First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole

• p. 1 Abstract

  ratio 10:1

• p. 8 Table 1, Crescent contrast

  >10:1

• p. 9 Section 9

  contrast of >10:1

Judge's note: Page 1 image shows the abstract with the ≳ sign (lost in the text layer); the page 8 image shows Table 1 with ">10:1" and the page 9 image shows "contrast of >10:1". The two relations differ, but this is loose usage for one lower limit and either form could be intended.

Second check: none (judge only)

• p. 6 Section 6, second paragraph, definition of φ

  MRg

• p. 1 Section 1, definition

  is the characteristic lengthscale of a black

Judge's note: Page 6 image, second paragraph, shows capital R with subscript g in the definition of φ. Page 1 defines lower-case r_g, which is also used on pages 2 and 6. The notation is inconsistent, though the meaning is clear. The reviewer's further point about a missing factor of c is a units convention and is not confirmed as a defect.

Second check: none (judge only)

• p. 2 Section 1, left column, second paragraph

  very long baseline interferometery (VLBI) experiments

• p. 2 Introduction, para 2

  very long baseline interferometery (VLBI)

• p. 2 Section 1, paragraph 2

  interferometery

Judge's note: Visible on the page 2 image, left column, second paragraph. The abstract on page 1 spells it "interferometry".

Second check: none (judge only)

• p. 2 Section 1, last paragraph (top of right column)

  EHT Collaoration et al.

• p. 2

  EHT Collaoration et al. 2019b, hereafter Paper III

Judge's note: Visible on the page 2 image, top of the right column. The other four companion-paper citations in the same sentence spell "Collaboration" correctly.

Second check: none (judge only)

• p. 2 Section 2, last sentence

  21.3

Judge's note: Page 2 image, end of Section 2, shows 37.6 (+6.2, −3.5) μas and 21.3 (+5, −1.7) μas. The inconsistent precision is real. The reviewer's value of +5.5 is not established: scaling the mass bounds linearly gives about +5.4, but the same scaling does not reproduce the other printed uncertainties either (it gives +6.7 where +6.2 is printed), so the uncertainties were evidently not obtained by simple scaling and the omitted digit cannot be recovered from the paper.

Second check: none (judge only)

• p. 6 Section 6, left column, last paragraph

  Te ≃ Ti/Rhigh

• p. 6 Section 6, same paragraph

  Te ≃ Ti) regions

• p. 6 Section 6, same paragraph, definition

  nonrelativistic ions with temperature Ti and

• p. 6 Section 6, paragraph beginning 'Because the photons at 1.3 mm'

  Te ; Ti/Rhigh

Judge's note: The crop of page 6 shows T_i and T_e with lowered subscripts in the defining sentence, and then "Te" and "Ti" with the e and i on the baseline in both relations. Not an extraction artefact.

Second check: none (judge only)

• p. 8 Section 7, paragraph 'Combining results from all methods'

  4:3; this corresponds to a

• p. 8 Section 8, 'Fourth'

  ratio 4:3; similarly

• p. 8 Table 1, Axial ratio

  <4:3

Judge's note: Page 8 image shows the ≲ sign in both text passages (lost in the text layer) and a plain < in the Table 1 row "Axial ratio". Loose usage for one limit; either form could be intended.

Second check: none (judge only)

• p. 14 References, Palumbo et al. 2019

  Palumbo, F., Doeleman, S., Johnson, M., Bouman, K., & Chael, A. 2019

• p. 15 Author list

  Daniel C. M. Palumbo

• p. 14 Reference list

  Palumbo, F., Doeleman, S., Johnson, M., Bouman, K., & Chael, A. 2019, ApJ,

• p. 9 Section 9, space-based interferometry citations

  Palumbo et al. 2019; F. Roelofs et al. 2019b

Only the authors can say what is right here.

