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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

36106 results found.

  1. GRB 260706A: Fermi GBM Observation
  2. IPN triangulation of GRB 260627A
  3. GRB 260705A: SVOM/ECLAIRs refined analysis
  4. GRB 260706A: SVOM detection of a burst
  5. GRB 260706A: Fermi GBM Final Real-time Localization
  6. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  7. GRB 260705A: LCO optical upper limits
  8. GRB 260704A: NOT optical upper limits
  9. GRB 260705C: Fermi GBM Final Localization
  10. GRB 260705B: Fermi GBM Final Real-time Localization
  11. Fermi GBM Sub-Threshold Detection of GRB 260705A
  12. GRB 260705A: SVOM detection of a burst
  13. GRB 260704A: EP-FXT follow-up observation
  14. GRB 260629A: SVOM/GRM observation of a short burst
  15. GRB 260629A: GECAM-A observation of a short burst
  16. GRB 260629A: AstroSat CZTI detection
  17. GRB 260704A: SVOM detection of a possible GRB
  18. GRB 260703B: Fermi GBM Final Localization
  19. Fermi GRB 260703A: Global MASTER-Net observations report
  20. GRB 260703A: Fermi GBM Final Localization
  21. GRB 260610B: VLA detection
  22. GRB 260623A: Glowbug gamma-ray detection
  23. GRB 260614B: ATCA Radio Upper Limits
  24. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  25. GRB 260701A: Fermi GBM Final Real-time Localization
  26. Fermi GBM trigger 804552016/260630945 is not a GRB
  27. GRB 260629A: Fermi GBM Final Real-time Localization
  28. Fermi GRB 260628A: Global MASTER-Net observations report
  29. GRB 260628A: Fermi GBM Final Real-time Localization
  30. Konus-Wind detection of GRB 260623B / EP260623a
  31. GRB 260618A: Fermi GBM Observation
  32. MASS-Cube (GRID 2.0) detection of GRB 260616B
  33. GRB 260619A: SVOM/ECLAIRs refined analysis
  34. Fermi GBM trigger 804010507/260624677 is not a GRB
  35. Konus-Wind detection of GRB 260618B
  36. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  37. GRB 260624A: Fermi GBM Final Real-time Localization
  38. GRB 260617A: Glowbug gamma-ray detection of a short burst
  39. IPN triangulation of GRB 260605A
  40. GRB 260623A: Fermi GBM Final Real-time Localization
  41. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  42. GRB 260614B: EP-FXT follow-up observation
  43. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  44. GRB 260619A: NOT optical observations
  45. GRB 260618B: LCO optical observations
  46. EP260618a: JinShan optical observations
  47. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  48. GRB 260618B: Fermi GBM Observation
  49. GRB 260619A: TRT optical counterpart confirmation
  50. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  51. GRB 260604B: 239Alferov CubeSat detection
  52. GRB 260604A: 239Alferov CubeSat detection
  53. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  54. GRB 260619A: SVOM/VT optical counterpart confirmation
  55. GRB 260618B: SVOM/VT optical candidate
  56. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  57. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  58. Konus-Wind detection of GRB 260617A
  59. GRB 260616B: AstroSat CZTI detection
  60. GRB 260616A: AstroSat CZTI detection
  61. GRB 260616A: SVOM/GRM observation
  62. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  63. GRB 260619A: Kilonova-Catcher optical upper limit
  64. EP260618a: EP-FXT follow-up observation
  65. EP260618a: LCO optical counterpart confirmation
  66. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  67. EP260618a: COLIBRÍ optical counterpart candidate
  68. GRB 260616A: NuSTAR detection of prompt emission
  69. GRB 260614B: NuSTAR detection of prompt emission
  70. GRB 260619A: SVOM possible detection of a faint burst
  71. GRB 260618B: Fermi-LAT detection
  72. IPN triangulation of GRB 260617A (short)
  73. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  74. GRB 260616A: Insight-HXMT detection
  75. GRB 260618B: Fermi GBM Final Real-time Localization
  76. EP260618a: EP-WXT detection of an X-ray transient
  77. GRB 260610B: AbAO optical observations
  78. EP260616a/GRB 260616B: EP-FXT follow-up observation
  79. GRB 260506B: cubesat Avion detection
  80. GRB 260616C: GECAM-B observation of a burst
  81. GRB 260618A: Fermi GBM Final Real-time Localization
  82. GRB 260617A: Fermi GBM Detection
  83. GRB 260616A: Fermi GBM Observation
  84. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  85. GRB 260617A: Fermi GBM Final Real-time Localization
  86. Konus-Wind detection of GRB 260616B/EP260616a
  87. Konus-Wind detection of GRB 260616A
  88. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  89. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  90. GRB 260616A: GECAM-B observation
  91. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  92. GRB 260429A: cubesat Avion detection
  93. GRB260616C: MAXI/GSC detection
  94. GRB 260616A: Fermi-LAT detection
  95. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  96. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  97. GRB 260614A: AstroSat CZTI detection
  98. EP260616a: EP-WXT detection of a fast X-ray transient
  99. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  100. GRB 260616B: Fermi GBM Detection

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