Plots of Q2 and Q4f (Power Offset) showing the detection limit for Stokes-I (α = 10^−3.5) for thefrequency range 50–60 MHz. Panels a and b: Q2 before elliptical correction. Panels c and d: Q4f difference of the two beams before elliptical correction. Panels e and f: Q2 after elliptical correction. Panels g and h: Q4f difference of the two beams after elliptical correction. The comparison of the two OFF-beams from Obs #2 can be found in the left column (panels a, c, e, g) and the comparison of ON-beam (Jupiter) vs. OFF-beam 2 can be found in the right column (panels b, d, f, h). The dashed lines for panels c, d, g, and h are the 1, 2, 3 σ statistical limits derived from two different Gaussian distributions (each run 10 000 times). Panel h: excess of ON vs. OFF points at ≥2 σ statistical significance for signals up to a threshold of 4σ. For comparison, in panel g all the excess points are mostly below the 1σ statistical significance level. We find by performing Gaussian simulations that the probability to obtain a curve like panel g is ~99%, whereas the probability to reproduce a curve like panel h is ~10⁻⁴.