New sunspots and aurorae in the historical Chinese text corpus? Comments on uncritical digital search applications

Abstract

. However, we show strong shortcomings in the digital search technique as applied by them: almost all likely true sunspot and aurora records were presented earlier (e.g., Xu et al. 2000), which are not mentioned in those papers; the remaining records are dubious and often refer to other phenomena, neither spots nor aurorae (this also applies to Hayakawa et al. 2017c). The alleged aurorae in Hayakawa et al. (2015) and Kawamura et al. (2016) show a broad peak around full moon, not expected for aurorae. Hayakawa et al. (2017a) use the Korean report At night, the gate of heaven was opened (between AD 992 Dec 6 and AD 993 Jan 25, i.e., close to the 14 C variation AD 993/994) to estimate the Dst index of solar activity, even though the text does not fulfill any discriminative aurora criteria (except night-time). Most of the above publications include very few Chinese texts and translations, and their tables with abbreviated keywords do not allow the reader to consider alternative interpretations (the tables also do not specify which records mention night-time). We have compared some of their event tables with previously published catalogues and found various discrepancies. There are also intrinsic inconsistencies, misleading information (lunar phase for day-time events), and dating errors. We present Chinese texts and translations for some of their presumable new aurorae: only one can be considered a likely true aurora (AD 604 Jan); some others were selected on the sole basis of the use of the word light or rainbow. Several alleged new aurorae present observations beside the Sun during day-time. There are well-known comets among their presumable aurorae. We also discuss (a) whether heiqi ri pang can stand for black spot(s) on one side of or beside the sun, (b) the aurora color confusion in Hayakawa et al. (2015Hayakawa et al. ( , 2016, and (c) whether white and unusual rainbows can be aurorae.

Aurora Observations from the Principality of Transylvania from the 16th to the 18th Century CE

“…Likewise, another auroral display seems to have happened two weeks earlier: "On November 3, a figure of a great fiery man was seen in the sky." (Nösner, 1903). Furthermore, aurorae from Brasov are reported from six nights in February, one in March, and two in December (Rethly and Berkes, 1963).…”

“…Two years later, in 1607, it is reported from Halchiu in Transylvania: "On January 18, the sky burned very brightly from 5 to 9 [p.m.]" (Nösner, 1903). Northern lights were also seen the same year on 17 November in Kaufbeuren in Bavaria (Pilgram, 1788).…”

“…However, we conclude that selective perception and a shift in the focus of interest over decades and centuries did have a more considerable influence on the records than the actual frequency or manifestation of auroral displays. Neuhäuser, Neuhäuser, and Chapman (2018) have designed a five-point scheme aiming to distinguish genuine auroral observations from false ones, i.e. confusion with atmospheric phenomena, comets, meteors, etc.…”

Critical comments on publications by S. Hoffmann and N. Vogt on historical novae/supernovae and their candidates

“…Such an objective operation may also help to avoid misclassifications and biases. For each astrophysical application, one needs only reliable candidates and well‐constrained positions—just as “white rainbows” are not useful as aurora candidates for solar activity studies, because they are real fog‐bows or night‐time rainbows (see Neuhäuser et al 2018a), objects with extension and/or movement across the sky, like those among their list of “24 most promising events” (P3 Table 2), are obviously comets, not nova candidates.…”

A new approach to generate a catalogue of potential historical novae

“…During the last 10 years, several scholars have used historical data to draw conclusions on astrophysical questions, for example, concerning the development of close binary systems. For historical supernovae, this has been achieved for several decades (starting with Schlier ; Baade ), and for solar activity as well as for improving orbital elements of comets by usage of historical data, for example, Neuhäuser et al () and Neuhäuser et al () also proved this concept to contribute to the current state of research. Thus, the idea of using old data caused the interest in research on cataclysmic variables (CVs) culminating in papers by Shara+ in the recent years (Shara et al ; Shara et al ; Shara et al ).…”