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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"

24362 results found.

  1. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 260616A: NuSTAR detection of prompt emission
  3. GRB 260614B: NuSTAR detection of prompt emission
  4. GRB 260619A: SVOM possible detection of a faint burst
  5. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 260618B: Fermi-LAT detection
  7. IPN triangulation of GRB 260617A (short)
  8. GRB 260618B: Fermi GBM Final Real-time Localization
  9. EP260616a/GRB 260616B: EP-FXT follow-up observation
  10. GRB 260506B: cubesat Avion detection
  11. GRB 260616C: GECAM-B observation of a burst
  12. GRB 260618A: Fermi GBM Final Real-time Localization
  13. GRB 260617A: Fermi GBM Detection
  14. GRB 260616A: Fermi GBM Observation
  15. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  16. GRB 260617A: Fermi GBM Final Real-time Localization
  17. Konus-Wind detection of GRB 260616B/EP260616a
  18. Konus-Wind detection of GRB 260616A
  19. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  20. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  21. GRB 260616A: GECAM-B observation
  22. GRB 260429A: cubesat Avion detection
  23. GRB 260616A: Fermi-LAT detection
  24. EP260616a: EP-WXT detection of a fast X-ray transient
  25. The EP-WXT trigger 01709270148 is likely a flaring star
  26. GRB 260616B: Fermi GBM Detection
  27. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  28. The EP-WXT trigger 01709269893 is likely a flaring star
  29. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  30. GRB 260616A: Fermi GBM Final Real-time Localization
  31. GRB 260614B: SVOM/ECLAIRs refined analysis
  32. GRB 260614B: GECAM-B observation
  33. GRB 260610B: SVOM/GRM observation
  34. GRB 260614B: SVOM/VT optical afterglow confirmation
  35. GRB 260614B: Fermi GBM Observation
  36. GRB 260614B: SVOM/VT optical candidate from VHF data
  37. GRB 260614B: SVOM detection of a burst
  38. GRB 260614B: Fermi GBM Final Real-time Localization
  39. GRB 260611B: SVOM/GRM detection
  40. GRB 260614A: Fermi GBM Final Localization
  41. The EP-WXT trigger 01709269488 is likely a flaring star
  42. GRB 260610B: Fermi GBM Observation
  43. EP260605a: COLIBRÍ optical upper limits
  44. EP260610b: Liverpool Telescope optical upper limits
  45. IceCube-260610A: No candidates from the Zwicky Transient Facility
  46. IceCube-260610A: EP-FXT follow-up observation
  47. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  48. GRB 260610B / AT2026owq: SVOM/VT optical observations
  49. GRB 260611B: Fermi GBM Final Real-time Localization
  50. EP260610b: GTC likely spectroscopic redshift z = 1.10
  51. The EP-WXT trigger 01709269176 is likely a flaring star
  52. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  53. GRB 260610B / AT2026owq: Early ATLAS observations
  54. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  55. GRB 260611A: Fermi GBM Final Real-time Localization
  56. GRB 260610B: GOTO optical counterpart candidate
  57. GRB 260610B: Fermi GBM Final Localization
  58. EP260610b: SVOM/VT optical confirmation with blue color
  59. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  60. GRB 260515A: SOAR optical observations
  61. EP260610a: SVOM/VT optical upper limits
  62. Konus-Wind detection of GRB 260601A
  63. IPN triangulation of GRB 260601A (short/hard)
  64. GRB 260610A: Fermi GBM Final Real-time Localization (duplicate submission)
  65. GRB 260610A: Fermi GBM Final Real-time Localization
  66. GRB 260609A: Fermi GBM Final Localization
  67. Konus-Wind detection of GRB 260604C
  68. GRB 260608A: Fermi GRB Observation
  69. IPN triangulation of GRB 260601B / EP260601a
  70. GRB 260604C: SVOM/ECLAIRs refined analysis
  71. GRB 260608A: SVOM/ECLAIRs refined analysis
  72. Konus-Wind detection of GRB 260607B
  73. GRB 260607B: GECAM-B observation
  74. GRB 260608C: Fermi GBM Final Real-time Localization (duplicate submission)
  75. GRB 260608C: Fermi GBM Final Real-time Localization
  76. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  77. GRB 260608B: Fermi GBM Final Localization
  78. GRB 260604C: SVOM/C-GFT upper limit
  79. GRB 260608A: SVOM detection of a burst
  80. GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
  81. GRB 260608A: Fermi GBM Final Real-time Localization
  82. EP260605a: EP-FXT follow-up observation
  83. GRB 260607A: TRT optical observations
  84. GRB 260604C: GRANDMA further observations
  85. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  86. GRB 260604A: SVOM/GRM detection
  87. GRB 260607B: Fermi GBM Observation
  88. GRB 260607B: Fermi-LAT detection
  89. GRB 260607B: Fermi GBM Final Localization Correction
  90. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  91. GRB 260607A: Fermi GBM Final Real-time Localization
  92. GRB 260604C: GECAM-B observation
  93. GRB 260604B: SVOM/GRM detection
  94. GRB260603A: SVOM/ECLAIRs refined analysis
  95. GRB 260604C: LCO optical upper limit
  96. The EP-WXT trigger 01709267001 is likely a flaring star
  97. EP260602d: EP-FXT follow-up observation
  98. EP260602c: EP-FXT follow-up observation
  99. GRB 260604C: GOTO detections of the optical afterglow
  100. The EP-WXT trigger 01709266798 is likely a flaring star

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