Characterizing the diffuse foreground for redshifted 21-cm HI signal: GMRT 153 MHz observation

Detailed knowledge of the foreground structure on the angular scales of ∼ 1° to sub-arcminute will be essential for extracting the redshifted 21-cm HI signal from the observed data. We have presented results from the GMRT observations at 153 MHz, which was used to characterize the statistical properties of the diffuse radiation, using the multi-frequency angular power spectrum, across sub-degree angular scales. We have detected fluctuations in the diffuse emission on angular scales greater than 10' in a low galactic latitude area. The total intensity angular spectrum shows a power-law behaviour, while the detection of diffuse emission at smaller angular scales is limited by residual point sources. Also, we have estimated the level of foreground contamination