Radio SED for the identified apertures (E1–E4) shown in Figs. 2 and 3. (a) SED determined using the maps at 150, 402, 735, 887, 943, 1425, 4860, and 8689 MHz. The data point at 402 MHz (Band 3) is a lower limit (see Sect. 3.1 for details). (b) SED determined using the maps of the six sub-bands (622, 657, 692, 728, 761, and 801 MHz) of the Band 4 GWB uGMRT data. The uncertainty in the flux density measurements was estimated using (Lal 2021) ΔS = [(S_ν × f)² + rms² × N_beams]^0.5, where S_ν is the flux density, f is an absolute flux density calibration uncertainty (taken as 10%), and N_beams is the number of synthesized beams in the aperture.