{"id":"486fa381-5f9b-4353-82ab-e9f978e83765","arxiv_id":"2608.03914","paper_version":1,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"The IAR campaign found one FRB candidate with DM 243 pc cm^-3 and S/N 8.2, backed by successful recovery of archival and injected bursts.","lead":"Astronomers ran the first fast radio burst (FRB) search at Argentina's IAR 30-meter radio telescope, observing galaxy superclusters for 212 hours and finding one candidate burst, FRB 20251018. The result is notable because it would be the first FRB detected from South America and shows that a modest single-dish telescope can run standard FRB search pipelines.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Candidate FRB 20251018 is accepted without a measured pipeline false-positive rate, while comparable or stronger events in Table A.1 are dismissed as marginal; the capability claim therefore rests on an unconfirmed single event.","rationale":"The paper is a careful engineering and campaign report: the pipeline successfully recovers all seven archival Parkes FRBs and all six injected synthetic bursts (Appendix B), and the candidate has a plausible DM and passes a channel-zapping robustness test reported in an ATel. These are real, checkable achievements, and the paper is appropriately cautious in several places, explicitly acknowledging the absence of a repeat burst and the existence of marginal candidates. However, the headline capability claim goes beyond 'the pipeline can find injected/archival signals' to 'the IAR antennas are capable of detecting FRBs' in real data, and that step is supported only by a single 8.2 sigma candidate with no independent confirmation. The most direct threat is not the lack of a second antenna per se, but the absence of any measurement of the pipeline's false-positive rate on real noise/RFI. Table A.1 shows that candidates with S/N and FETCH p equal to or better than FRB 20251018 occur several times in 212 h and are dismissed as marginal, so the threshold-plus-classifier combination evidently does not by itself separate astrophysical bursts from RFI. The selection of FRB 20251018 as real therefore depends on human judgement and an ATel-reported test whose statistical power is not quantified. A scrambled-time control sample run through the full pipeline would directly measure how often a purely instrumental event would be promoted to candidate by the same criteria. If that rate is negligible, the reader's condition is satisfied and the verdict can be upgraded; if not, the claim should be explicitly limited to pipeline sensitivity. I agree with the reader's identification of the candidate's genuineness as the weakest assumption, and CONDITIONAL remains the appropriate verdict pending this check.","tokens_in":14315,"tokens_out":7973,"duration_ms":76149,"concrete_test":"Create a null-hypothesis control dataset by reversing the time axis of each of the 212 h of IAR filterbank observations (or by permuting time samples within each frequency channel), which destroys any dispersed astrophysical signal with positive dispersion slope while preserving noise and RFI statistics. Run the exact production pipeline—same static channel mask, rfifind flagging, DDplan/prepsubband grid (DM 100–500, step 1 pc cm^-3), single_pulse_search at 8 sigma with the same boxcar set, FETCH model A threshold p>0.5, and the same visual-inspection criteria—on this control set, and count how many candidates reach S/N>=8.2 with FETCH p>=0.99 and survive visual inspection.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim that the IAR antennas are capable of detecting FRBs—and the supporting 'first FRB from South America'—rests on FRB 20251018 (S/N=8.2, DM=243, FETCH p=0.99; Sect. 5). The paper does not quantify the false-positive rate of the full PRESTO+FETCH+visual-inspection pipeline on real IAR noise/RFI data. This matters because Table A.1 lists five additional candidates with S/N 8.40–12.47 and FETCH p up to 0.997, including one (A4013, 2025-10-15) with both higher S/N (9.23) and higher p (0.997) than FRB 20251018, which are nonetheless classified as marginal on the basis of diagnostic plots. Thus high S/N and high FETCH p are not sufficient to establish astrophysical origin in this dataset; the final decision for FRB 20251018 rests on visual inspection and a channel-zapping test described only in an ATel, not on a statistical demonstration that such events are rare in the absence of a real burst. With S/N only 0.2 sigma above the search threshold and no second-antenna coincidence, repeat burst, or external confirmation, the event could be the tail of the same RFI/noise population that produced the marginal candidates. The paper itself concedes no repeat has been seen and proposes dual-antenna observations as a future discriminator. Without a false-positive-rate estimate, the capability demonstration is not yet distinguished from a pipeline that recovers injected signals but also produces occasional convincing false positives.