arxiv: 2604.24249 · v1 · submitted 2026-04-27 · 🌌 astro-ph.HE · astro-ph.IM

Recognition: unknown

ECLAIRs: the SVOM high-energy transient trigger camera

O. Godet , J.-L. Atteia , S. Schanne , C. Lachaud , A. Goldwurm , F. Piron , Ph. Guillemot , C. Amoros

show 46 more authors

W. Bertoli L. Bouchet M. C. Charmeau F. Chteau B. Cordier N. Dagoneau F. Daly J.-P. Dezalay J. Galezzi A. Givaudan A. Gros M. Karakac K. Lacombe H. Leprovost S. Maestre K. Mercier H. Pasquier L. Perraud R. Pons D. Rambaud O. Simonella T. Tourrette H. Triou V. Waegebaert P. Bacon T. Barlyaeva N. Bellemont M.-G. Bernardini M. Brunet F. Cangemi C. Cavet A. Coleiro D. Corre F. Daigne A. Foisseau O. Gevin S. Guillot U. Jacob F. Lacreu S. Le Stum P. Maeght T. Maiolino A. Maolo G. Tcherniatinksy J. Wang H. Yang

Authors on Pith no claims yet

Pith reviewed 2026-05-08 02:03 UTC · model grok-4.3

classification 🌌 astro-ph.HE astro-ph.IM

keywords gamma-ray burstshigh-energy transientscoded mask camerain-flight performancetransient detectionspace instrumentation

0 comments

The pith

The ECLAIRs camera on the SVOM mission has been commissioned and reports in-flight performance for high-energy transient triggers up to March 2025.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper describes the ECLAIRs 4-150 keV coded mask camera as the primary instrument for autonomously triggering and localizing gamma-ray bursts and other transients. It covers the instrument subsystems, their characteristics, flight configuration, and measured performances after launch. The work then summarizes the science output achieved through March 31, 2025, showing the camera meets its operational goals for the mission.

Core claim

ECLAIRs functions as a 4-150 keV 2-D coded mask camera that triggers and localizes transients within its field of view; the flight model, built and operated under agency supervision, has delivered the reported in-flight performances and science results through March 31, 2025.

What carries the argument

The 2-D coded mask camera in the 4-150 keV band, which performs autonomous trigger and localization of high-energy transients.

If this is right

The camera enables real-time localization of transients for rapid multi-wavelength follow-up.
Measured performance metrics confirm the instrument can meet the mission's transient detection requirements.
Early science data through March 2025 provide a baseline for ongoing operations and data analysis.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Continued operation could yield a larger sample of localized transients than pre-launch models predicted if background levels remain stable.
The design choices validated here may inform the sensitivity trade-offs for similar coded-mask instruments on future missions.

Load-bearing premise

The reported in-flight measured performances and science results accurately represent the instrument's true capabilities without undisclosed calibration issues or selection effects in the data.

What would settle it

A well-characterized high-energy transient with known flux, spectrum, and position inside the field of view that either triggers the camera at the predicted rate or fails to trigger would directly test the performance claims.

Figures

Figures reproduced from arXiv: 2604.24249 by A. Coleiro, A. Foisseau, A. Givaudan, A. Goldwurm, A. Gros, A. Maolo, B. Cordier, C. Amoros, C. Cavet, C. Lachaud, D. Corre, D. Rambaud, F. Cangemi, F. Chteau, F. Daigne, F. Daly, F. Lacreu, F. Piron, G. Tcherniatinksy, H. Leprovost, H. Pasquier, H. Triou, H. Yang, J. Galezzi, J.-L. Atteia, J.-P. Dezalay, J. Wang, K. Lacombe, K. Mercier, L. Bouchet, L. Perraud, M. Brunet, M. C. Charmeau, M.-G. Bernardini, M. Karakac, N. Bellemont, N. Dagoneau, O. Gevin, O. Godet, O. Simonella, P. Bacon, Ph. Guillemot, P. Maeght, R. Pons, S. Guillot, S. Le Stum, S. Maestre, S. Schanne, T. Barlyaeva, T. Maiolino, T. Tourrette, U. Jacob, V. Waegebaert, W. Bertoli.

