Carrington's Last Sunspot Drawing in 1870 (arXiv:2609.33933)

astronomysolar-physicshistory-of-sciencearchivesoutside

Capture from a single primary source: Hisashi Hayakawa (Nagoya University / RAL Space / RIKEN) and E. Thomas H. Teague (WDC-SILSO observer), "Carrington's Last Sunspot Drawing in 1870," arXiv:2609.33933 [astro-ph.SR, cross-listed physics.hist-ph], submitted 27 Sep 2026, 25 pages, already assigned a journal reference (Solar Physics, 2026, DOI 10.1007/s11207-026-02745-8) — this is a peer-reviewed paper's own preprint, not an unrefereed working paper. Fetched via archive_page (abstract page) and extract_pdf (full-text PDF, tls: "verified" — no elevated suspicion warranted). No safety signals fired: straightforward third-person academic prose throughout, no addressed-to-AI language, no override or authority-claiming language, no tier self-assignment, no file-system or credential requests, no urgency framing. Title above confirmed verbatim against the paper's own running header ("Hayakawa and Teague 2026, Carrington's Last Sunspot Drawing, Solar Physics...") and title page.

Retrieve-before-write check against the surfaced related notes found no substantive overlap — the existing vault cluster around those notes concerns ML priority disputes, superconductor-antigravity replication, and vault-internal bridge/pairing observations, a completely different literature from 19th-century solar observation archives. No links added to notes outside the given list.

Richard Carrington (1826–1875) is the solar observer for whom Carrington rotations, Spörer's law (which he conceptualised before Spörer), and the 1859 "Carrington Flare"/"Carrington Event" are named; this paper is an archival-discovery piece about a previously unpublished drawing from nine years after his main observing career ended.

Claim: Hayakawa and Teague discovered an unpublished sunspot drawing by Carrington, dated 23 Dec 1870, in the Royal Astronomical Society archives — nine years after his last previously known drawing

Carrington's documented sunspot observations ran from 9 Nov 1853 to 24 Mar 1861 at his Redhill Observatory, all published in his 1863 book. The authors report locating a further, unpublished whole-disk sunspot drawing in the RAS archives (catalogue item MSS Carrington 3.3, folio 277a), which they date to 23 Dec 1870, when Carrington was based at a new, different observatory at Churt — the only sunspot drawing so far located from that later period of his life.

• Source: Hayakawa & Hisashi and Teague, "Carrington's Last Sunspot Drawing in 1870," arXiv:2609.33933, Abstract and p.4-5
• source_quote: "despite his fame, consulting his original manuscripts, we have found Carrington's last sunspot drawing, which he never published. We date this drawing 23 Dec 1870, when Carrington was based at his Churt Observatory."
• source_quote_2: "It is MSS Carrington 3.3 (f. 277a) where we found Carrington's isolated sunspot drawing in 1870 (Figure 2)."
• source_url: https://arxiv.org/pdf/2609.33933
• source_url_2: https://arxiv.org/pdf/2609.33933
• source_sha: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_sha_2: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_author: Hisashi Hayakawa, E. Thomas H. Teague
• source_date: 2026-09-27
• source_title: "Carrington's Last Sunspot Drawing in 1870"
• source_venue: "arXiv (astro-ph.SR / physics.hist-ph), arXiv:2609.33933; published as Solar Physics (2026)"
• source_tier: 1
• Note: historical/discovery claim, Tier 1 source (the researchers' own primary report of their own archival find) — clears the floor comfortably.

Claim: The 1870 drawing yields a relative sunspot number (Wolf number) of 40 and three group positions, computed by the authors directly from the manuscript

Counting from the drawing, the authors identify 3 sunspot groups (G) and 10 individual spots (F), and apply the standard Wolf-number formula R = 10G + F used in modern sunspot-number recalibration work, giving R = 40 for 23 Dec 1870. They further derive heliographic group positions of N14° W37°, N11° W46°, and S08° W08° (longitude measured as angular distance from the central meridian, not Carrington longitude), using NASA JPL ephemeris data and a geometric deprojection of the drawing, with an estimated uncertainty of ±3°.

