to near the Earth’s orbit and have a temperature of around 150–300 K. MMR dust, at $\sim 1$ au, has a temperature of around 280 K. Such dust exhibits a spectral peak at $\lambda < 50~\micron$ [@Spiesman95; @Reach97]. The ZE contribution to the WIDE-L (140 $\micron$) map is much smaller than that to the WIDE-S (90 $\micron$) map. To reduce the contribution from Galactic dust and extract the small-scale ZE structures, we subtracted 0.30 times the WIDE-L intensity ($0.30 \times I_\mathrm{WIDE-L}$) from the WIDE-S intensity ($I_\mathrm{WIDE-S}$) for both the leading and trailing maps. We derived the factor of 0.30 as follows: $$\frac{\int_\mathrm{WIDE-S} B_\nu(18.5~\mathrm{K})~(\nu/\nu_{0})^{2}~R_\mathrm{WIDE-S}(\nu)~ \mathrm{d}\nu
/ \int_\mathrm{WIDE-S} R_\mathrm{WIDE-S}(\nu)~ \mathrm{d}\nu}
{\int_\mathrm{WIDE-L} B_\nu(18.5~\mathrm{K})~(\nu/\nu_{0})^{2}~R_\mathrm{WIDE-L}(\nu)~ \mathrm{d}\nu
/ \int_\mathrm{WIDE-L} R_\mathrm{WIDE-L}(\nu)~ \mathrm{d}\nu} \sim 0.30,$$ where $B_\nu(18.5~\mathrm{K})$ is the Planck function at a temperature $T = 18.5$ K, $R_\mathrm{WIDE-S}(\nu)$ and $R_\mathrm{WIDE-L}(\nu)$ are the relative spectral responses of the WIDE-S and WIDE-L bands, respectively [@Doi15], and $\nu_{0}=3000$ GHz is the reference frequency corresponding to $\lambda \simeq 100~\micron$. Based on previous studies (e.g., [@SFD98; @Planck14-11]), we assumed that the temperature of the interstellar dust is $T \sim 18.5$ K and the emissivity of the interstellar dust has a frequency (wavelength) dependence $(\nu/\nu_{0})^{2}$ at wavelengths longwards of 100 $\micron$. In these 