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper reports the first blind fast radio burst (FRB) search campaign at the Argentine Institute of Radio Astronomy (IAR), using the A2 30 m antenna with a ROACH backend over 212 hours of observations toward the Ophiuchus, Shapley, Sculptor, and Phoenix supercluster fields. The search uses PRESTO for dedispersion and single-pulse detection in the DM range 100–500 pc cm−3, followed by FETCH classification and visual inspection. The pipeline is validated on seven Parkes archival FRBs and six synthetic injections, including a blind test. The campaign yields one candidate, FRB 20251018 (S/N=8.2, DM=243 pc cm−3, FETCH p=0.99), in the direction of A2870, which the authors argue would be the first FRB detected from South America. Five marginal candidates are also listed. The paper concludes that the IAR antennas are capable of detecting FRBs and derives an all-sky rate estimate consistent with literature values.","tokens_in":14601,"tokens_out":5365,"duration_ms":49889,"significance":"The paper's principal strength is its validation strategy: recovering all seven Parkes archival FRBs and all six injected bursts, including a blind injection analyzed by three independent team members, is a meaningful demonstration that the PRESTO+FETCH pipeline can find dispersed transients in IAR data. The authors are also refreshingly transparent about the marginality of their candidate, the absence of a repeat burst, and the need for future dual-antenna confirmation. If FRB 20251018 is genuine, the result would show that a 30 m single dish with a modest 400 MHz backend can contribute to FRB science and would open a new southern-hemisphere monitoring capability. However, the central claim of a 'first FRB from South America' and the implied capability demonstration rest on a single candidate whose signal-to-noise ratio is only 0.2 above the search threshold and for which no false-positive rate is measured. The significance of the paper is therefore conditional on the reality of FRB 20251018; the validation tests alone establish pipeline sensitivity, but not the astrophysical nature of the one reported event.","major_comments":[{"comment":"The capability claim and the 'first FRB from South America' headline rest on FRB 20251018 (S/N=8.2, DM=243 pc cm−3, FETCH p=0.99; Section 5), but the paper does not provide a measured false-positive rate for the full PRESTO+FETCH+visual-inspection pipeline on real IAR noise/RFI data. This issue is load-bearing because Table A.1 lists five other candidates with S/N 8.40–12.47 and FETCH p up to 0.997 that are rejected as marginal on the basis of diagnostic plots; hence high S/N and high FETCH p do not by themselves establish astrophysical origin in this dataset. Since FRB 20251018 sits only 0.2σ above the search threshold and has no second-antenna coincidence, repeat burst, or external confirmation, the paper should quantify how often the pipeline produces a candidate at least as convincing as this one from noise/RFI alone (for example, by running the identical pipeline on time-reversed or scrambled noise-only observations from the same fields). Without such a number, the single detection is not statistically distinguished from the false-positive tail that produced the Table A.1 candidates.","section":"§5 and Table A.1"},{"comment":"The astrophysical nature of FRB 20251018 is currently supported only by visual inspection and by a hierarchical channel-zapping test described solely in an Astronomer's Telegram (Prajapati et al. 2026), not in this manuscript. The paper itself states that no repeat burst has been identified and that dual-antenna observations are needed as a 'decisive discriminator' against local interference. I ask the authors either to include the full channel-zapping results and diagnostic plots for FRB 20251018 in the paper, or to explicitly relabel the event as a candidate and to rest the capability demonstration on the injection/archival validation in Appendix B, which is strong and independent of this event. As written, the conclusion that 'the IAR