Astron. Astrophys. 332, 721-731 (1998)

2. Observations

The nebulae were observed on March 1994, at the 1.52m ESO telescope of La Silla, Chile, equipped with a Boller & Chivens spectrograph. On three nights, spectra of the nebulae covering the range from 360 nm to 840 nm were obtained with the long slit of the spectrograph positioned along the major or minor axis of the nebulae. On a fourth night, spectra from 710 nm to 960 nm were secured for some of the objects. With both setups, the reciprocal dispersion was of 0.28 nm pix^-1, and the spatial scale .82 pix^-1. More details on the detector and gratings used, slit parameters, observing conditions and data reduction are described in paper I. The exposure times and the adopted slit position angles are listed in Table 1.

Table 1. Log of the observations.

The long-slit spectrum of each nebula was divided into a number of bins corresponding to spatial regions located at increasing distances from the centre of the object. In each region, average 1-D spectra were extracted by spatial binning. These 1-D spectra usually correspond to the central region of the nebulae, plus few symmetrical zones on each side of the central star. The central regions are referred to as c, while regions on the "positive" side (according to the oriented direction defined by the adopted position angle) are named p1, p2, etc., for increasing distances from the centre, respectively. Analogously, the regions on the "negative" side are called n1, n2, etc. The exact location of the middle point of each region and its extension are given in Table 2, and visualized in Fig. 1. The line fluxes, normalized to =100, and the absolute flux of H , are listed in Tables 4-16.

Table 2. The selected regions of the nebulae.

Fig. 1. The H +[NII] images of the nebulae; a drawing of the adopted slit position is superimposed on the images. North is at the top, East to the left. Slits are split in order to show the regions from which average 1-D spectra were extracted (see text). Images are from CS95.

© European Southern Observatory (ESO) 1998

Online publication: March 23, 1998
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