A large variation in 14 C around AD 775 has been considered to be caused by one or more solar super-flares within one year. We critically review all known aurora reports from Europe as well as the Near, Middle, and Far East from AD 731 to 825 and find 39 likely true aurorae plus four more potential aurorae and 24 other reports about halos, meteors, thunderstorms etc., which were previously misinterpreted as aurorae or misdated; we assign probabilities for all events according to five aurora criteria. We find very likely true aurorae in AD 743, 745, 762, 765, 772, 773, 793, 796, 807, and 817. There were two aurorae in the early 770s observed near Amida (now Diyarbakir in Turkey near the Turkish-Syrian border), which were not only red, but also green-yellow - being at a relatively low geo-magnetic latidude, they indicate a relatively strong solar storm. However, it cannot be argued that those aurorae (geo-magnetical latitude 43 to 50 deg, considering five different reconstructions of the geo-magnetic pole) could be connected to one or more solar super-flares causing the 14 C increase around AD 775: There are several reports about low- to mid-latitude aurorae at 32 to 44 deg geo-magnetical latitude in China and Iraq; some of them were likely observed (quasi-)simultaneously in two of three areas (Europe, Byzantium/Arabia, East Asia), one lasted several nights, and some indicate a particulary strong geo-magnetic storm (red colour and dynamics), namely in AD 745, 762, 793, 807, and 817 - always without 14 C peaks. We use 39 likely true aurorae as well as historic reports about sunspots together with the radiocarbon content from tree rings to reconstruct solar activity: From about AD 733 to 823, we see at least nine Schwabe cycles ...Comment: 24 pages with 1 table and 2 figures, paper to appear in Astronomical Notes 24 Apr 201

Given that a strong 14C variation in AD 775 has recently been suggested to be due to the largest solar flare ever recorded in history, it is relevant to investigate whether celestial events observed around that time may have been aurorae, possibly even very strong aurorae, or otherwise related to the 14C variation (e.g. a suggested comet impact with Earth's atmosphere). We critically review several celestial observations from AD 757 to the end of the 770s, most of which were previously considered to be true, and in some cases, strong aurorae; we discuss in detail the East Asian records and their wording. We conclude that probably none among the events after AD 770 was actually an aurora, including the event in AD 776 Jan, which was misdated for AD 774 or 775; the observed white qi phenomenon that happened "above the moon" in the south-east was most probably a halo effect near the full moon - too late in any case to be related to the 14C variation in AD 774/5. There is another report of a similar (or identical) white qi phenomenon "above the moon", reported just before a comet observation and dated to AD 776 Jan; the reported comet observed by the Chinese was misdated to AD 776, but actually sighted in AD 767. Our critical review of East Asian reports of aurorae circa AD 775 shows some very likely true Chinese auroral displays observed and reported for AD 762; there were also several events prior to AD 771 that may have been aurorae but are questionable.Comment: 15 pages with 4 figure

