Effect of Stray Light Correction of Extreme-ultraviolet Solar Images in Tomography

PAUL SHEARER; ALBERTO M. VÁSQUEZ; DIEGO G. LLOVERAS; RICHARD A. FRAZIN

San Juan

Congreso; 59ª Reunión Anual de la Asociación Argentina De Astronomía; 2016

Asociación Argentina de Astronomía

The Extreme UltraViolet Imager (EUVI) telescope on board the Solar TErrestrial RElations Observatory (STEREO) mission provides extreme-ultraviolet (EUV) coronal images of the full Sun. Using time series of EUV images, the differential emission measure tomography (DEMT) technique allows determination of the three-dimensional (3D) distribution of the coronal electron density and temperature in the inner corona. EUV images are affected by stray light contamination which can be effectively removed if the point-spread function (PSF) of the instrument is well determined, as it is the case for EUVI. We show the results of a detailed analysis of the impact of EUVI stray light removal in DEMT results. To this end we analyze Carrington Rotation (CR)-2081 during the last solar minimum, characterized by a highly axisymmetric coronal structure. We find that stray light decontamination of EUVI images implies a systematic decrease of the derived electron density scale height and a systematic increase of the derived coronal base density, while its effect on the derived temperature is not systematic neither significant. We detail the results of the analysis in quantitative fashion