Judge's note: Rests on outside knowledge: that the first author of this submitted paper is Daniel Palumbo. The page image shows "Palumbo, F." in the reference; the author list on p. 15 has only "Daniel C. M. Palumbo" (affiliations 4, 11), and the reference's co-authors are all collaboration members. The text on p. 9 cites "Palumbo et al. 2019; F. Roelofs et al. 2019b", so the initial may have been carried over from Roelofs. The work is unpublished and not in the files, so only the authors can confirm.

Second check: none (judge only)

• p. 10 Acknowledgments, NSF grant list

  OPP-1248097

• p. 11 Acknowledgments, SPT paragraph

  grant PLR-1248097

Judge's note: Both readings checked on the page 10 image and the page 11 crop. The seven-digit number is identical and the prefixes differ. Which prefix is right cannot be settled from the files; both may have been in use for the same programme.

Second check: none (judge only)

• p. 10 Acknowledgments, left column

  the National Institute of

• p. 10 Acknowledgments, ALMA paragraph, right column

  National Institutes of Natural

Only the authors can say what is right here.

Judge's note: Rests on outside knowledge: that the organisation's official name is the plural "National Institutes of Natural Sciences". The inconsistency itself is in the files: the page 10 image shows the singular in the left column and the plural in the right column, both for the Japanese body.

Second check: none (judge only)

• p. 10 Acknowledgments, JCMT statement, right column

  Technologies Facility Council (UK)

Only the authors can say what is right here.

Judge's note: Rests on outside knowledge: the UK funding body's name is "Science and Technology Facilities Council". The page image shows "Science and Technologies Facility Council (UK)" exactly as quoted. The paper does not name the council anywhere else, so the correct form cannot be checked from the files.

Second check: none (judge only)

• p. 10 Acknowledgments, LMT statement, right column

  Instituto Nacional de Astrófisica, Óptica, y

• p. 16 Affiliation 52

  Instituto Nacional de Astrofísica, Óptica y Electrónica

Judge's note: The crop of p. 10 shows the accent on the o ("Astrófisica"). Affiliation 52 on p. 16 and affiliation 105 on p. 17 both print "Instituto Nacional de Astrofísica, Óptica y Electrónica" with the accent on the i, as does "Instituto de Astrofísica de Andalucía" in affiliation 5. The acknowledgment is the odd one out within the paper (it also adds a comma before "y").

Second check: none (judge only)

• p. 11 Acknowledgments, SPT paragraph (twice)

  Kavli Institute of

• p. 16 Affiliation 23

  Kavli Institute for Cosmological Physics, University of Chicago

Judge's note: The p. 11 crop shows "Kavli Institute of Cosmological Physics" twice in the SPT paragraph. Affiliation 23 on p. 16 has "Kavli Institute for Cosmological Physics". Same institute, two forms within the paper; the affiliation list (the institute's own address line) uses "for".

Second check: none (judge only)

• p. 13 References, Chan et al. 2015

  Narayan, R., & Saowski, A. 2015

• p. 14 References, Sądowski et al. 2014

  Narayan, R., McKinney, J. C., & Tchekhovskoy, A. 2014

• p. 13 References, Chan et al. 2015

  Saowski, A. 2015

• p. 13

  Narayan, R., & Saowski, A. 2015, ApJ, 799, 1

Judge's note: The page image shows "Saowski, A." in the Chan et al. 2015 entry, so this is in print and not a text-layer loss. On p. 14 the same list prints "Sądowski, A." in the Narayan et al. 2012 and Sądowski et al. 2014 entries, each with Narayan as co-author.

Second check: none (judge only)

• p. 13 References, Doeleman et al. 2009a

  Doeleman, S., Agol, E., Dacker, D., et al. 2009a

• p. 13 References, Bower et al. 2003

  Falcke, H., & Backer, D. C. 2003

Only the authors can say what is right here.

Judge's note: Rests on outside knowledge: the third author of the Astro2010 white paper is D. Backer. The page image shows "Dacker, D." as quoted. The same reference list has "Backer, D. C." in the Bower et al. 2003 entry, and the author sits in alphabetical position after Agol, which supports the reading, but the white paper's author list is not in the files.