**Figure 9.** Figure 9: Angular distance from the ECL GRB positions to the afterglow ones normalized by the onboard ECL 90% c.l. PSLE up to March 31, 2025. that some systematic effects could be improved with future calibration and/or data analysis software improvements. Onboard, the currently used 90% c.l. PSLE is given by: PSLE90% = q 77′ SNR 2 + syst2 with a systematic error of syst = 2′ . Even if the onboard PSLE90% relation… view at source ↗

read the original abstract

The core instrument of the SVOM Gamma-ray burst mission launched in June 2024 is the 4-150 keV 2-D coded mask camera ECLAIRs responsible for the autonomous trigger and localization of transient events within its field of view. The flight model of ECLAIRs has been built by several French labs (IRAP, CEA, APC) under the supervision of the French Space Agency (CNES), while APC, LUPM and IAP built a suite of data reduction and analysis software. This paper outlines the main science goals of ECLAIRs and describes the different instrument sub-systems and their main characteristics. The paper then discusses the instrument configuration and operation as well as the main in-flight measured performances. Finally, the paper summarizes the science performance of ECLAIRs up to March 31, 2025.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This is a standard instrument description paper for the ECLAIRs coded-mask camera on SVOM, focused on design details and early in-flight performance numbers rather than new science.

read the letter

The paper is a standard instrument description paper for the ECLAIRs coded-mask camera on SVOM, focused on design details and early in-flight performance numbers rather than new science. It covers the flight model built by IRAP, CEA, and APC under CNES oversight, the sub-systems, the 4-150 keV energy range, autonomous triggering goals for GRBs and transients, and measured performance through March 2025 after the June 2024 launch. The software contributions from APC, LUPM, and IAP are also noted. This kind of summary is useful for documenting how the hardware was put together and how it has behaved in orbit so far. The sections on configuration, operation, and basic science goals are straightforward and give a clear picture of what the instrument is meant to do. The in-flight data is the freshest element here. The main limitation is that nothing in the paper is scientifically novel. Coded-mask cameras for transient detection are established from earlier missions, and this is a specific implementation with updated specs for SVOM. The performance claims are factual reporting of measurements, not derivations or model tests, so there are no load-bearing assumptions that could unravel. Minor soft spots include the high-level nature of the performance summary, which would benefit from more explicit error analysis or calibration notes for downstream users, but the paper does not overclaim. This is mainly for SVOM users, GRB observers, and teams building similar high-energy instruments who need the specs and early results as a reference. A reader already following the mission would get practical value from the numbers and design choices. It deserves peer review to check the accuracy of the reported performances and to create a citable record for the community.

Referee Report

1 major / 2 minor

Summary. The manuscript describes the ECLAIRs 4-150 keV coded-mask camera on the SVOM mission (launched June 2024), covering its construction by IRAP, CEA, and APC under CNES supervision, sub-system specifications, data-analysis software, instrument configuration and operation, in-flight measured performances, and a summary of science performance through 31 March 2025.

Significance. If the reported in-flight metrics are supported by the underlying data and calibration details, the paper supplies a necessary reference document for the SVOM high-energy transient program, enabling the community to assess trigger efficiency, localization accuracy, and background behavior for GRB and other transient studies.

major comments (1)

[In-flight measured performances] The abstract and performance summary state that sensitivities and localization accuracies were measured in flight, yet the manuscript provides no quantitative error analysis, systematic uncertainty budget, or comparison to pre-flight expectations in the relevant performance section; this weakens the ability to evaluate whether the quoted numbers are robust.

minor comments (2)

[Science performance summary] The cutoff date of 31 March 2025 should be explicitly tied to a data-release version or observation log so readers know the exact dataset underlying the science-performance summary.
[Instrument sub-systems] Figure captions for the instrument layout and mask pattern should include scale bars or angular scales to aid interpretation of the field-of-view and coding properties.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their detailed review and constructive feedback on our manuscript describing the ECLAIRs instrument. We have addressed the major comment by expanding the relevant section to provide the requested quantitative details on uncertainties.

read point-by-point responses

Referee: The abstract and performance summary state that sensitivities and localization accuracies were measured in flight, yet the manuscript provides no quantitative error analysis, systematic uncertainty budget, or comparison to pre-flight expectations in the relevant performance section; this weakens the ability to evaluate whether the quoted numbers are robust.