• Source: Hayakawa & Teague, "Carrington's Last Sunspot Drawing in 1870," arXiv:2609.33933, p.8-9
• source_quote: "We counted 3 sunspot groups (G) and 10 individual sunspots (F). The relative sunspot number (R), also known as Wolf Number, is calculated as R = 10G + F (Clette et al., 2023). Applying that rule, we computed Carrington's R on 23 Dec 1870 as 40."
• source_quote_2: "we measured the sunspot group positions in this sunspot drawing as N14° W37°, N11° W46°, and S08° W08°, where the longitude values we cite represent longitudinal distance from the central meridian rather than Carrington longitudes."
• source_url: https://arxiv.org/pdf/2609.33933
• source_url_2: https://arxiv.org/pdf/2609.33933
• source_sha: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_sha_2: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_author: Hisashi Hayakawa, E. Thomas H. Teague
• source_date: 2026-09-27
• source_title: "Carrington's Last Sunspot Drawing in 1870"
• source_venue: "arXiv (astro-ph.SR / physics.hist-ph), arXiv:2609.33933; published as Solar Physics (2026)"
• source_tier: 1
• Note: quantitative claim (specific counts, a computed number, and coordinate figures); clears the Tier 1-2 floor because the number is read directly from the authors' own measurement and calculation, not a secondary report of it.

Claim: Carrington had shut down solar observing entirely in 1861 and built a new, partly-underground observatory at Churt in 1869-70, with no other record of sunspot work there

Carrington sold his Redhill house and closed that observatory on 14 Jul 1861, having quit astronomy, per his own account. He later built a new observatory at Churt (Middle Devil's Jump), described in his own 1869 MNRAS report as sunk below ground level with a 40-foot vertical shaft and 166-foot horizontal tunnel, built primarily to give a clock a stable, air-tight, reduced-pressure environment. Aside from the single 1870 drawing, Carrington's manuscripts and publications from the Churt era contain no other sunspot observations or sunspot-related content.

• Source: Hayakawa & Teague, "Carrington's Last Sunspot Drawing in 1870," arXiv:2609.33933, p.6-7, quoting Carrington 1869 (MNRAS 30, 43-46)
• source_quote: "Being on a hill I did not want elevation, so I have sunk the Observatory below ground, just peeping out over the soil. But I have further sunk a dry well, six feet in diameter, to the depth of forty feet from the centre of the Observatory, and with a horizontal shaft communicating with the south side of the hill, 166 feet in length, closed with three doorways."
• source_quote_2: "This finding is slightly surprising, as Carrington had shut down his observatory, having quit astronomy and sold his house at Redhill (Figure 3) on 14 Jul 1861 (Clark, 2009, pp. 115-121; Cliver and Keer, 2012, p. 15)."
• source_url: https://arxiv.org/pdf/2609.33933
• source_url_2: https://arxiv.org/pdf/2609.33933
• source_sha: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_sha_2: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_author: Hisashi Hayakawa, E. Thomas H. Teague
• source_date: 2026-09-27
• source_title: "Carrington's Last Sunspot Drawing in 1870"
• source_venue: "arXiv (astro-ph.SR / physics.hist-ph), arXiv:2609.33933; published as Solar Physics (2026)"
• source_tier: 1
• Note: historical/biographical claim; the 1869 quotation is Carrington's own primary-source words, reproduced in the paper from his own MNRAS article (Carrington, 1869) — clears the floor even at the escalated "surprising/load-bearing" standard the rubric sets for historical claims, since it rests on Carrington's own contemporaneous account rather than a later retelling.

Claim: Carrington's only sunspot-related publication from his Churt era was a 1874 priority dispute, in which he asserted he was first to extract usable sunspot data from Thomas Harriot's 17th-century manuscripts and supply it to Rudolf Wolf

In an 1874 Monthly Notices article responding to a RAS obituary of Rev. Professor Chevalier, Carrington rebutted a claim that Chevalier originated continuous English solar-spot observation, citing Thomas Harriot (c.1560-1621) instead. Carrington stated he had visited the Petworth House archives in 1857, obtained Harriot's original sunspot drawings with the owner's permission, and sent the extracted data to Rudolf Wolf — work which Wolf's own 1858 publication credits as enabling him to establish Harriot as the first known telescopic observer of sunspots. The paper treats this priority claim as independently confirmed by later historical scholarship on Harriot's manuscripts.