Second check: none (judge only)

• p. 14 References, Thompson et al. 2017

  (3rd ed.; Berlin: Spinger)

• p. 14 References, Thompson, Moran & Swenson 2017

  Berlin: Spinger

• p. 14

  and Synthesis in Radio Astronomy (3rd ed.; Berlin: Spinger)

Judge's note: The page image shows "Berlin: Spinger" in the Thompson, Moran & Swenson 2017 entry. Plain misspelling.

Second check: none (judge only)

• p. 15 Author list, first block

  Tomoaki Oyama33

• p. 15 Author list, second block

  Tomoaki Oyama133

• p. 16 Affiliation 33

  2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan

• p. 17 Affiliation 133

  Ohshu, Iwate 023-0861, Japan

Only the authors can say what is right here.

Judge's note: Both entries are visible in the page image of the author list, the first in the alphabetical main block and the second in the later block that runs to "and Lucy Ziurys". Affiliation 33 (p. 16) reads "Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan"; affiliation 133 (p. 17) reads "Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, Ohshu, Iwate 023-0861, Japan". Same name and same observatory listed twice; nothing in the paper says these are two people. Only the authors can say whether it is a duplicate, hence a query. No effect on the science.

Second check: none (judge only)

• p. 17 Affiliation 108

  MIT Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA

• p. 15 Affiliation 2

  Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA

Judge's note: Seen in the page images: affiliation 2 on p. 15 and affiliation 108 on p. 17 are the same institution at the same address; 52 (p. 16) and 105 (p. 17) are both the Instituto Nacional de Astrofísica, Óptica y Electrónica with different address lines; 85 and 106 (p. 17) are both the Consejo Nacional de Ciencia y Tecnología at Av. Insurgentes Sur 1582. Duplicate affiliation numbers for one institution, apparently from joining two author lists. Harmless to readers; noted as a consistency point.

Second check: none (judge only)

• p. 16 Affiliation 41

  32-D476, 77 Massachussetts Ave.

• p. 16 Affiliation 41

  77 Massachussetts Ave.

• p. 16

  32-D476, 77 Massachussetts Ave., Cambridge, MA 02142, USA

Judge's note: The page image shows "Massachussetts Ave." on the second line of affiliation 41, directly under "Massachusetts Institute of Technology" spelled correctly on the first line.

Second check: none (judge only)

• p. 16 Affiliation 60

  Kaosiung City 80424

Only the authors can say what is right here.

Judge's note: Rests on outside knowledge: the city's usual romanised name is Kaohsiung. The page image shows "Kaosiung City 80424" as quoted. The city is not named anywhere else in the paper, so there is no internal comparison.

Second check: none (judge only)

• p. 17 Affiliation 94

  Postbus 2300, 9513 RA Leiden

• p. 16 Affiliation 47 (also 13)

  P.O. Box 9513, 2300 RA Leiden

Judge's note: The page images show affiliation 94 with "Postbus 2300, 9513 RA Leiden" and affiliation 47 (Leiden Observatory—Allegro, Leiden University) with "P.O. Box 9513, 2300 RA Leiden"; affiliation 13 (NOVA) in the text also has "PO Box 9513, 2300 RA Leiden". Two entries agree and one has the numbers the other way round, for the same institution. Which form is the true address is outside the files, but the inconsistency is in print and the two-to-one agreement points to affiliation 94.

Second check: none (judge only)

• p. 17 Affiliation 109

  501 Campbell, Berkeley, CA 94720

• p. 17 Affiliation 142

  601 Campbell, Berkeley, CA 94720

Judge's note: Both lines are as quoted in the p. 17 image. The two entries are not identical units (142 adds "Radio Astronomy Laboratory"), so 501 and 601 may be two room numbers in the same building and both could be right. The files cannot settle which, so this is recorded only as a consistency point for the authors to check.

Second check: none (judge only)