A Brief Visit from a Red and Extremely Elongated Interstellar Asteroid
Nature, 2017 · paper · Astronomy
Reports observations of the first known interstellar asteroid, A/2017 U1, which passed briefly through the Solar System. The title states the object is red and extremely elongated; the text provided does not include the abstract's details.
Checked: PDF from europepmc.org, fetched 4 Oct 2026. Page numbers are those of that PDF.
4 findings
Substance "The 3σ (5σ) limits correspond to surface brightnesses of g = r =30.4 (29.8) ± 0.05 mag arcsec−2 ... up to 13/8 g (8/4 g), at the 3σ (5σ) level": the fainter 3σ limit is given the larger dust mass, the reverse of what the limits imply.
- p. 9 Methods, Assessment of lack of activity, second paragraph
up to 13/8 g (8/4 g), at the 3σ (5σ) level
- p. 9 Same paragraph, surface-brightness limits
g = r =30.4 (29.8) ± 0.05 mag arcsec−2
Only the authors can say what is right here.
Judge's note: Page 9 image reads as quoted. Under the stated 'same assumptions', dust mass scales with flux, so the 5σ mass should be 5/3 times the 3σ mass. The printed pairs go the other way (8/13 = 0.62, 4/8 = 0.5). The slash pairs are the two albedo/density cases, as in the preceding '0.5/0.3 kg' (ratio 1.67, matching 13/8 = 1.6), so the reading of parentheses as sigma level is the only one available. 8 × 5/3 = 13.3, so the two pairs look swapped. No statement elsewhere explains it. The authors need to confirm which pair belongs to which level.
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Substance "objects with H < 19 assuming an albedo pV = 0.04 ... (corresponding roughly to objects with diameters > 0.5 km diameter)" and "H < 19 (> 0.5 km diameter)" conflict with "H < 22 (about 250 m diameter assuming pV = 0.04)": H = 19 at that albedo is about 1 km diameter. The first phrase also repeats "diameter".
- p. 10 Methods, Estimating the interstellar object number density
roughly to objects with diameters > 0.5 km diameter
- p. 10 Same section
< 19 (> 0.5 km diameter) size to H < 22
- p. 10 Same section, end
H < 22 (about 250 m diameter assuming pV = 0.04)
- p. 10 Methods, same section
< 19 (> 0.5 km diameter) size
Only the authors can say what is right here.
Judge's note: Page 10 image reads as quoted in all three places. At a fixed albedo, 3 magnitudes in H is a factor 10^0.6 = 3.98 in diameter, so 250 m at H = 22 implies about 1.0 km at H = 19; 0.5 km is the radius. The paper's own HV = 22.4 giving a 102 m radius (page 8) agrees with the 250 m figure. Both statements specify pV = 0.04, and nothing in the text explains the factor of two. The internal inconsistency needs no outside formula. Whether the fix is '1 km diameter' or '0.5 km radius' is for the authors. The duplicated word 'diameter' is a separate S4 correction.
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Reference or label "This is remarkably close to the mean motion of stars in the solar neighborhood12" cites reference 12, "Bus SJ, Binzel RP. 2002; Phase II of the Small Main-Belt Asteroid Spectroscopic Survey", which is an asteroid spectroscopy paper, not a stellar-kinematics source.
- p. 4 Main text, paragraph on incoming velocity
of stars in the solar neighborhood12
- p. 12 Reference list, entry 12
Bus SJ, Binzel RP. 2002; Phase II of the Small Main-Belt Asteroid Spectroscopic Survey
- p. 17 Figure 4 caption
with D-type asteroids12 and comets
- p. 4 citation of reference 12
the mean motion of stars in the solar neighborhood
Only the authors can say what is right here.
Judge's note: Superscript 12 is clear on the page 4 image and entry 12 was read on page 12. The same reference is used appropriately in the Figure 4 caption ('D-type asteroids12', page 17 text). The citation is also out of first-citation order (8, 9, 12, 10, 11), and none of the 29 entries concerns stellar kinematics (entry 4, Jeans 1919, is cited for ellipsoid lightcurve amplitude), so the intended reference appears to be missing. Only the authors can supply it.
