Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28926 results found.

  1. SVOM GRB260604.85: Global MASTER-Net observations report
  2. GRB 260604C: SVOM detection of a long burst
  3. GRB 260604C: Fermi GBM Final Real-time Localization
  4. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  5. GRB 260603A: NOT optical observations
  6. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  7. GRB 260604B: Fermi GBM Final Real-time Localization
  8. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  9. EP260603a: Global MASTER-Net observations report
  10. GRB 260604A: Fermi GBM Final Real-time Localization
  11. EP260602b: Liverpool Telescope observations
  12. EP260602a: Liverpool Telescope optical upper limits
  13. GRB 260603B: Fermi GBM Final Localization
  14. GRB 260603A: EP-FXT follow-up observation
  15. EP260601a/GRB 260601B: EP-FXT follow-up observation
  16. GRB 260603A: SVOM/VT optical observations
  17. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  18. EP260602d: Einstein Probe detection of a fast X-ray transient
  19. Fermi trigger No 802141998: Global MASTER-Net observations report
  20. GRB 260601A: SVOM/GRM observation of a short burst
  21. EP260602c: Einstein Probe detection of a fast X-ray transient
  22. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  23. EP260602a: COLIBRÍ optical observations
  24. GRB260601B/EP260601a: NOT near-infrared observations
  25. SVOM GRB260603.23: Global MASTER-Net observations report
  26. GRB 260603A: SVOM detection of a burst
  27. Fermi GRB 260602B: Global MASTER-Net observations report
  28. Fermi GRB 260602B: Global MASTER-Net observations report
  29. EP260602a: SVOM/VT optical candidate
  30. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  31. GRB 260602B: Fermi GBM Final Localization
  32. GRB 260601A: GECAM-B observation of a short burst
  33. GRB 260601B/EP260601a: J-band upper limit with WINTER
  34. GRB 260602A: Fermi GBM Final Real-time Localization
  35. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  36. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  37. GRB 260601B/EP260601a: SVOM/VT optical observations
  38. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  39. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  40. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  41. GRB 260601A: Glowbug gamma-ray detection of a short burst
  42. GRB 260531B: Glowbug gamma-ray detection
  43. GRB 260516D: VLA radio detection
  44. GRB 260601A: Fermi GBM Observation
  45. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  46. Fermi GRB 260601A: Global MASTER-Net observations report
  47. GRB 260601A: Fermi GBM Final Real-time Localization
  48. GRB 260531B: GECAM-B observation
  49. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  50. The EP-WXT trigger 01709266272 is likely a flaring star
  51. GRB 260531C: Fermi GBM Final Localization Correction
  52. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  53. Fermi trigger No 801900520: Global MASTER-Net observations report
  54. GRB 260531B: Fermi GBM Final Real-time Localization
  55. AT 2026nuz: COLIBRÍ optical observations
  56. IPN triangulation of GRB 260527A / EP260527a
  57. EP260527a/GRB 260527A: further FTW optical and NIR observations
  58. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  59. GRB 260530A: Fermi GBM Final Real-time Localization
  60. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  61. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  62. GRB 260529A: GOTO tentative optical afterglow candidate
  63. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  64. Fermi GRB 260529A: Global MASTER-Net observations report
  65. GRB 260529A: Fermi GBM Final Real-time Localization
  66. EP260526a: SVOM/VT optical upper limits
  67. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  68. EP260527a / GRB 260527A: NOT optical observations
  69. GRB 260527A/EP260527a: FTW optical and NIR observations
  70. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  71. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  72. GRB 260526A: GECAM-B observation
  73. EP260527a: SVOM/VT optical observation
  74. EP260527a: COLIBRÍ optical detection
  75. EP260527a: Einstein Probe detection of a fast X-ray transient
  76. The EP-WXT trigger 01709266172 is likely a flaring star
  77. The EP-WXT trigger 01709266147 is likely a flaring star
  78. Fermi trigger No 801580882: Global MASTER-Net observations report
  79. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  80. EP260526a: Einstein Probe detection of a fast X-ray transient
  81. GRB 260525A: AstroSat CZTI detection
  82. EP260526.405: COLIBRÍ optical upper limits
  83. The EP-WXT trigger 01709266106 is not a real source
  84. Fermi GRB 260526A: Global MASTER-Net observations report
  85. GRB 260526A: Fermi GBM Final Real-time Localization
  86. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  87. EP-WXT 01709266106: NOT optical upper limits
  88. Fermi GRB 260525A: Global MASTER-Net observations report
  89. GRB 260525A: Fermi GBM Final Real-time Localization
  90. GRB 260523B: AstroSat CZTI detection
  91. GRB 260523B: GECAM-B observation
  92. Fermi GRB 260523A: Global MASTER-Net observations report
  93. GRB 260523B: Fermi GBM Final Real-time Localization
  94. GRB 260523A: Fermi GBM Final Real-time Localization
  95. GRB 260522A: Fermi GBM Observation
  96. GRB 260522B: NuSTAR detection of prompt emission
  97. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  98. GRB 260522B: Fermi GBM Final Real-time Localization
  99. GRB 260522A: GOTO optical upper limit
  100. Fermi trigger No 801135305: Global MASTER-Net observations report

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov