follow-up spectroscopic observations of them using Long-slit Near-IR Spectrograph of the Palomar 5-m Hale Telescope [@lar96] in 2005 August. The spectrograph has a $256\times 256$ pixel HgCdTe NICMOS 3 array with a fixed slit of $38''$ length. We placed the slit along the bright and filaments crossing their peak positions. Toward the filament, four spectra around 1.25, 1.52, 1.63 $\mu$m (for emission), and 2.16 $\mu$m (for ) were obtained, while, toward the filament, one spectrum around 2.11 $\mu$m was obtained. Over the observations, the slit width was fixed to be $1''$, resulting in spectroscopic resolution of 650–850 with 0.06–0.12 $\mu$m usable wavelength coverage. For all the obtained spectra, the individual exposure time was 300 s with the same amount of exposure of nearby sky for sky background subtraction. For the lines, we performed the exposure twice (with different sky positions, but the same source position), and combined them, while, for the line, we performed the exposure only once.

Just after the source observations, we obtained the spectra of the G3V star HR 8545, which was at the similar airmass of the source by uniformly illuminating the slit using the f/70 chopping secondary of the telescope. We then divided the source 