Based on observations collected at the European Southern Observatory (ESO, La Silla and Paranal).

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Table 4 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/433/757

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...1,

Chercheur qualifié du FNRS, Belgique.

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... $3.0 \times [(2~\ln 2)^{-1/2} ~\it HWHM]$

For He 1304-1157, the radius was $2.5 \times [(2~\ln 2) ^{-1/2} {\it HWHM}]$ due to the presence of a cosmic-ray hit at larger radii.

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... deviation

Except the measurements for HD 251204 which disagree in both polarization degree and position angle from tabulated data, possibly indicating polarization variability (see also Weitenbeck 1999).

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... latitudes

Except FIRST J0809+2753 with $\vert b_{\scriptscriptstyle \rm II}\vert = 28.33\hbox{$^\circ$ }$ .

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... stars

We consider a single star per frame/field. In some cases this star is made up of the combination of several fainter stars from a given frame.

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... ours

There is also a good agreement between the polarization degrees (typically around 0.2-0.3%, cf. Fig. 2), provided that one considers distant stars in the Heiles catalogue, i.e. stars at distances $\geq$ 100-200 pc.

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... $\overline {u}_{\star }$

Different $\overline {q}_{\star }$ and $\overline {u}_{\star }$ are used for each observing run. Ideally, as suggested by the results in Fig. 1, one should have also computed $\overline {q}_{\star }$ and $\overline {u}_{\star }$ for $b_{\scriptscriptstyle \rm II}\ge 30^{\circ}$ and $b_{\scriptscriptstyle \rm II}\le -30^{\circ}$ separately. However this makes little difference since nearly all objects observed in a given run were either at $b_{\scriptscriptstyle \rm II}\ge 30^{\circ}$ or at $b_{\scriptscriptstyle \rm II}\le -30^{\circ}$ .

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... frames

We were also able to measure the polarization of 10 field galaxies with a reasonable accuracy. Within the uncertainties, their polarization (both in degree and angle) does not differ from the polarization of the field stars. This suggests that the contamination by interstellar polarization in our Galaxy is not significantly higher for objects at extragalactic distances.

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	1 Introduction
	2 The observations
	3 Data reduction
	4 The results
	5 Conclusions
	References