A Bright Millisecond Radio Burst of Extragalactic Origin
Science, 2007 · paper · Astronomy
Reports a bright radio burst lasting under 5 milliseconds, found in archival Parkes pulsar-survey data near the Small Magellanic Cloud. Its properties argue against a Galactic origin; it did not repeat, suggesting a singular, likely extragalactic event.
Checked: PDF from arxiv.org, fetched 4 Oct 2026. Page numbers are those of that PDF.
6 findings
Substance Page 4: "Including the original detection, there were a total of 27 beams ... These observations, which total 50 hr, were carried out between 2001 June 19 and July 24", but the detection is dated "2001 August 24" on page 2 and in the Figure 2 caption, outside that range.
- p. 4 paragraph 'We have extensively searched...'
carried out between 2001 June 19 and July 24
- p. 2 last paragraph
The burst was detected in data taken on 2001 August 24
- p. 12 Figure 2 caption
collected on 2001 August 24
- p. 4 second paragraph
carried out between 2001 June 19 and July 24 and show no significant bursts
Only the authors can say what is right here.
Judge's note: Viewed pages 2, 4 and 12. The detection date 2001 August 24 is printed twice (page 2 text and Figure 2 caption). Page 4 says the 27 beams include the original detection and that these observations ran from June 19 to July 24, which ends a month before the detection. I searched the text for another statement of the survey dates or a qualification that the range covers only the other beams and found none. One of the dates is wrong (the shared day 24 suggests a month slip), but only the authors can say which.
Second check: another model agreed
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Substance Page 13: "For truly unbiased single-bit data, the expected sum is 48 (i.e. half zeros and half ones) with a standard deviation of √48 = 6.9": the sum of 96 unbiased one-bit samples has variance 96 × 0.5 × 0.5 = 24, standard deviation √24 ≈ 4.9.
- p. 13 Interference excision
with a standard deviation of √48 = 6.9
- p. 13 Interference excision
standard deviation of √48 = 6.9
- p. 13 Interference excision
48 = 6.9
- p. 13 Methods, Interference excision
the expected sum is 48 (i.e. half zeros and half ones) with a standard deviation of
Only the authors can say what is right here.
Judge's note: Viewed page 13; the image prints √48 = 6.9. The text itself fixes the model: 96 channels, each 0 or 1 with equal probability, mean 48. For that sum the variance is n·p·(1−p) = 24, so the standard deviation is about 4.9; √48 takes the mean as the variance. The printed arithmetic √48 = 6.9 is itself right (6.9 squared is 47.6). No other definition of the sum (polarisations, ±1 coding) is given anywhere in the methods. The three-standard-deviation clipping threshold in the next sentence depends on this value; whether the software used 6.9 or the text misstates it is for the authors, hence a query.
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Reference or label Page 7: "we estimate that a 10^33-Jy radio burst would be detectable out to z ∼ 0.3": the quantity is the burst energy, given on page 6 as "∼ 10^33 W5 D500^2 J"; the unit should be J, not Jy.
- p. 7 first paragraph, line 3
we estimate that a 1033-Jy radio burst would be
- p. 6 paragraph 'What is the nature of the burst source?'
∼1033W5D2
- p. 7 rate paragraph, para 1
a 1033-Jy radio burst would be
- p. 7 rate paragraph
a 1033-Jy radio burst
Judge's note: Viewed pages 6 and 7. The page 7 image prints 10^33 with a superscript and the unit Jy (the text layer's "1033-Jy" is only the lost superscript). Page 6 gives the energy released as about 10^33 J, the next sentence on page 7 says "bursts of this energy", and the burst's flux density is 30 Jy throughout. The value is right and the unit is wrong, so S2.
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Wording Fig. S2 caption: "S/N of 23 and DM of 360 cm−3 pc (the closest trial DM to the true value determined in the paper" — the true DM is 375±1 cm−3 pc, the plot header prints "Peak DM = 359.1", and the S/N-versus-DM panel shows detections at many trial DMs between about 310 and 420, so 360 is the trial with the highest S/N, not the closest trial to 375; it also sits oddly with "183 time series ... DM range 0–500" and a step "always less than one time sample".
- p. 18 Figure S2 caption
DM of 360 cm−3 pc (the closest trial DM to the true value
- p. 14 Time series generation
The DM step size was chosen such that the delay introduced at a slightly incorrect trial DM was always less than one time sample
- p. 18 Figure S2 plot header
Peak DM = 359.1 cm−3 pc
- p. 18 Figure S2 caption
S/N of 23 and DM of 360 cm−3 pc
Only the authors can say what is right here.