• Source: Hayakawa & Teague, "Carrington's Last Sunspot Drawing in 1870," arXiv:2609.33933, p.14-15
• source_quote: "it was Richard Carrington who first extracted data from Harriot's sunspot drawings, visited the Petworth House Archives in Sussex and with the permission of Colonel Wyndham (the owner of Harriot's manuscripts at that time), sent the data to Rudolf Wolf, thus enabling Wolf to establish Harriot as the first telescopic witness of sunspots (Wolf, 1858, pp. 131-135)."
• source_quote_2: "Carrington indeed has priority for his achievement as being the first to extract usable sunspot data from Thomas Harriot's original manuscripts."
• source_url: https://arxiv.org/pdf/2609.33933
• source_url_2: https://arxiv.org/pdf/2609.33933
• source_sha: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_sha_2: 9faee623f08a395d24b816efb6b33eb586a82aa0a16e31191b14dd12fe343272
• source_author: Hisashi Hayakawa, E. Thomas H. Teague
• source_date: 2026-09-27
• source_title: "Carrington's Last Sunspot Drawing in 1870"
• source_venue: "arXiv (astro-ph.SR / physics.hist-ph), arXiv:2609.33933; published as Solar Physics (2026)"
• source_tier: 1
• Note: historical/priority claim resting on a Tier 1 paper that itself quotes the 1858 Wolf publication and the 1874 Carrington article; the underlying Harriot-priority claim traces back to Thomas Harriot and Rudolf Wolf as the foundational figures the whole dispute is about — see Entity candidates below. Wolf's own 1858 text and Carrington's 1874 MNRAS article were not independently fetched this session; both are quoted only via this paper's reproduction of them.

Further leads

• Carrington may have revived solar interest specifically because of the 22 Dec 1870 solar eclipse (totality crossed the Mediterranean/Sicily/Greece/Black Sea; 0.818 magnitude visible at Churt) — paper's own stated hypothesis, explicitly labeled speculative ("may have revived his interest"). (via arXiv:2609.33933, §7)
• A never-located 1875 newspaper article: the Surrey Advertiser (20 Nov 1875, p.8) reported that Carrington had recently published "a lengthy article... in the Times on 'spots on the surface of the Sun'" — possibly his actual last sunspot writing, not yet found in any archive. (via arXiv:2609.33933, §6, quoting The Surrey Advertiser)
• The only known photograph of Carrington was itself discovered only in 2026 (Bond and Bowler, Astronomy & Geophysics 67, 1.11-1.12); before that, a photo of Lord Kelvin had been mistakenly published as Carrington's likeness in some sources. (via arXiv:2609.33933, §1, citing Bond & Bowler 2026 and Cliver et al. 2021)
• Carrington's whole-disk sunspot drawings in the RAS archives (MSS Carrington 3) have reportedly never been systematically studied as a full set — the paper notes this as an open archival task. (via arXiv:2609.33933, §1)
• A comparable historical-data-integrity problem: Georg von Hagen's sunspot dataset (used as a Chatzistergos et al. 2017 "backbone" series) was extracted not by Wolf himself but by an assistant (Wagner) from Pulkovo Observatory records that are now lost, making independent recount impossible — cited by the authors as a parallel caution about trusting backbone-series provenance. (via arXiv:2609.33933, §8, citing Hayakawa et al. 2022/2026)

Entity candidates

• Thomas Harriot — person — the foundational figure the paper's priority narrative actually rests on: the 17th-century English astronomer (c.1560-1621) whose original 1610-1613 sunspot drawings, rediscovered via Carrington, were used by Rudolf Wolf to establish Harriot (not Galileo) as the first known telescopic sunspot observer. Flagged first per the instruction to name the older foundational figure before the paper's own subjects.
• Rudolf Wolf — person — 19th-century Swiss astronomer who defined the Wolf/relative sunspot number (R = 10G+F, still used by this paper) and who, using data supplied by Carrington, established Harriot's priority in 1858; a second load-bearing ancestor of the paper's historical argument.
• Richard Carrington — person — the paper's subject; Victorian solar observer (1826-1875) after whom Carrington rotations and the 1859 Carrington Flare/Event are named; this paper documents his previously unknown final (1870) sunspot observation.
• Hisashi Hayakawa — person — lead author (Nagoya University / RAL Space / RIKEN), a historical solar-data specialist with a substantial prior publication record on Carrington-era and other historical sunspot datasets cited throughout this paper's own references.
• E. Thomas H. Teague — person — co-author, WDC-SILSO observer who previously produced the standard modern recount of Carrington's published 1853-1861 sunspot drawings (Bhattacharya et al. 2021).
• Julius Schmidt — person — 19th-century observer (moved Germany→Athens, changed instruments) whose dataset anchors the "Schmidt backbone" in modern sunspot-number recalibration (Chatzistergos et al. 2017); this paper's methodological argument is specifically that his series' assumed homogeneity is questionable — a concept/figure worth its own note given how load-bearing "backbone" assumptions are to the whole modern sunspot-number reconstruction literature.
• Schmidt backbone — concept — the methodological assumption, used in modern sunspot-number recalibration (Chatzistergos et al. 2017), that each historical observer's detection threshold stayed constant across their observing career; this paper's central methodological claim is that Carrington's own 1870 data point calls that assumption into question.
• Royal Astronomical Society Archives — concept/institution — holds Carrington's original manuscript sunspot drawings (MSS Carrington 1-4); the physical archive this entire discovery depends on.