Left: Spectral index map between 144 and 400 MHz for SDSSTG8102. The overlaid black contours are from uGMRT 400 MHz, starting with 3σ_rms × [1, 2, 4,...], where σ_rms = 30.5 μJy beam⁻¹, and the blue circle indicates the BGG of the group. Middle: Spectral index map for SDSSTG16393. The contour level is similar to the upper panel, and σ_rms = 32 μJy beam⁻¹. Right: Same but for SDSSTG28674 with similar contour levels and with σ_rms = 28.7 μJy beam⁻¹.