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Reference or label "A Moffat function25 was adjusted to an average profile" cites ref. 25, "Fulle M, 40 colleagues. 2015; Density and Charge of Pristine Fluffy Particles from Comet 67P/Churyumov-Gerasimenko", which is not a source for the Moffat profile.
- p. 9 Methods, Assessment of lack of activity
function25 was adjusted to an average profile
- p. 12 Reference list, entry 25
Fulle M, 40 colleagues. 2015; Density and Charge of Pristine Fluffy Particles from Comet 67P/
- p. 9 citation of reference 25
by averaging its flux in annuli. A Moffat function
- p. 12 reference list, entry 25
Fulle M, 40 colleagues. 2015; Density and Charge of Pristine
Only the authors can say what is right here.
Judge's note: Page 9 image shows superscript 25 after 'Moffat function' and again after 'Rosetta mission' a few lines later. Reference 25 on page 12 is the Rosetta dust-particle paper, which fits the second use only. No entry in the list (checked 1-28 on page 12) is a Moffat or point-spread-function reference, so the first citation is misplaced or a reference is missing. The authors must supply the intended one.
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18 minor (typos and the like; most checked by the judge only)
Reference or label Inside the Methods subsection 'Survey strategy improvements': "increasing the survey depth, sky coverage rate, and search strategies (see Methods)". The pointer refers to the section it sits in.
- p. 6 Methods, Survey strategy improvements
sky coverage rate, and search strategies (see Methods)
- p. 6 Methods, Survey strategy improvements
search strategies (see Methods)
Judge's note: Page 6 image: the sentence is under the Methods heading 'Survey strategy improvements'. No other Methods subsection discusses search strategies; the number-density section mentions survey depth only as a scaling factor. Looks like a leftover from text moved out of the main body. Harmless to the reader.
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Wording "an absolute magnitude of HV = 22.4 ... Using a cometary albedo of p = 0.04 yields an effective radius of 102 ± 4 m": the standard H–albedo–diameter relation gives about 110 m for these inputs.
- p. 8 Methods, Shape and size
HV = 22.4
- p. 8 Methods, Shape and size
of p = 0.04 yields an effective radius of 102 ± 4 m
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: the standard relation D = 1329 km × 10^(−H/5) / sqrt(p). Page 8 prints HV = 22.4, p = 0.04 and 102 ± 4 m. With 10^(−4.48) = 3.3113e-5 the radius is about 110 m, two quoted errors above 102 m; 102 m needs H of about 22.56. The paper does not give the formula or solar constant it used, and the stated error is from magnitude uncertainty only, so the authors may have used an unrounded H or a different constant. Only they can say.
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Typo Affiliation 2 ends "00044 Frascati (RM), Italy INAF" and affiliation 3 begins "Osservatorio Astronomico di Roma": the word "INAF" is stranded at the end of affiliation 2 instead of opening affiliation 3.
- p. 1 Affiliations 2 and 3
00044 Frascati (RM), Italy INAF
Judge's note: Page 1 image shows 'Italy INAF' at the end of the affiliation 2 line and affiliation 3 starting with 'Osservatorio'. It is printed that way, not a text-layer artefact. That INAF belongs with the Osservatorio is the natural reading of the layout.
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Typo Author contributions (p. 1): "T.B. helpd with Keck observations." should read "helped".
- p. 1 Author contributions footnote
T.B. helpd with Keck observations
- p. 1
T.B. helpd with Keck observations.
- p. 1 Author contributions
T.B. helpd with Keck
Judge's note: The page-1 image shows 'helpd' in the author contributions paragraph. It is a plain misspelling.
Second check: another model agreed
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Typo Author contributions: "L.D. Contributed to writing the paper." has a capital C mid-sentence, and "Did the sublimation modeling." is a sentence fragment with no subject.
