SOLARNET Conference: The Many Scales of the Magnetic Sun

We present a method of reduction of the atmospheric transparency influence on ground-based spectroscopic solar data. During the observational campaign of May 2022 devoted to solar flares we encountered a complex task of data reduction. Data from FICUS wide band solar spectrometer located in Ondrejov Observatory were affected by variations of the atmospheric transparency. From the data itself it is impossible to reduce the transparency influence in different wavelengths. Since our goal is to find changes in different spectral regions, transparency effects have to be reduced. We expect the solar continuum enhancement of a few percent and this puts critical constraints on the proper data reduction. To achieve this goal we compared observed spectra with the catalog of solar spectrum and data from HSFA-2 narrow band solar spectrograph located nearby. Preliminary results will be discussed.