Digisun: a tool to extract scientific data from sunspot drawings

DigiSun is a software developed at the Royal Observatory of Belgium to digitize and analyze sunspot drawings. It has been written in successive phases. The last phase of developement was done in 2018 with the re-designing and the rewriting of the program in Python. Although the program has been developed for the ROB needs, it is generic enough to be used by any obsevatory which has sunspot drawings.

Functionnalities

• Sunspot drawings display, variable image scale and image overlay (large grid in figure below)
• Calculation of the solar axis angles (P, B, L) via an in-house ephemeris module
• Correspondence between the pixel positions and the heliographic coordinates on the solar disk
• Recording of sunspot group parameters (number of spots, splitting, Zurich and McIntosh morphological classification).
• Measurement of the dipole positions and recording of the asymmetry leading/trailing
• Total area sunspot group measurement

All the parameters of the groups are then saved in an external database for relevant scientific analysis. In addition, it contains a functionality to perform the scanning of drawings making it a unique end-to-end tool to transform drawings into scientific data.

As an illustration, here is a screenshot of the drawing analyse page :

Installation

Steps to install the software: installation

Tutorials

A video showing how to analyse a drawing: here