Sunspot Numbers from ISOON: A Ten-Year Data Analysis

TL;DR

This paper compares ten years of sunspot numbers obtained visually and digitally from ISOON data, highlighting the advantages of digital imagery for solar activity analysis.

Contribution

It provides a comprehensive comparison between visual and digital sunspot counting methods using a decade of ISOON data, demonstrating the benefits of digital imaging.

Findings

Digital images offer more consistent sunspot counts.

Digital method reduces observer bias.

Enhanced accuracy in solar activity monitoring.

Abstract

Sunspot numbers are important tracers of historical solar activity. They are important in the prediction of oncoming solar maximum, in the design of lifetimes of space assets, and in assessing the extent of solar-radiation impact on the space environment. Sunspot numbers were obtained visually from sunspot drawings. The availability of digital images from the US Air Force Improved Solar Optical Observing Network (ISOON) prototype telescope concurrent to observer-dependent sunspot numbers recorded at the National Solar Observatory (NSO) has provided a basis for comparing sunspot numbers determined from the two methods. We compare sunspot numbers from visual and digital methods observed nearly simultaneously. The advantages of digital imagery are illustrated.