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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"

24353 results found.

  1. GRB 260506B: cubesat Avion detection
  2. GRB 260616C: GECAM-B observation of a burst
  3. GRB 260618A: Fermi GBM Final Real-time Localization
  4. GRB 260617A: Fermi GBM Detection
  5. GRB 260616A: Fermi GBM Observation
  6. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  7. GRB 260617A: Fermi GBM Final Real-time Localization
  8. Konus-Wind detection of GRB 260616B/EP260616a
  9. Konus-Wind detection of GRB 260616A
  10. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  11. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  12. GRB 260616A: GECAM-B observation
  13. GRB 260429A: cubesat Avion detection
  14. GRB 260616A: Fermi-LAT detection
  15. EP260616a: EP-WXT detection of a fast X-ray transient
  16. The EP-WXT trigger 01709270148 is likely a flaring star
  17. GRB 260616B: Fermi GBM Detection
  18. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  19. The EP-WXT trigger 01709269893 is likely a flaring star
  20. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  21. GRB 260616A: Fermi GBM Final Real-time Localization
  22. GRB 260614B: SVOM/ECLAIRs refined analysis
  23. GRB 260614B: GECAM-B observation
  24. GRB 260610B: SVOM/GRM observation
  25. GRB 260614B: SVOM/VT optical afterglow confirmation
  26. GRB 260614B: Fermi GBM Observation
  27. GRB 260614B: SVOM/VT optical candidate from VHF data
  28. GRB 260614B: SVOM detection of a burst
  29. GRB 260614B: Fermi GBM Final Real-time Localization
  30. GRB 260611B: SVOM/GRM detection
  31. GRB 260614A: Fermi GBM Final Localization
  32. The EP-WXT trigger 01709269488 is likely a flaring star
  33. GRB 260610B: Fermi GBM Observation
  34. EP260605a: COLIBRÍ optical upper limits
  35. EP260610b: Liverpool Telescope optical upper limits
  36. IceCube-260610A: No candidates from the Zwicky Transient Facility
  37. IceCube-260610A: EP-FXT follow-up observation
  38. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  39. GRB 260610B / AT2026owq: SVOM/VT optical observations
  40. GRB 260611B: Fermi GBM Final Real-time Localization
  41. EP260610b: GTC likely spectroscopic redshift z = 1.10
  42. The EP-WXT trigger 01709269176 is likely a flaring star
  43. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  44. GRB 260610B / AT2026owq: Early ATLAS observations
  45. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  46. GRB 260611A: Fermi GBM Final Real-time Localization
  47. GRB 260610B: GOTO optical counterpart candidate
  48. GRB 260610B: Fermi GBM Final Localization
  49. EP260610b: SVOM/VT optical confirmation with blue color
  50. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 260515A: SOAR optical observations
  52. EP260610a: SVOM/VT optical upper limits
  53. Konus-Wind detection of GRB 260601A
  54. IPN triangulation of GRB 260601A (short/hard)
  55. GRB 260610A: Fermi GBM Final Real-time Localization (duplicate submission)
  56. GRB 260610A: Fermi GBM Final Real-time Localization
  57. GRB 260609A: Fermi GBM Final Localization
  58. Konus-Wind detection of GRB 260604C
  59. GRB 260608A: Fermi GRB Observation
  60. IPN triangulation of GRB 260601B / EP260601a
  61. GRB 260604C: SVOM/ECLAIRs refined analysis
  62. GRB 260608A: SVOM/ECLAIRs refined analysis
  63. Konus-Wind detection of GRB 260607B
  64. GRB 260607B: GECAM-B observation
  65. GRB 260608C: Fermi GBM Final Real-time Localization (duplicate submission)
  66. GRB 260608C: Fermi GBM Final Real-time Localization
  67. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  68. GRB 260608B: Fermi GBM Final Localization
  69. GRB 260604C: SVOM/C-GFT upper limit
  70. GRB 260608A: SVOM detection of a burst
  71. GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
  72. GRB 260608A: Fermi GBM Final Real-time Localization
  73. EP260605a: EP-FXT follow-up observation
  74. GRB 260607A: TRT optical observations
  75. GRB 260604C: GRANDMA further observations
  76. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  77. GRB 260604A: SVOM/GRM detection
  78. GRB 260607B: Fermi GBM Observation
  79. GRB 260607B: Fermi-LAT detection
  80. GRB 260607B: Fermi GBM Final Localization Correction
  81. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  82. GRB 260607A: Fermi GBM Final Real-time Localization
  83. GRB 260604C: GECAM-B observation
  84. GRB 260604B: SVOM/GRM detection
  85. GRB260603A: SVOM/ECLAIRs refined analysis
  86. GRB 260604C: LCO optical upper limit
  87. The EP-WXT trigger 01709267001 is likely a flaring star
  88. EP260602d: EP-FXT follow-up observation
  89. EP260602c: EP-FXT follow-up observation
  90. GRB 260604C: GOTO detections of the optical afterglow
  91. The EP-WXT trigger 01709266798 is likely a flaring star
  92. GRB 260604C: Fermi GBM Observation
  93. EP260602d: J-band upper limit with WINTER
  94. Fermi GRB 260604C: Global MASTER-Net observations report
  95. Fermi GRB 260604C: Global MASTER-Net observations report
  96. SVOM GRB260604.85: Global MASTER-Net observations report
  97. GRB 260604C: SVOM detection of a long burst
  98. GRB 260604C: Fermi GBM Final Real-time Localization
  99. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  100. GRB 260604B: Fermi GBM Final Real-time Localization

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