In August 1991 and August 1994, 8 echelle observations of the quasar PKS 2126-158 were obtained at ESO (La Silla), with the NTT telescope and the EMMI instrument (see D'Odorico 1990). The ESO echelle #10 was used in the red arm of the instrument in combination with a grism cross-disperser. The seeing during the observations was typically between 0.8 and 1.3 arcsec.
The absolute flux calibration was carried out by observing the standard star EG274 (Stone & Baldwin 1983).
The data have been reduced in the context of the ECHELLE software package available in the 94NOV edition of MIDAS, the ESO data reduction system. Some improvements have been introduced with respect to the standard procedure. In particular, the spectra obtained from different observations are summed up without a previous rebinning but maintaining the original pixel sampling. For the wavelength calibration Thorium lamp spectra have been used. Wavelengths have then been corrected to vacuum heliocentric.
The weighted mean of the spectra is equivalent to
hours of
integration time and it presents a resolution 
.
The s/n ratio per resolution element at the continuum level is
doubled compared with the previous spectrum by
GCFT: it ranges from 
to 44 in the interval
4380-5190 Å, while beyond the Ly
emission it has a
roughly constant value of 
.
In addition to these data, 8 long slit observations of the spectrum of
PKS 2126-158 were obtained with an holographic grating (ESO #11) at the blue
arm of the EMMI instrument.
The reduction has been carried out with the LONG SLIT package of
MIDAS, using an optimal extraction option. The resolution of these
data is 
.
The resulting spectrum has been used to check the reliability of the Ly
identification process by verifying the presence of the higher order
Lyman series lines.
The journal of the observations is given in Table 1 (click here).
| date | exposure | slit | range | CCD |
| (yy mm dd) | (s) | width | (Å) | |
| 91 08 06 | 7200 |  | 4539-7055 | FORD 2k |
| 91 08 06 | 7200 | | 4539-7055 | FORD 2k |
| 91 08 07 | 9130 | | 4539-7055 | FORD 2k |
| 94 08 13 | 5380 |  | 4056-6635 | TK 2k #36 |
| 94 08 13 | 7200 | | 4056-6635 | TK 2k #36 |
| 94 08 13 | 7200 | | 4056-6635 | TK 2k #36 |
| 94 08 15 | 7200 |  | 4279-6644 | TK 2k #36 |
| 94 08 15 | 6645 | | 4279-6644 | TK 2k #36 |
| 94 08 14 | 2700 | | 3822-3980 | TK 1k #31 |
| 94 08 14 | 2700 | | 3822-3980 | TK 1k #31 |
| 94 08 14 | 2700 | | 3686-3846 | TK 1k #31 |
| 94 08 14 | 2700 | | 3686-3846 | TK 1k #31 |
| 94 08 15 | 3600 | 3825-3983 | TK 1k #31 | |
| 94 08 15 | 3600 | 3825-3983 | TK 1k #31 | |
| 94 08 15 | 3600 | 3687-3848 | TK 1k #31 | |
| 94 08 15 | 3000 | 3687-3848 | TK 1k #31 | |