discovered by numerical modeling, the results are presented in Chapter 3.

During signal spectrum analysis we ignore a noise spectrum components correlation and use the spectrum shape only. Further modeling shows the same results if we use a pure white noise.

Selection of the Galactic Radiation Model
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Our approach is based on the spatial data filtering which reduces the influence of the Galactic spectrum index uncertainty. The accepted Galactic radiation model for the analyzed frequency region is assumed to involve a synchrotron component with frequency dependence as $T=T_0\nu^{\alpha}$, $\alpha=-3\pm 0.2$ and a bremsstrahlung component with spectral index $\alpha=-2.1$ (Bennett et al., 1992). If there are the space regions of a different nature of radiation on the line of sight, it may cause a spatial variation of the spectral index $\alpha$. Let us try to estimate roughly the contribution of such variation if we use some effective but constant value $\alpha_0$. Let the true value of the spectral index be $\alpha=\alpha_0+\Delta
\alpha$. After the frequency depended part is excluded from the data $T_1$ и $T_2$ of two frequency channels, one may derive: $$\delta T = T_1 \left(\frac{\nu_2}{\nu_1}\right)^{\alpha_0+\Delta
\alpha} - T_1
\left(\frac{\nu_2}{\nu_1}\right)^{\alpha_0} \approx
T_2 \left[ \left(\frac{\nu_2}{\nu_1}\right)^{\Delta \alpha}
-1 \right] \approx
T_2 