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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"

39064 results found.

  1. GRB 260706A: SVOM/VT optical upper limits
  2. EP260707a (by EP-FXT): NOT optical upper limit
  3. EP260707a: TRT optical upper limit
  4. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  5. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  6. GRB 260705C: Glowbug gamma-ray detection of a short burst
  7. GRB 260706A: SVOM/ECLAIRs refined analysis
  8. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  9. GRB 260706A: SVOM/GRM observation
  10. GRB 260706A: REM optical/NIR observations
  11. IceCube-260704A: No candidates from the Zwicky Transient Facility
  12. GRB 260706A: LCO optical upper limit
  13. GRB 260706A: EP-FXT follow-up observation
  14. GRB 260707A: Fermi GBM Final Real-time Localization
  15. GRB 260706A: Fermi GBM Observation
  16. IPN triangulation of GRB 260627A
  17. GRB 260705A: SVOM/ECLAIRs refined analysis
  18. GRB 260706A: SVOM detection of a burst
  19. GRB 260706A: Fermi GBM Final Real-time Localization
  20. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  21. GRB 260705A: LCO optical upper limits
  22. GRB 260704A: NOT optical upper limits
  23. GRB 260705C: Fermi GBM Final Localization
  24. GRB 260705B: Fermi GBM Final Real-time Localization
  25. Fermi GBM Sub-Threshold Detection of GRB 260705A
  26. GRB 260705A: SVOM detection of a burst
  27. GRB 260704A: EP-FXT follow-up observation
  28. GRB 260629A: SVOM/GRM observation of a short burst
  29. GRB 260629A: GECAM-A observation of a short burst
  30. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  31. GRB 260629A: AstroSat CZTI detection
  32. GRB 260704A: SVOM detection of a possible GRB
  33. GRB 260703B: Fermi GBM Final Localization
  34. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  35. Fermi trigger No 804738310: Global MASTER-Net observations report
  36. Fermi GRB 260703A: Global MASTER-Net observations report
  37. GRB 260703A: Fermi GBM Final Localization
  38. GRB 260610B: VLA detection
  39. GRB 260623A: Glowbug gamma-ray detection
  40. GRB 260614B: ATCA Radio Upper Limits
  41. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  42. Fermi trigger No 804552016: Global MASTER-Net observations report
  43. GRB 260701A: Fermi GBM Final Real-time Localization
  44. Fermi GBM trigger 804552016/260630945 is not a GRB
  45. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  46. GRB 260629A: Fermi GBM Final Real-time Localization
  47. Fermi GRB 260628A: Global MASTER-Net observations report
  48. GRB 260628A: Fermi GBM Final Real-time Localization
  49. EP260626a: COLIBRÍ optical upper limit
  50. Konus-Wind detection of GRB 260623B / EP260623a
  51. GRB 260618A: Fermi GBM Observation
  52. MASS-Cube (GRID 2.0) detection of GRB 260616B
  53. GRB 260619A: SVOM/ECLAIRs refined analysis
  54. Fermi GBM trigger 804010507/260624677 is not a GRB
  55. Konus-Wind detection of GRB 260618B
  56. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  57. GRB 260624A: Fermi GBM Final Real-time Localization
  58. GRB 260617A: Glowbug gamma-ray detection of a short burst
  59. IPN triangulation of GRB 260605A
  60. GRB 260623A: Fermi GBM Final Real-time Localization
  61. EP260623a: TRT optical observations
  62. EP260623a: REM optical/NIR afterglow detection
  63. EP 260623a: COLIBRÍ optical observations
  64. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  65. GRB 260614B: EP-FXT follow-up observation
  66. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  68. GRB 260619A: NOT optical observations
  69. GRB 260618B: LCO optical observations
  70. EP260618a: JinShan optical observations
  71. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  72. GRB 260618B: Fermi GBM Observation
  73. GRB 260619A: TRT optical counterpart confirmation
  74. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  75. GRB 260604B: 239Alferov CubeSat detection
  76. GRB 260604A: 239Alferov CubeSat detection
  77. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  78. GRB 260619A: SVOM/VT optical counterpart confirmation
  79. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  80. GRB 260618B: SVOM/VT optical candidate
  81. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  82. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  83. Konus-Wind detection of GRB 260617A
  84. GRB 260616B: AstroSat CZTI detection
  85. GRB 260616A: AstroSat CZTI detection
  86. GRB 260616A: SVOM/GRM observation
  87. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  88. GRB 260619A: Kilonova-Catcher optical upper limit
  89. EP260618a: EP-FXT follow-up observation
  90. EP260618a: LCO optical counterpart confirmation
  91. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  92. EP260618a: COLIBRÍ optical counterpart candidate
  93. GRB 260616A: NuSTAR detection of prompt emission
  94. GRB 260614B: NuSTAR detection of prompt emission
  95. GRB 260619A: SVOM possible detection of a faint burst
  96. GRB 260618B: Fermi-LAT detection
  97. IPN triangulation of GRB 260617A (short)
  98. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  99. GRB 260616A: Insight-HXMT detection
  100. GRB 260618B: Fermi GBM Final Real-time Localization

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