Authors: We agree that the original manuscript would be strengthened by a more explicit quantitative treatment of uncertainties in the in-flight performance metrics. In the revised version, we have added a dedicated subsection within the 'In-flight measured performances' section. This subsection now includes: (i) a breakdown of statistical uncertainties derived from the flight data samples used for sensitivity and localization measurements; (ii) a systematic uncertainty budget that accounts for contributions from background subtraction, mask transparency modeling, detector gain stability, and attitude reconstruction; and (iii) a direct comparison of the in-flight results to pre-flight ground calibration campaigns and Monte Carlo simulations, highlighting any observed differences and their implications. These additions allow readers to assess the robustness of the quoted numbers. revision: yes

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper is a factual engineering and operations report describing the ECLAIRs instrument's construction by French labs, sub-system specifications, configuration, operation, and measured in-flight performances up to March 31, 2025. It contains no derivations, equations, predictions, fitted models, or ansatzes that could reduce to their own inputs by construction. Central claims are descriptive summaries of hardware and data rather than inferential results, with no load-bearing self-citations or uniqueness theorems invoked. The paper is self-contained as a standard instrument description against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

This is a technical instrument paper with no mathematical derivations, physical models, or new theoretical entities; all content concerns hardware design and measured performance.

pith-pipeline@v0.9.0 · 5725 in / 991 out tokens · 46079 ms · 2026-05-08T02:03:09.484176+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

40 extracted references · 21 canonical work pages · 1 internal anchor

[1]

et al., 2008, ApJ, 689, 666, 10.1086/592595 6

Ajello, M., Greiner, J., Sato, G. et al., 2008, ApJ, 689, 666, 10.1086/592595 6

work page doi:10.1086/592595 2008
[2]

et al., 2024, GRB Coordinates Network, Circular Service, No

Atteia, J.-L., Bouchet, L., Brunet, M. et al., 2024, GRB Coordinates Network, Circular Service, No. 38557 12

2024
[3]

et al., 2026, in prep

Bouchet, L., Godet, O., Atteia, J.-L. et al., 2026, in prep. 6, 9

2026
[4]

et al., 2026, in prep

Brunet, M., Yang, H., Bouchet, L. et al., 2026, in prep. 2, 11, 12

2026
[5]

Cangemi, F., Zhang, L., 2025, Astronomer’s Telegram, 17251 13

2025
[6]

Brunet, M., Cangemi, F., Guillot, S., Coleiro, A., Zhang, L., 2025, Astronomer’s Telegram, 17385 13

2025
[8]

et al., 2007, A&A, 467, 529, 10.1051/0004-6361:20066230 6

Churazov, E., Sunyaev, R., Revnivtsev, M. et al., 2007, A&A, 467, 529, 10.1051/0004-6361:20066230 6

work page doi:10.1051/0004-6361:20066230 2007
[9]

et al., 2026, IEEE Transactions on Nuclear Science, submitted 5, 6, 7

Claret, A., Bouchet, L., Godet, O. et al., 2026, IEEE Transactions on Nuclear Science, submitted 5, 6, 7

2026
[10]

et al., 2026, RAA, this issue 2, 11, 12, 13

Coleiro, A., Tao, L., Cangemi, F. et al., 2026, RAA, this issue 2, 11, 12, 13

2026
[11]

Y ., Zhang, S.N

Cordier, B., Wei, J. Y ., Zhang, S.N. et al., 2026, RAA, this issue 1, 2, 11 14

2026
[13]

SVOM pointing strategy: how to optimize the redshift measurements?