- p. 1 Author contributions
L.D. Contributed to writing the paper.
- p. 1 Author contributions
Did the sublimation modeling.
Judge's note: Both are printed on page 1. The fragment follows the K.J.M. sentence, so the implied subject is K.J.M.; this is cosmetic, not a real attribution ambiguity.
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Typo Unmatched closing parentheses: "corresponding to a spectral slope of Sv = 23±3%/100nm), are consistent" (page 3; the bracket opened before 'g-r' is already closed after '0.20)') and "Rapid Response System15) is a 1.8 m" (page 6). Also "1.668 10−3 kg/s" (page 10) lacks a multiplication sign.
- p. 3 Main text, colours sentence
Sv = 23±3%/100nm), are consistent
- p. 3
corresponding to a spectral slope of Sv = 23±3%/100nm), are consistent
- p. 3 Results, colours
Sv = 23±3%/100nm)
- p. 3 Colors sentence
spectral slope of Sv = 23±3%/100nm)
Judge's note: All three are printed as quoted on the page images. The other items bundled into this cluster ('helpd', 'billions of year', 'will may become') are real but are covered by C002 and C012.
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Typo The term is spelled three ways: "Light-curve observations" (abstract), "lightcurve" (most of the text) and "light curve" (pages 6 and 8).
- p. 2 Abstract
Light-curve observations of ‘Oumuamua
- p. 3 Main text
re-phased lightcurve
Judge's note: Seen on pages 2, 3, 6 and 8. A style inconsistency only.
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Typo "has been orbiting the Galaxy for billions of year cannot be ruled out" (page 4): 'year' should be 'years'. Also "it is being upgraded and will may become part of work for a graduate thesis" (page 11): 'will may'.
- p. 4 Main text, velocity paragraph
orbiting the Galaxy for billions of year
- p. 4
orbiting the Galaxy for billions of year cannot be ruled out.
- p. 11 Code availability
will may become part of work
- p. 4 Discussion
billions of year
Judge's note: Both read on the page images. On page 4 the line ends with 'year' and the next begins 'cannot', so it is not an extraction artefact.
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Typo Methods (p. 5): "Two additional wP1-band -band pre-discovery images" has '-band' duplicated.
- p. 5 Methods, Discovery and orbit determination
-band -band pre-discovery images
- p. 5
Two additional wP1-band -band pre-discovery images from 2017
- p. 5 Methods, Discovery and orbit determination
Two additional wP1-band -band pre-discovery images
- p. 5 Methods, discovery
wP1-band -band pre-discovery images
Judge's note: The page-5 image shows 'wP1-band -band pre-discovery images' in the running text. The duplication is printed, not an extraction artefact. The 'as as' item cited here is handled under C024.
Second check: another model agreed
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Typo Unmatched closing parenthesis: "The Panoramic Survey Telescope and Rapid Response System15) is a 1.8 m diameter wide field astronomical imaging and data processing facility".
- p. 6 Methods, Pan-STARRS1
Rapid Response System15) is a 1.8
- p. 6
The Panoramic Survey Telescope and Rapid Response System15) is a
- p. 6 Discovery and characterization observations
Panoramic Survey Telescope and Rapid Response System15)
Judge's note: Page 6 image shows 'System' followed by superscript 15 and a ')' with no opening parenthesis anywhere in the sentence. Probably a remnant of '(Pan-STARRS1; ref)'.
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Typo Backtick instead of the opening quote, and missing space after the full stop: "none were found.`Oumuamua was at a heliocentric"; a stray mark also appears in the subscript "g`Oumuamua = 22.5" on page 9.
- p. 6 CFHT paragraph
none were found.`Oumuamua was at a heliocentric
- p. 9 Assessment of lack of activity
g`Oumuamua = 22.5
Judge's note: Page 6 image shows 'found.`Oumuamua' with a grave accent and no space, unlike the ‘ used elsewhere on the same page. On page 9 the subscripted label shows a small stray mark between g and 'Oumuamua'. Both are visible in the rendered pages, so not an extraction artefact.
