## 7 Conclusions and Further Remarks  
The sensor FASat-C NAOMI-1 has been cross-calibrated using SNOs collected over the Frenchman Flat calibration site. RapidEye-MSI's radiometric response was used to update the absolute gains of FASat-C NAOMI-1 multispectral bands. A multitemporal EO-1 Hyperion dataset was utilized to derive an SBAF, which has allowed the correction of one of the major sources of uncertainties in a cross-calibration study; leading to a substantial improvement in the degree of agreement between both sensors. The applied cross-calibration method will permit an adequate integration and a straightforward comparison of FASat-C and RapidEye data, as well as from other sensors, taking advantage of the higher joint revisit capability. For future cross-calibration tasks, the availability of high spectral resolution data, either in situ, airborne or satellite measurements, will be fundamental to perform the required adjustments to the data; particularly historical hyperspectral imagery, since it offers a more operational approach for deriving compensation factors (SBAF). As PICS are constantly monitored by a considerable amount of Earth observation satellites, FASat-C will continue acquiring data over such sites, incrementing the number of available observations for cross-calibration purposes. As far as Chile is concerned, it is our intention to obtain and assign additional resources to the exploration, characterization and use of Cal/Val sites, with emphasis on sites where field campaigns and inter-comparison studies with other satellite programs have already been performed [98; 99; 100; 101; 102; 103; 104]. Local indicators of spatial association have been essential for the definition of the calibration areas; as a consequence, they will provide a tool for the selection of specific areas inside the CEOS-WGCV endorsed sites, either instrumented or PICS, and for the study of Cal/Val areas in Chile. This first experience will lead to the exploration and integration of other vicarious calibration techniques, such as the reflectance based approach, with the aim of implementing a more comprehensive method for updating not only the absolute radiometric response of FASat-C NAOMI-1, but also of upcoming Chilean space observation sensors. In this sense, future Cal/Val activities of FASat-C will include data from instruments, such as Terra-ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), MODIS, ETM+ and L8-OLI (Operational Land Imager), among others, as proposed by [PERSON] et al. [105]. The authors would like to thank the Space Operations Group (GOE) and the Aerial Photogrammetric Service (SAF) of the Chilean Air Force (FACH), for supporting this study. Acknowledgements are extended to Blackbridge for providing RapidEye data and to Imagine-IT for their support. Finally, the authors would also like to acknowledge the United States Geological Service (USGS) for making the Hyperion data used in this work freely available. [PERSON] and [PERSON] conceived of the idea of this work and developed the method. [PERSON] and [PERSON] processed the data. [PERSON], [PERSON] and [PERSON] interpreted and analyzed the data and wrote the paper. The authors declare no conflict of interest. The following abbreviations are used in this manuscript: