Free Access

Fig. 1


Distribution of the signal-to-noise (S/N) of the scientific spectra in our sample. The position of the slits is shown as red bars, and the colours of the polygon, calculated by Voronoi Tessellation, indicate the S/N according to the scale in the colour bar in the bottom left corner. Slits with white background were excluded from the analysis owing to their low quality (S/N< 10). Black lines show the V-band contours in the range from 20 to 23.5 mag arcsec-2 in intervals of 0.5 mag arcsec-2, from Arnaboldi et al. (2012). The geometry of the polygons is shown hereafter in all the other maps in this study.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.