Judge's note: Viewed page 18 (re-rendered at 3x) and page 14. The S/N-vs-DM panel has a dense cloud of points from roughly DM 310 to 420 peaking near 365-380, so trial DMs much nearer 375 than 360 exist; the caption's parenthesis is contradicted by its own figure. 183 trials over 0-500 give a mean step of about 2.7, and a 15-unit offset corresponds to about 14 ms of sweep across the 1.2285-1.5165 GHz band (band edges from page 13), against the stated sub-sample criterion. The secondary point that 183 trials cannot keep the band-wide delay below 1 ms everywhere (2.7 units ≈ 2.6 ms) is real as arithmetic but the criterion is not defined precisely (spacing may be non-uniform, or refer to half a step), so it is folded in as a query. The S/N part of the cluster is not a defect: Fig. 1 says the digitizers saturated, 'indicating that its S/N ≫ 23', which treats the measured 23 as a lower limit and is consistent with Fig. S2.
Second check: another model agreed
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Wording Equation 2, "ΔSsys = βTsys / (G √(np Nadd tsamp Δf)) = Cσ": the symbol np is not defined; the definitions that follow cover β, Tsys, G, Nadd, tsamp, Δf and C only.
- p. 15 Equation (2) and the following definitions
where β = √π/2 is a factor accounting for losses due to 1-bit digitization
- p. 15 Eq. (2) and following definitions
where β = √π/2 is a factor accounting for losses due to 1-bit digitization, Tsys ≈ 30 K
Only the authors can say what is right here.
Judge's note: Viewed page 15. Equation 2 has np under the square root. The sentence after it defines every other symbol and gives values, but not np, and np does not appear elsewhere in the text. It is presumably the number of polarisations, but the value needed to evaluate C is not given.
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Wording Eq. (2) has sqrt(n_p N_add t_samp Δf) with "Nadd is the number of times the time samples have been added in pairs"; under that definition the integration time after N_add pairwise additions is 2^N_add × t_samp (the text's own 10 additions give 1.024 s), and N_add = 0 for the unsmoothed 1-ms series would make the expression diverge.
- p. 15 definitions after Equation (2)
Nadd is the number of times the time samples have been added in pairs
- p. 15 Single-pulse detection
This process is repeated a total of 10 times until a time resolution of 1.024 s has been reached
Only the authors can say what is right here.
Judge's note: Read page 15. The definition is printed as quoted, and the same page says pairwise addition is "repeated a total of 10 times until a time resolution of 1.024 s has been reached", i.e. 2^10 × 1 ms. The radiometer equation needs the number of samples summed (2^N_add), not the number of pairwise additions. Either the definition or the equation is loosely written; nothing elsewhere in the paper redefines N_add. Notation defect, not a wrong reported result.
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10 minor (typos and the like; most checked by the judge only)
Wording Abstract: "No further bursts are seen in 90-hr of additional observations"; the 90 hr is 50 hr of survey data plus 40 hr of follow-up, and the 50 hr is introduced with "Including the original detection, there were a total of 27 beams", so part of the 90 hr is the discovery observation itself.
- p. 1 abstract
No further bursts are seen in 90-hr of additional observations
- p. 4 paragraph 'We have extensively searched...'
Including the original detection, there were a total of 27 beams
Judge's note: Viewed pages 1 and 4. 50 + 40 = 90 matches the abstract. Page 4 says the 27 beams totalling 50 hr include the original detection (detected in three beams of one 2.3-hr pointing), so not all 90 hr is additional to the discovery. The rest of those beams' time is still time on source in which no second burst was seen, so this is a loose wording point only.
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Wording "interstellar scattering with a Kolmogorov power law (W ∝ f^−4, 11)": the exponent −4 is labelled Kolmogorov, and the measured W ∝ f^(−4.8±0.4) is called consistent with it (again on page 4: "a scattering relation consistent with the Kolmogorov power law").
- p. 3 second paragraph
interstellar scattering with a Kolmogorov power law (W ∝f −4
- p. 4 first paragraph
a scattering relation consistent with the Kolmogorov power law
- p. 3 first paragraph
pulse-width evolution due to interstellar scattering with a Kolmogorov power law (W ∝f −4,
- p. 12 Figure 2 caption
W = 4.6 ms (f/1.4 GHz)−4.8±0.4
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: that scatter broadening for a Kolmogorov turbulence spectrum scales as f^−4.4, while f^−4 is the square-law (Gaussian) result. The page 3 image prints W ∝ f^−4 with the name Kolmogorov, and the Figure 2 caption on page 12 prints −4.8±0.4. The measured index is 2 sigma from −4 and 1 sigma from −4.4. The paper gives no definition of its own, so this is a query on the exponent or the name; the consistency statement holds loosely either way.
