3-color photometry of a sunspot using speckle masking techniques

Abstract

A three-colour photometry is used to deduce the temperature of sunspot fine-structures. Using the Speckle-Masking method for image restoration, the resulting images (one per colour and burst) have a spatial resolution only limited by the telescope's aperture, i.e. 95km (blue), 145 km (red) and 180km (infrared). Absolute intensities were de- rived by normalization to the undisturbed surrounding photosphere. For each image point the brightness temperature is computed by assuming black body radiation. The resulting three images give consistent tem- perature information which prooves the photometric correctness of the Speckle Masking Method. The thus obtained temperatures for various sunspot fine-structures are compared with earlier data.