Fig. 1. Short note and mirrored reproduction of the sunspot drawing with gray and red pencils of 9 July 1703 by Maria Eimmart (Eimmart Archive Collection 998, volume 35, folio 40). The heliographic grid corresponds to 8:41 UT. Blue thin circles mark digiti. The bipolar sunspot group is indicated by the red arrow (Vokhmyanin and Zolotova 2023).
Observations by Maria Eimmart
Maria Clara Eimmart (1676–1707) is a German astronomer, painter, and engraver. She is the daughter of Georg Christoph Eimmart and wife of Johann Heinrich Müller, a professor of astronomy at Altdorf (Bernardi 2016).
30–31 May and 9 July 1703
Three drawings by Maria Eimmart are stored in the Manuscript department of the National Library of Russia, St. Petersburg, Collection 998, volume 35, folios 37–40 (1, 2, 3, 4, 5, 6). The catalog record for these folios contains a question mark after her name. A comparison of the handwriting with letters by Maria Clara to Johann Jacob Scheuchzer in Zurich written in 1695 – 1697 (Eimmart 1695) shows little similarity with the observing folios considered here. There may be three reasons for the differences: i) the letters are written in German, whence using the Kurrent writing in contrast to the Latin observing notes, ii) the letters were more carefully written than the observing notes, and iii) the observations were made 6–8 years after the letters had been written.
We can also use the observed culminations of astronomical objects to determine the geographical latitude of the observer. The solar altitudes checked appear to favor a location 3 arcmin south of the Eimmart observatory. The nearby observatory at Altdorf (operated by Johann Christoph Sturm until 1703) is 4.3 arcmin south of the Eimmart observatory. However, since J.C. Sturm died in 1703, the observations cannot be by him, as they cover the period of February 1703 to April 1704.
The measurement errors at Eimmart's observatory were determined to be up to 4 arcmin, with an average of 1.66 arcmin (Gaab 2002). Their own latitude estimate of 49o27'20'' (von Murr, 1784) is very close to the modern value of 49o27'30'' though, but individual measurements may, of course, be of lesser quality. Therefore, the daily altitude measurements of objects may have also been made at Nürnberg. There is also the fact that G.C. Eimmart fell ill in 1703 before he died on 5 January 1704. This is confirmed by a letter to Flamsteed in October 1703, in which Eimmart apologizes for not sending observations because of illness, as well as a biography source saying that he had been ill for two years before he died (Gaab 2002). Therefore, it is well possible that his daughter took over the daily measurements of culmination altitudes. Finally, there are, in fact, notes (Scheuchzer 1691) with Latin block letters among the observations that resemble the Latin block letters on Maria’s (upside-down) drawing of the first-quarter Moon in a friendship book of Johann Jacob Scheuchzer sufficiently well that we conclude the observations in volume 35, folios 7–35, 37–40, and 45–51 were made by Maria Clara Eimmart (1, 2, 3, 4, 5, 6, 7, 8, 9).
The sunspot drawings are schematic, made with pencil. Short accompanying notes provide a date, an observing time, and a sketch of sunspots. Throughout the folios, there are a lot of defects of gray and various blots of reddish ink. On the solar disk, these defects look like artificial sunspots that are not easy to distinguish from real ones. Two drawings of 30 and 31 May 1703 are considered in Eustachio Manfredi, where they are compared with those by Hoffmann and Manfredi.
Figure 1a shows the observing note accompanying the drawing of 9 July 1703 saying that a major and a minor sunspot were observed on the Sun. An apparently bipolar sunspot group is sketched (marked by the red arrow). Similar mentions of the sunspots on 9 and 14 July 1703 were already shown by Hayakawa et al. (2021, Figure 4 therein) among the other astronomical notes of Maria Eimmart and provided one sunspot group observed on 9, 14, and 16 July 1703.
Below, we consider the observations of Eimmart's contemporaries made in June and July 1703. With reference to la Hire, Spoerer (1889) wrote that there were no sunspots on 7 July, but there was a group on 8 – 16 July at −19o latitude. From drawings by Derham (1703) and Gray (1703), we estimate the latitude of a sunspot group to be between −20o to −25o. Also, Derham mentioned that the sunspot group of 8 – 17 July 1703 had "remarkable appearance and variations". This note suggests that Maria Eimmart’s drawings depicted the location of sunspot groups schematically and not to scale.
Neuhäuser at al. (2018) translated a letter by Kirch: "On [1703] July 8 another sunspot was found, in the other inch from the ingress [eastern] limb. On July 10 and 11 there were three [spots]. On July 15 we only could see one spot (through very thick air) at the egress [western] limb. The first spot did not come back on the ingress limb." They got a broad solution for sunspot latitude: 7 ± 21o. This leads us to an assumption of more than one sunspot group.
Returning to Maria Eimmart's drawing, it is posited that she may have rotated the paper as one would in a notebook. Consequently, in order to establish the coordinates of the sunspots, it is necessary to invert the drawings. In Figure 1, a reproduction of the sunspot drawing of 9 July 1703 is shown. The original image was made with gray and red pencils. The boundaries of the disks are slightly misaligned. Circles of digiti (in blue) and heliographic grid (in gray) are added by us. Taking an equatorial synodic speed rotation as 13.3o d-1, we find that the red spot should have been about 2 inches from the eastern limb on 8 July and one inch from the western limb on 15 July, which is consistent with Kirch’s description. There is also a gray spot, which Spörer and Derham marked as a group at −20o and one more at 10o in the northern hemisphere. As a result, we got three groups, which Kirch apparently mentioned on 10 and 11 July 1703.
Two drawings of 30 and 31 May 1703 are considered in Manfredi.
Update from 2026 after analyzing La Hire's observations: A new look at Maria Eimmart's observation on 9 July 1703 reveals that it does not match any other observations. Therefore, we would caution against using her data until they are confirmed by other solar observations.