Summary: When trying to build a large set of SpectroPhotometric Standard Stars (SPSS) for calibrating Gaia BP/RP spectra and G-Band images to a few % in absolute flux, it is essential to maintain the maximum homogeneity in data quality, acquisition and treatment.This is especially true when data come from different observing sites around the globe and are obtained and treated by different persons. The Observation Protocols and the Data Reduction Protocols are sets of detailed instructions for observers and collaborators that participate in the large effort required. This Data Reduction Protocol concerns the pre-reduction of photometric data obtained during both the auxiliary (absolute and relative photometry aimed to exclude variable stars from the main list of candidate Primary and Secondary SPSS), and main (mainly spectroscopy, but also absolute photometry for the absolute flux calibration of SPSS spectra taken in non-photometric nights) campaigns.The reduction procedure to pre-reduce the imaging data is based on semi-automatic pipelines available inWiki-Bo (see text). Even if the reduction steps are similar for all the instruments used in our campaigns, in some cases particular attention or special instructions are required. These cases are described in detail in the Appendices.


Bibtex entry for this abstract:

   author = {S.~Marinoni and E.~Pancino and G.~Altavilla and others},
   title={{D}ata {R}eduction {P}rotocol for {G}round {B}ased {O}bservations of {S}pectro{P}hotometric {S}tandard {S}tars. {I}. {I}maging {P}re-reduction},
   institution={Osservatorio di Bologna, Italy},
   type={Technical Note}