antennas are capable of detecting FRBs' conflates pipeline recovery of injected signals with the detection of a real astrophysical burst.","section":"§5, Appendix A, and ATel Prajapati et al. (2026)"}],"minor_comments":[{"comment":"The column header 'Datet start' appears to be a typo; it should read 'Date of t_start' or a similarly clear label indicating that the date belongs to the start of the observation.","section":"Table A.1"},{"comment":"The flux-density estimate quotes 3.0±0.5 Jy and a fluence of 27±5 Jy ms using W_eq≈9 ms, whereas the ATel reports 3.9±0.9 Jy using the FWHM of the profile; the paper should state explicitly which width definition is used in each place and clarify that the difference reflects that choice rather than an inconsistency.","section":"§5"},{"comment":"The sentence about the Parkes validation is ambiguous: after saying the archival set comprises seven FRBs, the text says 'In particular, we focused on the detection of FRB 110703, and we also injected a synthetic signal with FRB-faker that was successfully recovered' — it is unclear whether the injection was into the Parkes data or into a separate observation; please clarify.","section":"Appendix B"},{"comment":"The rough rate estimate that 'a detection is likely after ~1000 h' is presented without an explicit derivation of the beam solid-angle factor; giving the assumed all-sky rate and showing ΔΩ = πθ_FWHM^2/4 with the adopted 30′ beam would make the estimate more reproducible.","section":"§4"},{"comment":"The statement that data are available 'upon reasonable request' is weaker than current FAIR expectations for a survey paper; making candidate cutouts, the static RFI mask, and pipeline configuration files publicly available would strengthen reproducibility.","section":"Data availability"}],"recommendation":"major_revision","confidential_remarks":"The headline 'first FRB from South America' is likely to attract attention beyond the strength of the current evidence. The central risk is that the single candidate has S/N only 0.2σ above threshold, with no measured false-positive rate, while comparable or stronger Table A.1 events are dismissed by visual inspection. The validation tests are genuinely strong, and the authors' transparency is a positive signal; I therefore view this as fixable by additional analysis or by carefully reframing the claims, not as grounds for rejection. The editor may wish to ensure that the published wording does not overstate confidence in FRB 20251018 before independent confirmation or a false-positive-rate estimate is available."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"First, what's new: this is the first blind FRB search using the IAR 30-m ROACH backend, with 212 h on southern supercluster fields, and a pipeline validated on seven Parkes archival FRBs and six injected bursts, including a blind test—all recovered. That part is solid, and the authors are honest about the system parameters, the RFI masking, and the Poisson-dominated rate estimate.\n\nThe soft spot is exactly what the stress-test says: the capability claim and the 'first from South America' tag hang on one candidate, FRB 20251018, S/N=8.2, DM=243, FETCH p=0.99—only 0.2 sigma above the 8 sigma threshold. The paper does not measure the false-positive rate of the PRESTO+FETCH+visual inspection pipeline on real IAR data. That matters because Table A.1 lists five marginal candidates, including one with S/N=9.23 and p=0.997 that is dismissed by visual inspection. So S/N and p are not sufficient; the final cut is a subjective eyeballing step, and the channel-zapping evidence is only referenced to an ATel, not shown. With no second antenna, no repeat, and no external confirmation, FRB 20251018 could be the tail of the same distribution that produced the marginal candidates. The paper itself acknowledges the lack of a repeat.\n\nTo their credit, the authors don't oversell: they say 'would be' the first, they list the marginal candidates, and they propose dual-antenna coincidence as the decisive test. The campaign description and validation are genuinely useful for anyone planning FRB searches with small single dishes.