Sunspot data
To define sunspot positions, we applied two methods (see Heliocoordinates). Both of them only optimize latitudes of sunspots, omitting their longitudinal displacement. The first one (Method I) exploits the time of observation provided by the observer. Another method (Method II) to extract sunspot positions does not take into account time of observation. Its goal is to minimize the cumulative latitude dispersion of sunspots.
The question arises: the results of which method are more relevant? Both methods have their advantages, nevertheless, in general, we would recommend exploiting both sunspot latitudes and longitudes from Method I. Method II itself is not aimed to precisely define the time of observation, but gives the best image rotation to define an average picture of sunspot positions. Results of Method II became more relevant comparing to those of Method I, if they were derived from small schematic drawings or in the case of large uncertainties, e.g. if the drawings were made without a projection apparatus. In these cases, sunspot data should be taken with extreme care.
provides positions and areas of sunspot groups
provides daily sunspot areas
provides number of groups and sunspots (as many as we have counted, without normalization factors)
|
Observer |
Sunspots |
|
Groups |
|
Ref |
| Thomas Harriot Dec 1610 – Jan 1613 |
Method I Method II |
 |
 |
 |
|
| Lodovico Cardi known as Cigoli Febr – May Aug 1612 |
Method I Method II |
 |
 |
 |
|
| Galileo Galilei Febr – May 1612 Aug 1612 |
Method I Method II |
 |
 |
 |
|
| Galileo Galilei May – Jul 1612 |
Method II |  |
 |
 |
|
| Sigismondo di Cologna 6 Sept – 9 Oct 1612 |
Method I Method II |
 |
 |
 |
|
| Fabio Colonna 1 Aug – 30 Sept 1613, 3 Oct 1614; Christoph Scheiner 1 Aug 1613 |
Method I Method II |
 |
 |
 |
|
| Petrus Saxonius 5–27 Mar 1616 |
Method II |  |
 |
 |
|
| Pierre Gassendi 1633 – 1638 |
Method II |  |
 |
 |
|
| Robert Boyle 7 May – 4 Jun 1660 |
Method I |  |
 |
 |
|
| Jo |