4 Results

After averaging we obtained spectra of very high signal-to-noise with enormous number of weak features, which rest wavelengths are estimated using the radial velocities of interstellar sodium lines. The present survey covers spectral range between 5650 and 6865 Å excluding the region of strong telluric O₂ contaminating lines from 6295 to 6350 Å and the region in the vicinity H$_{\alpha}$ line between 6563 and 6595 Å.

The decision that the feature is interstellar was made after the stellar line test and on the basis of the requirements that it is well seen in our averaged spectra and the spectrum of HD 210839 (the weak interstellar features are generally better seen in "zeta'' type spectrum than in "sigma'' type spectrum). Our survey does not contain broad DIBs; echelle spectra are not proper tools to search for such features. Thus the newly discovered DIBs are narrow. Such weak features must not be stellar (see the rotational velocities listed in Table 1).

In Table 2 we present all certain DIBs detected in averaged spectra of "sigma'' and "zeta'' clouds and marked with big asterisks in Fig. 4. The features published in other works are marked without any additional designation ( $\lambda5705.43$ for instance) just by segments of straight solid lines.

First column in Table 2 gives the wavelength of the feature measured in the averaged spectrum of "zeta'' or "sigma'' type (weak features are generally better seen in spectrum of "zeta'' cloud). Uncertainities of the wavelengths do not exceed $\pm$0.1 Å for the features not signed with a colon. Some of the features are extended and their tabulated wavelengths refer to the centre of line. In case of sharp and asymmetric features the measured wavelength originates from the deepest point in the line.

The second column contains equivalent widths (EW) in mÅ for the features measured in the spectrum of HD 210839. Some of the features were blended with stellar and telluric contaminants and they are signed with (bl) as the correct measurement of EW was not possible. In the noisiest regions of the spectra for the very weak features the error in EW can be as large as 50%. Uncertain entries are marked with a colon.

The third and fourth column describe the behaviour of DIBs in the averaged spectra of "sigma'' and "zeta'' type and the last column contains most important references for every feature.

The data in Table 3 apply to all uncertain features (those which were not clearly seen in all our spectra) and marked with small asterisks in Fig. 4. Most of them are very weak features, reported here for the first time.

 

 

Table 3: List of uncertain DIB's. Codes as in Table 2

$\lambda_{{\rm lab}}$	EW $\star$	In $\sigma$ cl.	In $\zeta$ cl.	references
Å	mÅ
5657.91		d	d	new
5660.98		d	d	new
5749.06		e	e	new
5800.74		f	e	new
5820.24	1.1:	e	e	new
5919.32	1.7:	e	d	new
5991.63	1.0:	f	e	new
5993.33	1.2:	f	e	new
6000.78		f	d	new
6056.38		e	e	new
6078.18		e	f	new
6111.36		e	e	new
6206.84		f	e	new
6209.90		e	f	new
6218.48	1.2:	e	d	new
...
6368.72	5.6	e	f	new
6377.09	bl	e	e	new
6433.71	2.0	e	d	new
6436.83	4.9	f	e	new
6468.53	bl	e	f	new
6496.67	0.6:	e	d	new
...
6691.65	2.5	e	f	new
6744.06	0.5:	e	e	new
6747.80	2.3	e	e	new
6812.80	7.2	e	d	new
6849.66		d	e	new
6855.54	3.7	e	e	new