boundary. Its peak surface brightness is $3.0\pm 0.3  \times 10^{-4}$ erg cm$^{-2}$ s$^{-1}$ sr$^{-1}$ and its flux is $4.3 \pm 0.4 \times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$. The NE filament (H$_2$-NE filament) is just outside of the SNR boundary and is located where the radio continuum boundary is distorted. Its surface brightness is $\simlt 40$% of the SE filament peak brightness, while its flux density is $\sim 50$% of the SE filament. There is no 164 emission associated with either filament. A long ($\sim 2'$) filamentary feature seems to be present well outside the southeastern SNR boundary, but it is too faint to be confirmed.

Fig. 9 shows a detailed structure of the -SE filament. It is composed of two bright segments surrounded by a diffuse envelope. It is just outside of the bright -SE filament, but there is no apparent correlation between the two (cf. Fig. 3). We have detected two lines, (1,0) S(1) and (2,1) S(3), toward the peak position of the filament, -pk1 (Fig. 10). Their dereddened ratio, using the column density derived from line ratios ($A_{2.12 \mu {\rm m}}=1.59$ mag), is $0.14\pm 0.01$ (Table 2), which gives $\tex\approx 2,100$ K using the transition probabilities of [@wol98].

Discussion