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Wording Fig. S2 caption: "approximately 1650 s after the start of the observation", whereas the burst column in the lower panel sits at about 1730 s on the time axis.
- p. 18 Figure S2 caption
approximately 1650 s after the start of the observation
Judge's note: Re-rendered the figure at 3x and measured: the 1000 s and 2000 s ticks are at x≈269 and x≈424 px, the burst column at x≈382 px, giving about 1730 s. That is roughly 80 s later than the caption's figure. The caption says 'approximately' and the reading is by eye from the plot (uncertainty perhaps ±15 s), so this is a small consistency point; the plotted time might also be referenced differently (e.g. to a different frequency channel or DM), which only the authors can say.
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Typo "any radio signal of astrophysical origin should exhibit a quadratic shift in their arrival time": singular subject with plural pronoun ("its arrival time").
- p. 2 second paragraph
any radio signal of astrophysical origin should exhibit a quadratic shift in their arrival time
Judge's note: Read on the page 2 image; the sentence is printed as quoted. Number disagreement, cosmetic.
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Typo "18 known radio pulsars in the Magellanic clouds" (page 4) and "survey of the Magellanic clouds" (page 13) against "survey of the Magellanic Clouds" (page 2): inconsistent capitalisation of a proper name.
- p. 4 p. 4 pulsar DM discussion
18 known radio pulsars in the Magellanic clouds
- p. 2 p. 2 survey description
survey of the Magellanic Clouds
Judge's note: Read on the images of pages 2, 4 and 13. The lower-case form appears twice and the capitalised form once (plus "Small Magellanic Cloud" and "Large Magellanic Cloud" capitalised). Cosmetic.
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Typo "Although we have only a limited information on the flux density spectrum": stray article ("only limited information").
- p. 3 third paragraph
Although we have only a limited information on the flux density spectrum
- p. 3 flux density paragraph
we have only a limited information on the flux density spectrum
Judge's note: Read on the page 3 image; printed as quoted. Cosmetic grammar slip.
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Typo Page 5: "since a host Galaxy and local environment could both contribute" (capital G, against "putative host galaxy" on the same page) and "the non detection in the PGC" (unhyphenated, one sentence after "the non-detection of the burst").
- p. 5 third paragraph
since a host Galaxy and local environment could both contribute
- p. 5 second paragraph
the non detection in the PGC
- p. 5 same paragraph, earlier sentence
the non-detection of the burst in the beam south
Judge's note: Read on the page 5 image. Both slips are printed as quoted; the page uses "host galaxy" lower-case twice and reserves "Galaxy" for the Milky Way, and "non-detection" is hyphenated in the preceding sentence. Cosmetic.
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Typo Page 13 lists the processing sequence as "interference excision, time series generation, baseline removal, single-pulse detection and diagnostic plot production", but the third subsection is headed "Time series normalization".
- p. 13 Materials and methods, first paragraph
interference excision, time series generation, baseline removal, single-pulse detection and diag-
- p. 14 section heading
Time series normalization
Judge's note: Viewed pages 13, 14 and 15. The subsection headings are Interference excision, Time series generation, Time series normalization, Single-pulse detection and Diagnostic plotting. The third step carries a different name in the list; the section does describe subtracting the mean (baseline removal) and computing the standard deviation, so both names fit. Cosmetic naming inconsistency.
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Typo Eq. (2) contains n_p under the square root, but the definitions that follow ("is the antenna gain, Nadd is the ...") cover β, T_sys, G, N_add, t_samp, Δf and C and never define n_p.
- p. 15 Eq. (2) and following sentence
is the antenna gain, Nadd is the
Judge's note: Read page 15 and searched the text for n_p and 'polari': the symbol appears only in Eq. (2) and the number of polarizations is not stated anywhere in the article. The symbol is conventional (number of polarizations summed), so this is a missing definition, not a wrong value.
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Typo Fig. S2 caption: "highly dispersed isolated burst occuring approximately" — 'occuring' should be 'occurring'.
- p. 18 Figure S2 caption
isolated burst occuring approximately
- p. 18 Figure S2 caption
burst occuring approximately
- p. 18 Figure S2 caption
highly dispersed isolated burst occuring approximately
Judge's note: Visible on the page image and the caption crop; a plain misspelling, not an extraction artefact.
Second check: none (judge only)