\n\nBottom line: the paper deserves a serious referee. It should be sent to review, not desk-rejected, but the claims need to be rebalanced: the candidate should be marked unconfirmed until verified, and the authors should add a false-positive estimate from noise/RFI injections or off-pulse trials. With that revision it would be a solid facility paper.","headline":"A careful first-search report from a new southern single-dish facility whose 'first FRB from South America' rests on a single, unconfirmed S/N=8.2 candidate.","tokens_in":15145,"tokens_out":2426,"would_cite":false,"duration_ms":21774,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"The paper claims that a 212-hour campaign with the Argentine Institute of Radio Astronomy's 30-meter dishes detected a credible fast radio burst candidate, FRB 20251018, which would be the first FRB from South America and demonstrates the…","keywords":["fast radio bursts","single-pulse search","southern sky surveys","superclusters","radio astronomy instrumentation","dispersion measure","machine learning classification","transient searches"],"falsifier":"Repoint both IAR antennas at A2870 for a sustained campaign and search for a burst appearing simultaneously in both receivers; also re-run the search on the 18 October 2025 data with the frequency mask varied and on an off-source control dataset. If no second burst ever appears, no dual-antenna coincidence is recorded, and the candidate disappears under slightly different RFI flagging, then the event is best explained as noise or interference rather than an astrophysical FRB.","tokens_in":14143,"feed_emoji":"📡","tokens_out":10966,"duration_ms":86493,"temperature":0.7,"pith_summary":"This paper reports the first blind search for fast radio bursts (FRBs) carried out with the two 30-meter antennas of the Argentine Institute of Radio Astronomy, using 212 net hours of observations toward southern-sky superclusters between December 2024 and March 2026. The campaign identified one candidate, FRB 20251018, near the galaxy cluster A2870 in the Phoenix supercluster, with a dispersion measure of $243\\,\\mathrm{pc\\,cm^{-3}}$ and a signal-to-noise ratio of 8.2; the authors argue that this would be the first FRB detected from South America. Because the pipeline recovered all seven archival Parkes FRBs and all six synthetic injected bursts, the paper concludes that the IAR dishes are capable of FRB science and can contribute to southern-sky monitoring and multimessenger follow-up.","feed_headline":"Argentina's 30-meter dishes catch first South American FRB candidate","feed_subtitle":"A single 8.2-sigma burst near A2870 would be the first FRB caught from South America.","key_machinery":"The load-bearing mechanism is the single-pulse search chain built around the ROACH backend: a 400 MHz band at 1400 MHz digitized at 41–82 μs, dedispersed over a trial-DM grid from 100 to 500 pc cm$^{-3}$, searched for $8\\sigma$ single pulses up to about 29 ms width, and filtered by a deep-learning classifier that assigns each candidate a probability of being an astrophysical burst. The chain was validated by recovering seven known FRBs in archival Parkes data and six synthetic bursts injected into IAR observations, including a blind test. The DM uncertainty is derived from the width of the signal-to-noise versus trial-DM response, and a hierarchical channel-zapping test shows the candidate survives masking down to the cleanest 170 MHz of band.","core_discovery":"The paper's central claim is that the IAR 30 m antennas, equipped with ROACH digital backends, can detect fast radio bursts. The evidence is one candidate, FRB 20251018, observed on 18 October 2025 in the direction of the Phoenix-supercluster galaxy cluster A2870, with DM = $243\\pm15\\,\\mathrm{pc\\,cm^{-3}}$, a width of about 6 ms, signal-to-noise ratio 8.20, and a machine-learning classification probability $p=0.99$. The burst's DM exceeds the expected Milky Way contribution of roughly 20–31 pc cm$^{-3}$ by about 170–220 pc cm$^{-3}$, implying an extragalactic origin at redshift $z\\lesssim0.2$, consistent with A2870 itself or a background source. The paper also lists five more marginal candidates and notes that no repeat burst from the candidate position has been seen in continued monitoring. The authors state that, to their knowledge, this would be the first FRB detected from South America.","pith_inferences":["If the candidate is ultimately confirmed by a second receiver or a repeat burst, its large host-frame DM excess would suggest that some FRBs arise in dense cluster environments, a property targeted cluster surveys could quantify.","The capability claim currently rests on a single near-threshold event; the paper's own statement that no repeat or coincident detection exists means the 'first South American FRB' status remains provisional rather than established.","The demonstrated recovery of injected bursts with