Processing of SUVI Deep Exposures of the 'Middle Corona' at EUV Wavelengths

Observations of the solar corona outside of the fields of view of existing EUV instruments have been made by SDO/AIA and PROBA/SWAP with off-pointed imaging that demonstrate measurable EUV signal out to 2.5 solar radii. The Lockheed Martin SUVI team, in conjunction with the NOAA and NASA GOES program, performed off-pointed SUVI imaging of the middle corona to over 4 solar radii, coupled with long exposures and summing to maximize signal. A preliminary analysis shows that there is signal out to the edge of the extended field of view even during periods of low solar activity. In order to exploit these new image data, careful calibration and processing must be done to remove artifacts and to maximize the signal and reduce noise ratio as well as to enhance the rapidly diminished coronal emissivity at distances further from the Sun. We outline the calibration and enhancement algorithms used and show examples of processed image mosaics of the large scale corona.