Summary: When building a large set of ground based Spectro-Photometric Standard Stars (SPSS) for calibrating Gaia BP/RP spectra and G-band images to a few percent in absolute flux, it is essential to maintain the maximum homogeneity in data quality, acquisition and treatment. The procedure followed to pre-reduce the data, extract 1D spectra and perform the wavelength calibration is here described step by step. This procedure can be applied to any telescope, with a few exceptions: special "tips" are discussed for the CAFOS@CAHA2.2 and DOLoReS@TNG instruments in the Appendices.


Bibtex entry for this abstract:

   author = {G.~Cocozza and G.~Altavilla and J. M.~Carrasco and others},
   title={{D}ata {R}eduction {P}rotocol for {G}round {B}ased {O}bservation of {S}pectrophotometric {S}tandard {S}tars. {I}{I}. {S}pectroscopy {P}re-reduction up to extraction and wavelength calibration},
   institution={Osservatorio di Bologna, Italy},
   type={Technical Note}