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Typo "to cover the full spectra range" should read "full spectral range".
- p. 7 Methods, Keck 2 Telescope
to cover the full spectra range
Judge's note: Page 7 image, Keck 2 paragraph, prints 'full spectra range'.
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Typo Lower-case proper noun: "the Sloan Digital Sky survey21" versus "Sloan Digital Sky Survey (SDSS)" earlier on the same page.
- p. 7 Visual-band CCD data reduction
the Sloan Digital Sky survey21
- p. 7 Gemini South paragraph
Sloan Digital Sky Survey (SDSS)
Judge's note: Page 7 image shows both forms. The second is a proper name and should be capitalised; 'survey' follows 'PS1 ... 3π survey' on the same line, which probably caused it.
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Typo Literal LaTeX tilde left in the text: "Rotation periods were scanned in the range from 2 to 20~h".
- p. 8 Methods, Solving for the rotation period and colors
in the range from 2 to 20~h
- p. 8 Solving for the rotation period
from 2 to 20~h
Judge's note: Page 8 image shows '20~h' with the tilde printed between number and unit. It is a non-breaking-space markup remnant; the range is exact, not approximate.
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Typo Methods, Shape and size (p. 8): "cannot be distinguished by the lightcurve as as they produce the same cross-section" has 'as' duplicated.
- p. 8 Methods, Shape and size
by the lightcurve as as they produce
- p. 8
distinguished by the lightcurve as as they produce the same cross-section
- p. 8 Shape and size
cannot be distinguished by the lightcurve as as they produce
- p. 8 Methods, shape
as as they produce the same
Judge's note: The page-8 image shows 'as as' on a single line. It is a duplicated word.
Second check: another model agreed
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Typo Full stop instead of a comma: "closer to the Sun than 1 au. i.e. interior to Earth’s orbit."
- p. 10 Methods, Estimating the interstellar object number density, last sentence
the Sun than 1 au. i.e. interior to Earth’s orbit.
Judge's note: Page 10 image shows 'than 1 au. i.e. interior to Earth's orbit.' The full stop leaves a fragment; the main text on page 5 has the same idea with a comma ('within 1 au of the Sun, that is, interior to Earth's orbit').
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Typo Code availability (p. 11): "it is being upgraded and will may become part of work for a graduate thesis" has two modal verbs; one should be deleted.
- p. 11 Code availability, continued
upgraded and will may become part of work
- p. 11
it is being upgraded and will may become part of work
- p. 11 Code availability
will and may become part of work for a graduate thesis
- p. 11 Code availability
will may become part of work for a graduate thesis
Judge's note: The page-11 image shows 'will may become'. This is an editing leftover. The quote 'will and may' given by one reviewer is not on the page.
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Typo Ref. 4 prints "Problems of cosmogony and stellar dynamics Cambridge. University press; 1919. 1919": year duplicated and publisher mis-punctuated. Refs 5 and 27 have misplaced year formatting ("Pravec P. 2009; The asteroid lightcurve database.", "#210. 13: 2012;").
- p. 12 Reference list, entry 4
dynamics Cambridge. University press; 1919. 1919
- p. 12 Ref. 4
University press; 1919. 1919
- p. 12 Ref. 5
Warner BD, Harris AW, Pravec P. 2009; The asteroid lightcurve database.
- p. 12 Ref. 27
#210. 13: 2012;
Judge's note: Viewed the reference list on page 12. Ref. 4 is exactly as quoted: "Cambridge. University press" is split by a full stop and the year appears twice. Ref. 5 has the year with a semicolon before the title, and ref. 27 ends "#210. 13: 2012;". All are cosmetic, probably from the PMC manuscript conversion; refs 2, 12, 24 and 25 show similar stray semicolons or year placement.
Second check: none (judge only)