Cordier, B., Desclaux, F., Foliard, J. and Schanne, S., 2008, GAMMA-RAY BURSTS 2007: Proceedings of the Santa Fe Conference. AIP Conference Proceedings, 1000, 585, arXiv:0807.0739, 10.1063/1.2943538 6

work page doi:10.1063/1.2943538 2008
[15]

et al., 2025, RAA, this issue 2, 11, 12

Daigne, F., Turpin, D., Atteia, J.-L. et al., 2025, RAA, this issue 2, 11, 12

2025
[16]

Galloway, D. K. and Keek, L., 2021, Astrophysics and Space Science Library, 461, 10.1007/978-3-662-62110- 35 12, 13

work page doi:10.1007/978-3-662-62110- 2021
[17]

et al., 2009, IEEE Transactions on Nuclear Science, 56, 2351, 10.1109/TNS.2009.2023989 3

Gevin, O., Baron, P., Coppolani, X. et al., 2009, IEEE Transactions on Nuclear Science, 56, 2351, 10.1109/TNS.2009.2023989 3

work page doi:10.1109/tns.2009.2023989 2009
[18]

et al., 2026, RAA, this issue 2, 3, 4, 5, 7, 8, 11

Godet, O., Atteia, J.-L., Pons, R. et al., 2026, RAA, this issue 2, 3, 4, 5, 7, 8, 11

2026
[19]

On-ground calibration highlights for the SVOM/ECLAIRs camera

Godet, O., Atteia, J.-L., Amoros, C. et al., 2022, Proceedings of SPIE, 12181, 121815O, 10.1117/12.2628932 7, 8, 9

work page doi:10.1117/12.2628932 2022
[20]

The x-/gamma-ray camera ECLAIRs for the gamma-ray burst mission SVOM

Godet, O., Nasser, G., Atteia, J.-L. et al., 2014, Proceedings of SPIE, 9144, 914424, arXiv:1406.7759, 10.1117/12.2055507 1

work page doi:10.1117/12.2055507 2014
[21]

Monte-Carlo simulations of the background of the coded-mask camera for X- and Gamma-rays on-board the Chinese–French GRB mission SVOM

Godet, O., Sizun, P., Barret, D. et al., 2009, Nuclear Instruments and Methods in Physics Research A, 603, 365, 10.1016/j.nima.2009.02.023 2

work page doi:10.1016/j.nima.2009.02.023 2009
[22]

et al., 2026, RAA, this issue 2, 8, 10, 11, 12

Goldwurm, A., Bacon, P., Bellemont, N. et al., 2026, RAA, this issue 2, 8, 10, 11, 12

2026
[23]

Springer Dordrecht, 1988.doi:10.1007/978- 94-009-2871-8

Goldwurm, A. and Gros, A., 2022, Handbook of X-ray and Gamma-ray Astrophysics. Edited by Cosimo Bambi and Andrea Santangelo, Springer Living Reference Work, 978-981-16-4544-0, arXiv:2305.10130, 10.1007/978- 981-16-4544-044-1 2, 10 G¨otz, D., Crepaldi, S., Doumayrou, E. et al., 2026, RAA, this issue 1

work page doi:10.1007/978- 2022
[24]

et al., 2025, GRB Coordinates Network, Circular Service, No

Guillot, S., Cangemi, F., Coleiro, A. et al., 2025, GRB Coordinates Network, Circular Service, No. 40798 12

2025
[25]

G., Briel, U

Kirsch, M. G., Briel, U. G., Burrows, D. et al., 2005, Proceedings of SPIE, 5898, astro-ph/0508235, 10.1117/12.616893 9

work page doi:10.1117/12.616893 2005
[26]

et al., 2026, RAA, this issue 2, 4, 11

Lachaud, C., Givaudan, A., Karakac, M. et al., 2026, RAA, this issue 2, 4, 11

2026
[27]

Development of a 32-detector CdTe matrix for the SVOM ECLAIRs X/Gamma camera: Preliminary results

Lacombe, K., Nasser, G., Amoros, C. et al., 2013, Nuclear Instruments and Methods in Physics Research A, 732, 122, 10.1016/j.nima.2013.07.003 3 Le Stum, S., Cangemi, F., Coleiro, A. et al., 2026, ApJ, 997, L25, 10.3847/2041-8213/ae3174 13

work page doi:10.1016/j.nima.2013.07.003 2013
[28]

