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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"

28068 results found.

  1. GRB 260617A: Fermi GBM Detection
  2. GRB 260617A: Fermi GBM Final Real-time Localization
  3. Konus-Wind detection of GRB 260616B/EP260616a
  4. Konus-Wind detection of GRB 260616A
  5. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  6. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  7. GRB 260429A: cubesat Avion detection
  8. GRB260616C: MAXI/GSC detection
  9. GRB 260616A: Fermi-LAT detection
  10. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  11. GRB 260614A: AstroSat CZTI detection
  12. EP260616a: EP-WXT detection of a fast X-ray transient
  13. GRB 260616B: Fermi GBM Detection
  14. GRB 260616A: Fermi GBM Final Real-time Localization
  15. GRB 260614B: SVOM/VT optical afterglow confirmation
  16. GRB 260610B: ALMA detection
  17. GRB 260614B: SVOM detection of a burst
  18. GRB 260614B: Fermi GBM Final Real-time Localization
  19. GRB 260611B: SVOM/GRM detection
  20. GRB 260614A: Fermi GBM Final Localization
  21. GRB 260603C: AstroSat CZTI detection
  22. GRB 260610B / AT2026owq: GRANDMA optical observations
  23. EP260610b: Liverpool Telescope optical upper limits
  24. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  25. GRB 260610B: IAC-80 Optical observations
  26. GRB 260611B: Fermi GBM Final Real-time Localization
  27. GRB 260610B / AT2026owq: Early ATLAS observations
  28. GRB 260611A: Fermi GBM Final Real-time Localization
  29. GRB 260610B: DDOTI optical observations
  30. GRB 260610B: Fermi GBM Final Localization
  31. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  32. EP260610a: SVOM/VT optical upper limits
  33. EP260610b: Einstein Probe detection of an X-ray transient
  34. Konus-Wind detection of GRB 260601A
  35. IPN triangulation of GRB 260601A (short/hard)
  36. GRB 260610A: Fermi GBM Final Real-time Localization
  37. EP260610a: Einstein Probe detection of a fast X-ray transient
  38. GRB 260609A: Fermi GBM Final Localization
  39. Konus-Wind detection of GRB 260604C
  40. GRB 260604C: AstroSat CZTI detection
  41. IPN triangulation of GRB 260601B / EP260601a
  42. GRB 260604C: SVOM/ECLAIRs refined analysis
  43. Konus-Wind detection of GRB 260607B
  44. GRB 260608C: Fermi GBM Final Real-time Localization
  45. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  46. GRB 260608B: Fermi GBM Final Localization
  47. GRB 260607B: AstroSat CZTI detection
  48. GRB 260608A: SVOM detection of a burst
  49. GRB 260608A: Fermi GBM Final Real-time Localization
  50. EP260605a: EP-FXT follow-up observation
  51. GRB 260604A: SVOM/GRM detection
  52. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  53. GRB 260607B: Fermi-LAT detection
  54. GRB 260607B: Fermi GBM Final Localization Correction
  55. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  56. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  57. GRB 260607A: Fermi GBM Final Real-time Localization
  58. GRB 260604C: GRANDMA observations
  59. GRB 260604B: SVOM/GRM detection
  60. GRB 260605A: Insight-HXMT/HE detection
  61. EP260605a: Einstein Probe detection of a fast X-ray transient
  62. GRB 260604A: Glowbug gamma-ray detection
  63. GRB 260604C: Liverpool Telescope optical detection
  64. EP260602d: EP-FXT follow-up observation
  65. EP260602c: EP-FXT follow-up observation
  66. GRB 260601B / EP260601a: AstroSat CZTI detection
  67. GRB 260527A/EP260527a: 6 GHz VLA observations
  68. GRB 260604C: GOTO detections of the optical afterglow
  69. GRB 260604C: Correction to GCN 44828
  70. GRB 260604C: Kilonova-Catcher optical afterglow detection
  71. GRB 260604C: LAST detection of optical counterpart candidate
  72. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  73. GRB 260604C: SVOM detection of a long burst
  74. GRB 260604C: Fermi GBM Final Real-time Localization
  75. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  76. GRB 260603A: NOT optical observations
  77. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  78. GRB 260604B: Fermi GBM Final Real-time Localization
  79. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  80. EP260602a: EP-FXT follow-up observation
  81. EP260603a: Einstein Probe detection of a fast X-ray transient
  82. EP260602d: Optical Upper limits with kinder observations
  83. GRB 260604A: Fermi GBM Final Real-time Localization
  84. EP260602b: Liverpool Telescope observations
  85. GRB 260603B: Fermi GBM Final Localization
  86. Konus-Wind detection of GRB 260601B/EP260601a
  87. EP260602b: EP-FXT follow-up observation
  88. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  89. EP260602d: Einstein Probe detection of a fast X-ray transient
  90. EP260602c: Einstein Probe detection of a fast X-ray transient
  91. EP260602a: COLIBRÍ optical observations
  92. GRB 260603A: SVOM detection of a burst
  93. EP260602b: Einstein Probe detection of a fast X-ray transient
  94. GRB 260601B/EP260601a: Insight-HXMT detection
  95. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  96. GRB 260602B: Fermi GBM Final Localization
  97. GRB 260602A: Fermi GBM Final Real-time Localization
  98. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  99. EP260602a: Optical upper limits with Kinder observations
  100. GRB 260601B / EP260601a: NuSTAR detection of prompt emission

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