harmonics expansion coefficients, $$\begin{aligned}
\langle a_{lm}a_{l'm'}^* \rangle = \delta_{ll'}\delta_{mm'} \langle C_l \rangle,\end{aligned}$$ where $\delta_{ii'}$ is Kronecker symbol and, $$\begin{aligned}
a_{lm}(\nu) = \int  d{\Omega} ~ Y_{lm}^* ~ I (\nu,{\bf{\theta}}).\end{aligned}$$ Here $ I (\nu,{\bf{\theta}})$ is intensity of the images.

To calculate the APS from images, we use Polspice[^2][@Chon2004], which is originally developed for estimating the CMB polarization power spectrum. The APS is evaluated via weighted correlation function of images, and full method is described in [@Chon2004]. The Polspice has been used in some literatures such as the BICEP 2yr data analysis [@2010ApJ...711.1123C], the CMBPol mission concept study [@2009AIPC.1141..222D] and the angular power spectra of the Planck frequency maps . Note that an image created from visibility has weight effect caused from the uv-coverage. For correct estimation of APS, we have to correct the weight. The correction method is described in the Appendix.

The units of the images made by using the RTS is Jy/beam, and we need to convert Jy/beam into K. However, the conversion is not straightforward because it needs an accurate beam model. Thus, in this work, we normalize the APS of the images using a constant factor so that the image APS is consistent with the APS calculated from 