Peißker, M

Levan, A. J., Schneider, B., Le Floc’h, E. et al., 2025, A&A Letter, 704, L8, arXiv:2507.18783, 10.1051/0004- 6361/202556581 11

work page doi:10.1051/0004- 2025
[29]

G., Pritchard, R

Lyne, A. G., Pritchard, R. S. and Graham Smith, F., 1993, MNRAS, 265, 1003, 10.1093/mnras/265.4.1003 10

work page doi:10.1093/mnras/265.4.1003 1993
[30]

et al., 2018b, Experimental Astronomy, 46, 337, 10.1007/s10686- 018-9606-1 3, 5, 6, 7 8

Mate, S., Bouchet, L., Atteia, J.-L. et al., 2019, Experimental Astronomy, 48, 171, 10.1007/s10686- 019-09643-x 6

work page doi:10.1007/s10686- 2019
[31]

et al., 2026, RAA, this issue 2, 11

Piron, F., Daigne, F., Maiolino, T. et al., 2026, RAA, this issue 2, 11

2026
[32]

L., Wang, J

Qiu, Y . L., Wang, J. M., Ho, L. C. et al., 2026, RAA, this issue 1

2026
[33]

Sazonov, S., Churazov, E., Sunyaev, R., Revnivtsev, M., 2007, MNRAS, 377, 1726, 10.1111/j.1365- 2966.2007.11746.x 6

work page doi:10.1111/j.1365- 2007
[34]

et al., 2026, RAA, this issue 2, 3, 5, 7, 11

Schanne, S., Chateau, F., Dagoneau, N. et al., 2026, RAA, this issue 2, 3, 5, 7, 11

2026
[35]

and Godet, O., 2024, GRB Coordinates

Schanne, S. and Godet, O., 2024, GRB Coordinates

2024
[36]

XRF 241001A/SN 2024aiiq: A Faint Soft X-ray Transient Detected by SVOM with a Broad-Line Type Ic Supernova Revealed by JWST

Schneider, B. et al., 2026, submitted to A&A, arXiv:2604.20346 12

work page internal anchor Pith review Pith/arXiv arXiv 2026
[37]

Reiners, A., Engeln, A

Shulyak, D. Reiners, A., Engeln, A. et al., 2017, Nature Astronomy, 1, 0184, 10.1038/s41550-017-0184 13

work page doi:10.1038/s41550-017-0184 2017
[38]

and Meegan, C., 2025, GRB Coordinates Network, Circular Service, No

Sonawane, R., Bala S. and Meegan, C., 2025, GRB Coordinates Network, Circular Service, No. 40362 12

2025
[39]

C., Dong, Y

Sun, J. C., Dong, Y . W., He, J. et al., 2025, RAA, this issue 1

2025
[40]

et al., 2011, Phys

Tavani, M., Marisaldi, M., Labanti, C. et al., 2011, Phys. Rev. Lett., 106, 018501, 10.1103/PhysRevLett.106.018501 13 T¨urler, M., Chernyakova, M., Courvoisier, T. J.-L. et al., 2010, A&A, 512, 49, 10.1051/0004-6361/200913072 6

work page doi:10.1103/physrevlett.106.018501 2011
[41]

J., Cangemi, F

Wang, J., Xie, W. J., Cangemi, F. et al., 2026, ApJ, 998, 287, arXiv:2601.16558, 10.48550/arXiv.2601.16558 13

work page doi:10.48550/arxiv.2601.16558 2026
[42]

The Deep and Transient Universe in the SVOM Era: New Challenges and Opportunities - Scientific prospects of the SVOM mission

Wei, J., Cordier, B., Antier, S. et al., 2016,SVOMWhite Paper, arXiv:1610:06892, 10.48550/arXiv.1610.06892 1

work page Pith review doi:10.48550/arxiv.1610.06892 2016
[43]

Zhang, B., 2007, Chinese Journal of Astronomy and Astrophysics, 7, 1, 10.1088/1009-9271/7/1/01 1

work page doi:10.1088/1009-9271/7/1/01 2007