Free Access

Fig. 2


Tracing of the centre of the Hg i arc line at λ = 4358.343 Å on the FORS2 detector in the spatial region where science spectra are recorded. Different colours and line-styles refer to calibration frames obtained on different days and with different positions of the retarder waveplate, as explained in the text. Note that black and red lines are practically superposed, but the line positions on 2011-05-07 are offset by ~0.08 px with respect to those measured on 2011-05-05 and 2011-05-06.

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.