3σ) mK  T_B, (n = 0, 1, 2 ...) for the λ21 cm image. The white circle in the top left panel a) indicates the boundary of the Origem Loop. Bottom right panel d): spectral index distribution for the Origem Loop area derived from the Urumqi λ6 cm, Effelsberg λ11 cm, and λ21 cm images at the same angular resolution of 9 5.