Point Spread Functions for the EUV channels of SDO/AIA Telescopes
I present the stray—light PSFs and their inverses characterized for the SDO/AIA EUV telescopes. The PSFs consist of a narrow Gaussian core, a diffraction component, and a diffuse component represented by the sum of a Gaussiantruncated Lorentzian and a shoulder Gaussian. The diffraction term was determined using the measured geometry of the diffraction pattern identified in flare images and the theoretically computed intensities of the principal maxima of the first few diffraction orders. The diffuse component was obtained by fitting its parameterized model using iterative forward—modelling of the lunar interior in the SDO/AIA images from the March~4, 2011 lunar transit.
The inverse-PSFs can directly be used to convolve the original Level--1 images to improve the stray light characteristics. Deconvolution significantly improved contrast in dark features such as miniature coronal holes, though the effect was marginal in bright features. On a percentage-scattering basis, the PSFs for SDO/AIA are better by a factor of two than that of the EUV telescope on board the TRACE mission. A preliminary analysis suggests that deconvolution alone does not affect DEM analysis of coronal loop segments with suitable background subtraction.