Table 1 lists the coordinates, magnitudes and preliminary redshifts of all objects listed in the Hewitt & Burbidge (1993) catalog and located within a circle of radius centered on Q0122-380. These 11 objects along with Q0122-380 itself were observed with the ESO 3.6 m telescope and ESO Faint Object Camera and Spectrograph (EFOSC1) on 1995 September 28. EFOSC1 was equipped with a thinned back-side illuminated TEK CCD with 512512, 27 µm pixels. We used a 230 Å mm-1 (B300) grism in combination with a 2" wide slit to obtain spectra covering the wavelength range 3750-6950 Å at 20 Å (FWHM) resolution. The spatial resolution is 0.61" pixel-1.
Table 1. Objects observed in the field of Q0122-380.
The seeing conditions on both nights were poor. Nevertheless, the high throughput of EFOSC1 ensured good signal-to-noise (S/N) spectra of objects as faint as (S/N8 in the continuum near 5500 Å). For most objects we took a single 1200 s exposure. For 0117-379, being the faintest target at , we exposed for 1800 s. Prior to each spectroscopic observation, EFOSC1 was used in direct (filterless) imaging mode for target verification and automated slit acquisition. One quasar candidate, 0117-378, was not found at or near its catalog coordinates.
The data were reduced within the IRAF environment, following standard techniques. The spectra were put on a relative flux scale based on the standard stars LDS 235/EG 63 and LTT 2415 (Baldwin & Stone 1984; Stone & Baldwin 1983). The absolute calibration is ill determined, due to variations in seeing and atmospheric extinction over the night.
The resulting spectra of the 8 confirmed quasars are shown in Fig. 1 along with the relevant emission line identifications. The measured redshifts given in Table 1 were determined by averaging the redshifts measured for individual emission lines (e.g. Ly, N V 1240, C II 1335, Si IV /O IV ] 1400, C IV 1549, He II 1640, Al III 1857, C III ] 1909, and Mg II 2799). For the wavelength of an emission line we adopted the average of the wavelengths of the peak (maximum signal) and of the center of a gaussian fit to the line, both determined after subtraction of the quasar continuum.
Two of the quasar candidates, 0121-379 and 0123-372, turn out to be Galactic stars. Their spectra are shown in Fig. 2. Unfortunately, of the observed quasar candidates 0121-379 would have been the quasar closest to Q0122-380, at an angular separation of .
© European Southern Observatory (ESO) 2000
Online publication: July 7, 2000