Sunspot Observations Made by Hallaschka during the Dalton Minimum

TL;DR

This paper analyzes historical sunspot observations by Hallaschka during the Dalton Minimum, enhancing the sunspot record for that period and confirming low solar activity, despite limitations in sunspot area data.

Contribution

It provides new historical sunspot counts from Hallaschka, filling observational gaps during the Dalton Minimum and comparing them with other contemporary records.

Findings

Hallaschka's sunspot counts align with other observers.

Sunspot areas and positions are too inaccurate for detailed analysis.

Confirms low solar activity during the Dalton Minimum.

Abstract

We present and analyse the sunspot observations performed by Franz I. C. Hallaschka in 1814 and 1816. These solar observations were carried out during the so-called Dalton minimum, around the maximum phase of the Solar Cycle 6. These records are very valuable because they allow us to complete observational gaps in the collection of sunspot group numbers, improving its coverage for this epoch. We have analysed and compared the observations made by Hallaschka with the records made by other contemporary observers. Unfortunately, the analysis of the sunspot areas and positions showed that they are too inaccurate for scientific use. But, we conclude that sunspot counts made by Hallaschka are similar to those made by other astronomers of that time. The observations by Hallaschka confirm a low level of the solar activity during the Dalton minimum.