2 New radial velocities

We have measured radial velocities of Galactic PNe in three separate observational programs. These concern 338 different PNe, 93 of which have for the first time a measured radial velocity. Some of these data have been published (Zijlstra et al. 1997); the remainder is presented here. The three programs are:

• 117 high-resolution data (ZASW, in part published in Zijlstra et al. 1997).
  In the context of a study of expansion velocities of galactic bulge PNe and of PNe with [WC]-type nuclei, accurate radial velocities were measured for a sample of 119 PNe (this sample we will designate ZASW). The observations were carried out with the ESO 1.4 m CAT telescope with the short camera (CES), and performed in 1993 June, in 1993 July and in 1994 March. Two spectral ranges were selected, one around the [OIII] 5007 line (R = 30 000, 1993 June), the other including H$\alpha$ and the [NII] red doublet (R = 60 000, 1993 July and 1994 March, see Acker 1993). Two PNe were discovered to belong to the Sagittarius Dwarf galaxy (Zijlstra & Walsh 1996), and therefore are excluded from our Galactic sample. The observations and the radial velocities of 71 bulge PNe (labelled as (z) in Table 2 (Col. 3) are presented in Zijlstra et al. 1997). The velocities of the 48 non-bulge PNe obtained from H$\alpha$ and [NII] (R = 60 000) measurements are given in Table 2 Col. 3 (labelled as (a)).
• 130 medium-resolution data (ASC).
  In the framework of chemical abundance determinations of galactic PNe high above the Galactic plane (Cuisinier et al. 1996), observations were conducted from 1993 to 1995 at the ESO 1.52 m telescope using the Boller & Chivens spectrograph and the 2048 $\times$ 2048 pixel FA27 CCD CCD. The wavelength range was 3600 - 7400 Å with a spectral resolution R $\simeq$ 1500. The entrance aperture was $1.5 \times 3.4$arcsec.
• 247 low-resolution data (SA).
  From 1983 to 1991, a spectrophotometric survey of galactic PNe was performed at the ESO 1.52 m telescope equipped with the Boller & Chivens spectrograph (see Acker et al. 1989b; Acker et al. 1992). Until 1987 the IDS detector was used, and afterwards a 512 $\times$ 1024 pixel CCD. The wavelength range was 3600 - 7400 Å with a spectral resolution R $\simeq$800. As the sample included a large number of Galactic bulge PNe, we measured the radial velocities of those 247 PNe despite the low resolution of the spectra.

The ASC and SA sample showed wavelength-dependent velocity residuals. To remove these, we applied a linear fit to these deviations per observing run (the slope of the fit changed between observing runs). The values on the blue part of the spectra appeared to be of poor quality (probably due to the low sensitivity of the detector) and were removed from the calculations. Each run was calibrated using the available ZASW values. Considering the mean dispersions of the spectra, measurements for which the uncertainties exceeded the expected ones were not included in the catalogue.

From the medium-resolution ASC data we obtained 130 radial velocities of sufficient quality, with a mean uncertainty of about 20 km$\,$s^-1. From the SA data we obtained 247 acceptable measurements with a mean uncertainty of about 40 km$\,$s^-1.

The galactic distribution of these 494 new data (including data published in Zijlstra et al. 1997) is displayed in Fig. 1.

  

Figure 1: Galactic positions of the new 494 radial velocities $\,-\,$top: 247 SA data; $\,-\,$middle: 130 ASC data; $\,-\,$bottom: 117 ZASW data