RCW103 [@oli89].

On the opposite side of the SE filament lies another long ($\sim 2.'5$) filament within the northwestern SNR shell (Fig. 4). This filament (-NW filament) is relatively faint and appears to be clumpy. It has little correlation with the radio emission. We note that -SE and NW filaments lie roughly symmetric with respect to the line of position angle $\approx 60^\circ$, which is close to the inclination of the central PWN of 11p2 in X-ray [@rob03]. In addition to these two extended filaments, some faint, knotty emission features are also seen in the interior of the remnant, particularly in the southern area (Fig. 5). These features spread over an area of $\sim 2'$ extent and filametary, with some of them having a partial ring-like structure. There are also several bright clumps of $\sim 5''$ size. Most of the clumps appear to be connected to the filaments, although some are rather isolated. The brightnesses of these central emission features and NW filament are $\simlt 3\times 10^{-4}$ ergs cm$^{-2}$ s$^{-1}$ sr$^{-1}$. The observed total 164 flux is estimated to be $1.1\pm 0.2 \times 10^{-11}$ erg cm$^{-2}$ s$^{-1}$, $76\pm 12$% of which is from the SE filament.

### Spectroscopy

We have 