• Gafeira, Ricardo
• Barata, T.
• Garcia, A.
• Pina, P.
• Carvalho, S.

Abstract

The Geophysical and Astronomical Observatory of the University of Coimbra (OGAUC) has a collection of solar observations (spectroheliograms) that span near nine decades, acquired uninterruptedly until today on a daily basis since 1926 and already in digital format. This extensive collection acquired with the same instrumentation must be processed altogether since its large temporal coverage can provide important inputs for the knowledge of the solar activity. Therefore, this work aims to evaluate the capability of some methods in the automatic detection of sunspots from spectroheliograms. The objective of this work is to define a strategic action, concerned with sunsposts detection, to be applied to all spectroheliograms datasets. The final detection results of different methods are compared to reference detections provided by an expert solar observer, in order to evaluate the performances on the detection of the contour of sunspots and also on the ability to differentiate the umbra and penumbra areas. According to the best detection performances (its accuracy but also computational time, among others), a processing chain will be implementedand applied to the whole data series of OGAUC.

Topics

• impedance spectroscopy