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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"

45435 results found.

  1. IPN triangulation of GRB 260617A (short)
  2. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  3. GRB 260616A: Insight-HXMT detection
  4. GRB 260618B: Fermi GBM Final Real-time Localization
  5. EP260618a: EP-WXT detection of an X-ray transient
  6. GRB 260610B: AbAO optical observations
  7. EP260616a/GRB 260616B: EP-FXT follow-up observation
  8. GRB 260506B: cubesat Avion detection
  9. GRB 260616C: GECAM-B observation of a burst
  10. GRB 260618A: Fermi GBM Final Real-time Localization
  11. GRB 260617A: Fermi GBM Detection
  12. GRB 260616A: Fermi GBM Observation
  13. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  14. GRB 260617A: Fermi GBM Final Real-time Localization
  15. Konus-Wind detection of GRB 260616B/EP260616a
  16. Konus-Wind detection of GRB 260616A
  17. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  18. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  19. GRB 260616A: GECAM-B observation
  20. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  21. GRB 260429A: cubesat Avion detection
  22. GRB260616C: MAXI/GSC detection
  23. GRB 260616A: Fermi-LAT detection
  24. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  25. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  26. GRB 260614A: AstroSat CZTI detection
  27. EP260616a: EP-WXT detection of a fast X-ray transient
  28. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  29. The EP-WXT trigger 01709270148 is likely a flaring star
  30. GRB 260616B: Fermi GBM Detection
  31. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  32. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  33. The EP-WXT trigger 01709269893 is likely a flaring star
  34. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  35. GRB 260616A: Fermi GBM Final Real-time Localization
  36. GRB 260614B: SVOM/ECLAIRs refined analysis
  37. GRB 260610B: Terskol optical observations
  38. GRB 260614B: GECAM-B observation
  39. GRB 260610B: SVOM/GRM observation
  40. GRB 260614B: SVOM/VT optical afterglow confirmation
  41. GRB 260614B: Fermi GBM Observation
  42. GRB 260610B: ALMA detection
  43. GRB 260614A: GECAM-B observation
  44. GRB 260614B: SVOM/VT optical candidate from VHF data
  45. GRB 260614B: SVOM detection of a burst
  46. GRB 260614B: Fermi GBM Final Real-time Localization
  47. GRB 260611B: SVOM/GRM detection
  48. GRB 260614A: Fermi GBM Final Localization
  49. The EP-WXT trigger 01709269488 is likely a flaring star
  50. GRB 260603C: AstroSat CZTI detection
  51. GRB 260610B: further Liverpool Telescope optical observations
  52. GRB 260610B: Fermi GBM Observation
  53. GRB 260610B / AT2026owq: GRANDMA optical observations
  54. GRB 260610B / AT2026owq: further SAO RAS optical observations
  55. EP260605a: COLIBRÍ optical upper limits
  56. GRB 260610b: Liverpool Telescope optical observations
  57. EP260610b: Liverpool Telescope optical upper limits
  58. IceCube-260610A: No candidates from the Zwicky Transient Facility
  59. IceCube-260610A: EP-FXT follow-up observation
  60. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  61. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  62. GRB 260610B / AT2026owq: SVOM/VT optical observations
  63. GRB 260610B / AT2026owq: OASDG optical observations
  64. GRB 260610B: IAC-80 Optical observations
  65. GRB 260610B / AT2026owq: SAO RAS optical observations
  66. GRB 260611B: Fermi GBM Final Real-time Localization
  67. EP260601a: VLT/X-shooter spectroscopic host galaxy redshift z = 1.068
  68. EP260610b: GTC likely spectroscopic redshift z = 1.10
  69. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  70. The EP-WXT trigger 01709269176 is likely a flaring star
  71. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  72. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  73. GRB 260610B / AT2026owq: Early ATLAS observations
  74. GRB 260610B: TRT optical observation
  75. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  76. GRB 260611A: Fermi GBM Final Real-time Localization
  77. EP260610b: COLIBRÍ optical observations
  78. GRB 260610B: DDOTI optical observations
  79. EP260610b: MAO/AZT-22 optical observations
  80. GRB 260610B: GOTO optical counterpart candidate
  81. EP260610b: NOT optical observation
  82. GRB 260610B: Fermi GBM Final Localization
  83. EP260610b: SVOM/VT optical confirmation with blue color
  84. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260515A: SOAR optical observations
  86. EP260610b: Gemini North optical counterpart candidate
  87. EP260610a: SVOM/VT optical upper limits
  88. EP260610b: Einstein Probe detection of an X-ray transient
  89. Konus-Wind detection of GRB 260601A
  90. IPN triangulation of GRB 260601A (short/hard)
  91. GRB 260610A: Fermi GBM Final Real-time Localization (duplicate submission)
  92. GRB 260610A: Fermi GBM Final Real-time Localization
  93. EP260610a: COLIBRÍ optical upper limits
  94. EP260610a: Einstein Probe detection of a fast X-ray transient
  95. GRB 260609A: Fermi GBM Final Localization
  96. Konus-Wind detection of GRB 260604C
  97. GRB 260608A: Fermi GRB Observation
  98. GRB 260604C: AstroSat CZTI detection
  99. IPN triangulation of GRB 260601B / EP260601a
  100. GRB 260604C: SVOM/ECLAIRs refined analysis

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