signal-to-noise ratios as low as 10 implies the IAR system could serve as a template for low-cost single-dish FRB searches at other southern observatories.","A natural extension the paper does not carry out is a systematic cross-match of IAR candidates with published FRB catalogs to look for repeaters or multi-telescope coincident events."],"forward_implications":["If FRB 20251018 is real, the IAR 30 m dishes can join FRB science, adding a flexible southern-hemisphere single-dish station.","Continued monitoring of A2870 and A4013 can test whether the candidate repeats, which would confirm an astrophysical origin and enable repeat-burst studies.","Dual-antenna (A1+A2) coincident observations will provide a decisive test against local interference for near-threshold candidates.","The implied all-sky rate, about $2\\times10^{4}$ sky$^{-1}$ day$^{-1}$ above the survey sensitivity, is consistent with published rates and suggests additional detections with longer campaigns.","Cross-matching IAR candidates with gravitational-wave events and other transients can constrain FRB progenitor channels in the southern sky."],"supporting_citations":[{"why":"Characterizes the IAR front-end, RFI environment, and antenna gain/system temperature used for the flux-density estimate.","marker":"Gancio et al. (2020)"},{"why":"Original Astronomer's Telegram reporting FRB 20251018; the paper compares its flux estimate with this discovery report.","marker":"Prajapati et al. (2026)"},{"why":"Provides the archival Parkes dataset containing seven known FRBs used to validate the search pipeline.","marker":"Keane & Petroff (2015)"},{"why":"Presents the FETCH deep-learning classifier that assigns astrophysical probabilities to candidates and drives down-selection.","marker":"Agarwal et al. (2020)"},{"why":"Compiled all-sky FRB rate estimates used for the expected-rate calculation and comparison with the campaign's implied rate.","marker":"Petroff et al. (2019)"},{"why":"NE2001 Galactic electron-density model used to estimate the Milky Way DM contribution toward the candidate.","marker":"Cordes & Lazio (2002)"},{"why":"YMW16 model providing an alternative Galactic DM estimate used for the extragalactic DM excess.","marker":"Yao et al. (2017)"},{"why":"Supplies the DM–redshift relation used to convert the candidate's DM excess into a redshift upper limit.","marker":"Macquart et al. (2020)"}],"fun_headline_variants":["Argentina's IAR dishes spot possible first South American FRB","30-m antenna at IAR catches FRB candidate from Phoenix cluster","First FRB search at Argentine observatory finds single burst","Candidate FRB from A2870 captured by IAR's 30-meter dish","South America's first FRB? Argentine telescope finds candidate"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that FRB 20251018 is a genuine astrophysical burst rather than a statistical fluctuation or radio-frequency interference; with a signal-to-noise ratio of 8.2 just above the $8\\sigma$ threshold, no independent confirmation from a second antenna or another facility, and no repeat burst, the single event is the most fragile premise on which the 'first FRB from South America' and the capability claim rest.","fun_headline_variants_meta":{"raw":{"variants":["Argentina's IAR dishes spot possible first South American FRB","30-m antenna at IAR catches FRB candidate from Phoenix cluster","First FRB search at Argentine observatory finds single burst","Candidate FRB from A2870 captured by IAR's 30-meter dish","South America's first FRB? Argentine telescope finds candidate"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000243,"raw_usage":{"total_tokens":1621,"prompt_tokens":1132,"completion_tokens":489,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":748,"completion_tokens_details":{"reasoning_tokens":400}},"tokens_in":748,"tokens_out":489,"duration_ms":4807,"temperature":1.0,"reasoning_tokens":400,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T14:44:18.093707+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Repoint both IAR antennas at A2870 for a sustained campaign and search for a burst appearing simultaneously in both receivers; also re-run the search on the 18 October 2025 data with the frequency mask varied and on an off-source control dataset. If no second burst ever appears, no dual-antenna coincidence is recorded, and the candidate disappears under slightly different RFI flagging, then the event is best explained as noise or interference rather than an astrophysical FRB.","supporting_citations":[],"review_version":2}