Hoyt & Schatten (1998) claim that Simon Marius would have observed the sun from 1617 Jun 7 to 1618 Dec 31 (Gregorian calendar) all days, except three short gaps in 1618, but would never have detected a sunspot – based on a quotation from Marius in Wolf (1857), but mis‐interpreted by Hoyt & Schatten. Marius himself specified in early 1619 that for one and a half year... rather few or more often no spots could be detected... which was never observed before (Marius 1619). The generic statement by Marius can be interpreted such that the active day fraction was below 0.5 (but not zero) from fall 1617 to spring 1619 and that it was 1 before fall 1617 (since August 1611). Hoyt & Schatten cite Zinner (1952), who referred to Zinner (1942), where observing dates by Marius since 1611 are given but which were not used by Hoyt & Schatten. We present all relevant texts from Marius where he clearly stated that he observed many spots in different form on and since 1611 Aug 3 (Julian) = Aug 13 (Greg.) (on the first day together with Ahasverus Schmidnerus); 14 spots on 1612 May 30 (Julian) = Jun 9 (Greg.), which is consistent with drawings by Galilei and Jungius for that day, the latter is shown here for the first time; at least one spot on 1611 Oct 3 and/or 11 (Julian), i.e. Oct 13 and/or 21 (Greg.), when he changed his sunspot observing technique; he also mentioned that he has drawn sunspots for 1611 Nov 17 (Julian) = Nov 27 (Greg.); in addition to those clearly datable detections, there is evidence in the texts for regular observations. For all the information that can be compared to other observers, the data from Marius could be confirmed, so that his texts are highly credible. We also correct several shortcomings or apparent errors in the database by Hoyt & Schatten (1998) regarding 1612 (Harriot), 1615 (Saxonius, Tard´e), 1616 (Tard´e), 1617–1619 (Marius, Riccioli/Argoli), and Malapert (for 1618, 1620, and 1621). Furthermore, Schmidnerus, Cysat, David & Johann Fabricius, Tanner, Perovius, Argoli, and Wely are not mentioned as observers for 1611, 1612, 1618, 1620, and 1621 in Hoyt & Schatten. Marius and Schmidnerus are among the earliest datable telescopic sunspot observers (1611 Aug 3, Julian), namely after Harriot, the two Fabricius (father and son), Scheiner, and Cysat. Sunspots records by Malapert from 1618 to 1621 show that the last low‐latitude spot was seen in Dec 1620, while the first high‐latitude spots were noticed in June and Oct 1620, so that the Schwabe cycle turnover (minimum) took place around that time, which is also consistent with the sunspot trend mentioned by Marius and with naked‐eye spots and likely true aurorae. We consider discrepancies in the Hoyt & Schatten (1998) systematics, we compile the active day fractions for the 1610s, and we critically discuss very recent publications on Marius which include the following Maunder Minimum. Our work should be seen as a call to go back to the historical sources. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Galactic novae and supernovae can be studied by utilizing historical observations, yielding explosion time, location on sky etc. Recent publications by Hoffmann & Vogt present CVs, supernova remnants, planetary nebulae etc. as potential counterparts based on their list of historically reported transients from the Classical Chinese text corpus. Since their candidate selection neglects the state-of-the-art (e.g. Stephenson & Green), and since it includes ‘broom stars’ and ‘fuzzy stars’, i.e. probable comets, we investigate their catalogue in more detail. We discuss here their two highlights, the suggestion of two ‘broom star’ records dated AD 667 and 668 as one historical supernova and of the ‘guest star’ of AD 891 as recurrent nova U Sco. The proposed positional search areas are not justified due to translation and dating problems, source omission, as well as misunderstandings of historical Chinese astronomy and unfounded textual interpretations. All sources together provide strong evidence for comet sightings in both AD 668 and 891 – e.g., there are no arguments for stationarity. The AD 667 record is a misdated doublet of 668. Our critique pertains more generally to their whole catalogue of ‘24 most promising events’: their speculations on counterparts lack a solid foundation and should not be used in follow-ups.

The interpretation of the strong 14 C variation around AD 775 as one (or several) solar super-flare(s) by, e.g., Usoskin et al. (2013) is based on alleged aurora sightings in the mid AD 770s in Europe: A red cross/crucifix in AD 773/4/6 from the Anglo-Saxon Chronicle, inflamed shields in AD 776 (both listed in the aurora catalogue of Link 1962), and riders on white horses in AD 773 (newly proposed as aurora in Usoskin et al. 2013), the two latter from the Royal Frankish Annals. We discuss the reports about these three sightings in detail here. We can show that all three can be interpreted convincingly as halo displays: The red cross or crucifix is formed by the horizontal arc and a vertical pillar of light (either with the Sun during sunset or with the moon after sunset); the inflamed shields and the riders on white horses were both two mock suns, especially the latter narrated in form of a Christian adaptation of the antique dioscuri motive. While the latter event took place early in AD 774 (dated AD 773 in Usoskin et al. 2013), the two other sightings have to be dated AD 776, i.e. anyway too late for being in connection with a 14 C rise that started before AD 775. We also sketch the ideological background of those sightings and there were many similar reports throughout that time. In addition, we present a small drawing of a lunar halo display with horizontal arc and vertical pillar forming a cross for shortly later, namely AD 806 June 4, the night of full moon, also from the Anglo-Saxon Chronicle; we also show historic observations of halo phenomena (mock suns and crosses) from G. Kirch and Hevelius -and a modern photograph.