4 Follow-up spectroscopy

Candidates were verified by slit spectroscopy mainly with the 2.2 m telescope on Calar Alto, Spain, equipped with a Cassegrain Boller & Chivens spectrograph or since 1995 with the faint object spectrograph CAFOS. Some candidates were observed in August 1992 by N. Bade with ESO's EFOSC1 at the 3.6 m telescope on La Silla, Chile. HS0025+3047 was observed for a second time by W. Kollatschny from the Universitätssternwarte Göttingen with the 3.5 m telescope on Calar Alto equipped with the TWIN spectrograph because the resolution of our data had been too small to detect its narrow emission lines. Three further objects were observed as backup programme with the same telescope but equipped with the Focal Reducer in March 1996.

HS1216+5031 was serendipitously detected during the observations of the double quasar HS1216+5032 (Hagen et al. 1996). At a distance of $\approx 115 \hbox{$^{\prime\prime}$}$ this high redshift quasar is located on the opposite side of the brighter component at such a position angle that all three objects are visible in one slit position of the spectrograph.

Flatfield correction and wavelength and flux calibration of the CCD data followed standard procedures (cf. Stickel et al. 1993). In Table 1 the epoch, used instruments, and the achieved resolution are listed for all observing runs.

For all objects finding charts in postscript format and FITS files of the slit spectra are available on our Web page http://www.hs.uni-hamburg.de.

 

Table 1:   Epoch, spectrograph, and achieved spectral resolution of follow-up spectroscopic data. Except of run 1 at the 3.6 m-telescope of ESO and run 9 at the 3.5 m telescope on Calar Alto all data were obtained with the 2.2 m-telescope on Calar Alto

 

Table 2:   QSOs with detectable neighbours on direct Schmidt plates

For almost all objects with detectable neighbours on our direct Schmidt plates (distance 10$\hbox{$^{\prime\prime}$}$) the spectrograph was rotated to get both spectra simultaneously. Table 2 lists these objects with the object type of their neighbours. Already published are HS1216+5032 (Hagen et al. 1996) and HS1543+5921 (Reimers & Hagen 1998).

Table 3 (available at the CDS) lists for all objects the position for equinox 2000.0 with an accuracy , the B magnitude obtained from the Schmidt plates with an accuracy (see Paper I), the redshift, and the number of the campaign of Table 1 in which the data were obtained. Calibrated flux data of the objects are shown in Fig. 3 (available in the on-line version of this paper). Absolute flux calibration cannot be provided due to varying weather conditions during the various observing runs.