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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"

37549 results found.

  1. GRB 260706A: SVOM/GRM observation
  2. GRB 260706A: REM optical/NIR observations
  3. GRB 260706A: LCO optical upper limit
  4. GRB 260706A: EP-FXT follow-up observation
  5. GRB 260707A: Fermi GBM Final Real-time Localization
  6. GRB 260706A: Fermi GBM Observation
  7. IPN triangulation of GRB 260627A
  8. GRB 260705A: SVOM/ECLAIRs refined analysis
  9. GRB 260706A: SVOM detection of a burst
  10. GRB 260706A: Fermi GBM Final Real-time Localization
  11. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  12. GRB 260705A: LCO optical upper limits
  13. GRB 260704A: NOT optical upper limits
  14. GRB 260705C: Fermi GBM Final Localization
  15. GRB 260705B: Fermi GBM Final Real-time Localization
  16. Fermi GBM Sub-Threshold Detection of GRB 260705A
  17. GRB 260705A: SVOM detection of a burst
  18. GRB 260704A: EP-FXT follow-up observation
  19. GRB 260629A: SVOM/GRM observation of a short burst
  20. GRB 260629A: GECAM-A observation of a short burst
  21. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 260629A: AstroSat CZTI detection
  23. GRB 260704A: SVOM detection of a possible GRB
  24. GRB 260703B: Fermi GBM Final Localization
  25. Fermi trigger No 804738310: Global MASTER-Net observations report
  26. Fermi GRB 260703A: Global MASTER-Net observations report
  27. GRB 260703A: Fermi GBM Final Localization
  28. GRB 260610B: VLA detection
  29. GRB 260623A: Glowbug gamma-ray detection
  30. GRB 260614B: ATCA Radio Upper Limits
  31. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  32. Fermi trigger No 804552016: Global MASTER-Net observations report
  33. GRB 260701A: Fermi GBM Final Real-time Localization
  34. Fermi GBM trigger 804552016/260630945 is not a GRB
  35. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  36. GRB 260629A: Fermi GBM Final Real-time Localization
  37. Fermi GRB 260628A: Global MASTER-Net observations report
  38. GRB 260628A: Fermi GBM Final Real-time Localization
  39. Konus-Wind detection of GRB 260623B / EP260623a
  40. GRB 260618A: Fermi GBM Observation
  41. MASS-Cube (GRID 2.0) detection of GRB 260616B
  42. GRB 260619A: SVOM/ECLAIRs refined analysis
  43. Fermi GBM trigger 804010507/260624677 is not a GRB
  44. Konus-Wind detection of GRB 260618B
  45. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  46. GRB 260624A: Fermi GBM Final Real-time Localization
  47. GRB 260617A: Glowbug gamma-ray detection of a short burst
  48. IPN triangulation of GRB 260605A
  49. GRB 260623A: Fermi GBM Final Real-time Localization
  50. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  51. GRB 260614B: EP-FXT follow-up observation
  52. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  53. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  54. GRB 260619A: NOT optical observations
  55. GRB 260618B: LCO optical observations
  56. EP260618a: JinShan optical observations
  57. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  58. GRB 260618B: Fermi GBM Observation
  59. GRB 260619A: TRT optical counterpart confirmation
  60. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  61. GRB 260604B: 239Alferov CubeSat detection
  62. GRB 260604A: 239Alferov CubeSat detection
  63. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  64. GRB 260619A: SVOM/VT optical counterpart confirmation
  65. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  66. GRB 260618B: SVOM/VT optical candidate
  67. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  68. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  69. Konus-Wind detection of GRB 260617A
  70. GRB 260616B: AstroSat CZTI detection
  71. GRB 260616A: AstroSat CZTI detection
  72. GRB 260616A: SVOM/GRM observation
  73. EP260618a: OHP/T193 optical observations
  74. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  75. GRB 260619A: Kilonova-Catcher optical upper limit
  76. EP260618a: EP-FXT follow-up observation
  77. EP260618a: LCO optical counterpart confirmation
  78. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  79. EP260618a: COLIBRÍ optical counterpart candidate
  80. GRB 260616A: NuSTAR detection of prompt emission
  81. GRB 260614B: NuSTAR detection of prompt emission
  82. GRB 260619A: SVOM possible detection of a faint burst
  83. GRB 260618B: Fermi-LAT detection
  84. IPN triangulation of GRB 260617A (short)
  85. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  86. GRB 260616A: Insight-HXMT detection
  87. GRB 260618B: Fermi GBM Final Real-time Localization
  88. EP260618a: EP-WXT detection of an X-ray transient
  89. GRB 260610B: AbAO optical observations
  90. EP260616a/GRB 260616B: EP-FXT follow-up observation
  91. GRB 260506B: cubesat Avion detection
  92. GRB 260616C: GECAM-B observation of a burst
  93. GRB 260618A: Fermi GBM Final Real-time Localization
  94. GRB 260617A: Fermi GBM Detection
  95. GRB 260616A: Fermi GBM Observation
  96. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  97. GRB 260617A: Fermi GBM Final Real-time Localization
  98. Konus-Wind detection of GRB 260616B/EP260616a
  99. Konus-Wind detection of GRB 260616A
  100. GRB 260616B: CALET Gamma-Ray Burst Monitor detection

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