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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"

24278 results found.

  1. GRB 260618B: LCO optical observations
  2. The EP-WXT trigger 01709271197 is likely a flaring star
  3. EP260618a: JinShan optical observations
  4. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  5. GRB 260618B: Fermi GBM Observation
  6. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 260619A: TRT optical counterpart confirmation
  8. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  9. GRB 260619A: SVOM/VT optical counterpart confirmation
  10. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  11. GRB 260618B: SVOM/VT optical candidate
  12. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  13. Konus-Wind detection of GRB 260617A
  14. GRB 260616A: SVOM/GRM observation
  15. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  16. EP260618a: EP-FXT follow-up observation
  17. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 260616A: NuSTAR detection of prompt emission
  19. GRB 260614B: NuSTAR detection of prompt emission
  20. GRB 260619A: SVOM possible detection of a faint burst
  21. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 260618B: Fermi-LAT detection
  23. IPN triangulation of GRB 260617A (short)
  24. GRB 260618B: Fermi GBM Final Real-time Localization
  25. EP260616a/GRB 260616B: EP-FXT follow-up observation
  26. GRB 260506B: cubesat Avion detection
  27. GRB 260616C: GECAM-B observation of a burst
  28. GRB 260618A: Fermi GBM Final Real-time Localization
  29. GRB 260617A: Fermi GBM Detection
  30. GRB 260616A: Fermi GBM Observation
  31. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  32. GRB 260617A: Fermi GBM Final Real-time Localization
  33. Konus-Wind detection of GRB 260616B/EP260616a
  34. Konus-Wind detection of GRB 260616A
  35. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  36. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  37. GRB 260616A: GECAM-B observation
  38. GRB 260429A: cubesat Avion detection
  39. GRB 260616A: Fermi-LAT detection
  40. EP260616a: EP-WXT detection of a fast X-ray transient
  41. The EP-WXT trigger 01709270148 is likely a flaring star
  42. GRB 260616B: Fermi GBM Detection
  43. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  44. The EP-WXT trigger 01709269893 is likely a flaring star
  45. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  46. GRB 260616A: Fermi GBM Final Real-time Localization
  47. GRB 260614B: SVOM/ECLAIRs refined analysis
  48. GRB 260614B: GECAM-B observation
  49. GRB 260610B: SVOM/GRM observation
  50. GRB 260614B: SVOM/VT optical afterglow confirmation
  51. GRB 260614B: Fermi GBM Observation
  52. GRB 260614B: SVOM/VT optical candidate from VHF data
  53. GRB 260614B: SVOM detection of a burst
  54. GRB 260614B: Fermi GBM Final Real-time Localization
  55. GRB 260611B: SVOM/GRM detection
  56. GRB 260614A: Fermi GBM Final Localization
  57. The EP-WXT trigger 01709269488 is likely a flaring star
  58. GRB 260610B: Fermi GBM Observation
  59. EP260605a: COLIBRÍ optical upper limits
  60. EP260610b: Liverpool Telescope optical upper limits
  61. IceCube-260610A: No candidates from the Zwicky Transient Facility
  62. IceCube-260610A: EP-FXT follow-up observation
  63. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  64. GRB 260610B / AT2026owq: SVOM/VT optical observations
  65. GRB 260611B: Fermi GBM Final Real-time Localization
  66. EP260610b: GTC likely spectroscopic redshift z = 1.10
  67. The EP-WXT trigger 01709269176 is likely a flaring star
  68. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  69. GRB 260610B / AT2026owq: Early ATLAS observations
  70. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  71. GRB 260611A: Fermi GBM Final Real-time Localization
  72. GRB 260610B: GOTO optical counterpart candidate
  73. GRB 260610B: Fermi GBM Final Localization
  74. EP260610b: SVOM/VT optical confirmation with blue color
  75. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 260515A: SOAR optical observations
  77. EP260610a: SVOM/VT optical upper limits
  78. Konus-Wind detection of GRB 260601A
  79. IPN triangulation of GRB 260601A (short/hard)
  80. GRB 260610A: Fermi GBM Final Real-time Localization (duplicate submission)
  81. GRB 260610A: Fermi GBM Final Real-time Localization
  82. GRB 260609A: Fermi GBM Final Localization
  83. Konus-Wind detection of GRB 260604C
  84. GRB 260608A: Fermi GRB Observation
  85. IPN triangulation of GRB 260601B / EP260601a
  86. GRB 260604C: SVOM/ECLAIRs refined analysis
  87. GRB 260608A: SVOM/ECLAIRs refined analysis
  88. Konus-Wind detection of GRB 260607B
  89. GRB 260607B: GECAM-B observation
  90. GRB 260608C: Fermi GBM Final Real-time Localization (duplicate submission)
  91. GRB 260608C: Fermi GBM Final Real-time Localization
  92. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  93. GRB 260608B: Fermi GBM Final Localization
  94. GRB 260604C: SVOM/C-GFT upper limit
  95. GRB 260608A: SVOM detection of a burst
  96. GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
  97. GRB 260608A: Fermi GBM Final Real-time Localization
  98. EP260605a: EP-FXT follow-up observation
  99. GRB 260607A: TRT optical observations
  100. GRB 260604C: GRANDMA further observations

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