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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"

28067 results found.

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

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