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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"

12283 results found.

  1. GRB 260607B: Fermi GBM Observation
  2. GRB 260607B: Fermi-LAT detection
  3. GRB 260607B: Fermi GBM Final Localization Correction
  4. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  5. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  6. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  7. GRB 260607A: Fermi GBM Final Real-time Localization
  8. GRB 260604C: GECAM-B observation
  9. GRB 260604C: 6 GHz VLA observations
  10. GRB 260604C: SAO RAS optical observations
  11. GRB 260604C: GRANDMA observations
  12. GRB 260604B: SVOM/GRM detection
  13. GRB 260604A: Glowbug gamma-ray detection
  14. GRB 260604C: LCO optical upper limit
  15. GRB 260604C: Liverpool Telescope optical detection
  16. GRB 260604C: GOTO detections of the optical afterglow
  17. GRB 260604C: Kilonova-Catcher optical afterglow detection
  18. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. GRB 260604C: Jinshan optical observations
  20. GRB 260604C: Fermi GBM Observation
  21. GRB 260604C: LAST detection of optical counterpart candidate
  22. Fermi GRB 260604C: Global MASTER-Net observations report
  23. Fermi GRB 260604C: Global MASTER-Net observations report
  24. GRB 260604C: SVOM detection of a long burst
  25. GRB 260604C: Fermi GBM Final Real-time Localization
  26. GRB 260604B: Fermi GBM Final Real-time Localization
  27. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  28. GRB 260604A: Fermi GBM Final Real-time Localization
  29. GRB 260603B: Fermi GBM Final Localization
  30. Fermi trigger No 802141998: Global MASTER-Net observations report
  31. GRB 260601A: SVOM/GRM observation of a short burst
  32. Fermi GRB 260602B: Global MASTER-Net observations report
  33. Fermi GRB 260602B: Global MASTER-Net observations report
  34. GRB 260602B: Fermi GBM Final Localization
  35. GRB 260601A: GECAM-B observation of a short burst
  36. GRB 260602A: Fermi GBM Final Real-time Localization
  37. GRB 260601A: Glowbug gamma-ray detection of a short burst
  38. GRB 260531B: Glowbug gamma-ray detection
  39. GRB 260601A: Fermi GBM Observation
  40. Fermi GRB 260601A: Global MASTER-Net observations report
  41. GRB 260601A: Fermi GBM Final Real-time Localization
  42. GRB 260531B: GECAM-B observation
  43. GRB 260531C: Fermi GBM Final Localization Correction
  44. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  45. Fermi trigger No 801900520: Global MASTER-Net observations report
  46. GRB 260531B: Fermi GBM Final Real-time Localization
  47. AT 2026nuz: COLIBRÍ optical observations
  48. GRB 260530A: Fermi GBM Final Real-time Localization
  49. GRB 260529A: GOTO tentative optical afterglow candidate
  50. Fermi GRB 260529A: Global MASTER-Net observations report
  51. GRB 260529A: Fermi GBM Final Real-time Localization
  52. GRB 260526A: GECAM-B observation
  53. Fermi trigger No 801580882: Global MASTER-Net observations report
  54. GRB 260525A: AstroSat CZTI detection
  55. Fermi GRB 260526A: Global MASTER-Net observations report
  56. GRB 260526A: Fermi GBM Final Real-time Localization
  57. Fermi GRB 260525A: Global MASTER-Net observations report
  58. GRB 260525A: Fermi GBM Final Real-time Localization
  59. GRB 260523B: AstroSat CZTI detection
  60. GRB 260523B: GECAM-B observation
  61. Fermi GRB 260523A: Global MASTER-Net observations report
  62. GRB 260523B: Fermi GBM Final Real-time Localization
  63. GRB 260523A: Fermi GBM Final Real-time Localization
  64. GRB 260522A: Fermi GBM Observation
  65. GRB 260522B: NuSTAR detection of prompt emission
  66. GRB 260522B: Fermi GBM Final Real-time Localization
  67. GRB 260522A: GOTO optical upper limit
  68. Fermi trigger No 801135305: Global MASTER-Net observations report
  69. Fermi GRB 260522A: Global MASTER-Net observations report
  70. GRB 260522A: Fermi-LAT detection
  71. GRB 260522A: Fermi GBM Final Real-time Localization
  72. GRB 260511A: iTelescope T-75 optical detection
  73. GRB 260520B: SVOM/GRM observation
  74. GRB 260411B: TERI Gamma-ray detection
  75. GRB 260407A: TERI Gamma-ray detection
  76. GRB 260307A: TERI Gamma-ray detection
  77. GRB 251118A: TERI Gamma-ray detection
  78. GRB 251113A: TERI Gamma-ray detection
  79. GRB 260428A: TERI Gamma-ray detection
  80. GRB 260520B: Fermi GBM Final Localization
  81. GRB 260520A: Fermi GBM Final Localization
  82. GRB 260519D: Fermi GBM Final Localization Correction
  83. GRB 260519B: Fermi GBM Final Localization
  84. GRB 260519A: Fermi GBM Final Localization
  85. GRB 260421B: radio detection with the VLA
  86. GRID detection of GRB 260511A
  87. Fermi GRB 260516C: Global MASTER-Net observations report
  88. GRB 260516C: Fermi GBM Final Real-time Localization
  89. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  90. Fermi GRB 260516B: Global MASTER-Net observations report
  91. GRB 260516B: Fermi GBM Final Real-time Localization
  92. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  93. GRB 260516A: Fermi GBM Final Real-time Localization
  94. GRID detection of GRB 260507A
  95. GRB 260510C: Glowbug gamma-ray detection
  96. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  97. GRB 260511B: NOT optical observations
  98. Konus-Wind detection of GRB 260512A
  99. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  100. IPN triangulation of GRB 260512A

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