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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"

11565 results found.

  1. Fermi GBM Sub-Threshold Detection of GRB 260204A
  2. GRB 260204B: Fermi GBM Final Real-time Localization
  3. GRB 260131A/B: OHP/T193 optical observations
  4. GRB 260131A: KAIT optical observations
  5. GRB 260131A: FTW optical and NIR observations
  6. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  7. GRID detection of GRB 260131A/B
  8. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  9. GRB 260130A: Insight-HXMT/HE detection
  10. GRB 260130A: GECAM-B observation of a short burst
  11. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  12. GRB 260131A/B: EP/FXT X-ray afterglow detection
  13. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  14. GRB 260127B: Insight-HXMT/HE detection
  15. GRB 260127B: GECAM-B observation of a short burst
  16. GRB 260127A: GECAM-B observation
  17. GRB 260131A: NOT spectroscopic redshift z = 1.434
  18. Konus-Wind detection of GRB 260128A / EP260128a
  19. GRB 260131A: Insight-HXMT/HE detection
  20. Konus-Wind detection of GRB 260131A/B
  21. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  22. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  23. GRB 260131A/B: Fermi GBM Observation
  24. GRB 260131A: Fermi GBM Final Real-time Localization
  25. GRB 260127B: AstroSat CZTI detection
  26. GRB 260130A: Fermi GBM Detection
  27. GRB 260127B: Fermi GBM Detection
  28. Fermi GRB 260130A: Global MASTER-Net observations report
  29. GRB 260130A: Fermi GBM Final Real-time Localization
  30. Fermi GRB 260129A: Global MASTER-Net observations report
  31. IPN triangulation of GRB 260121A
  32. GRB 260129B: Fermi GBM Final Localization
  33. GRB 260129A: Fermi GBM Final Localization
  34. IPN triangulation of GRB 260127B (short)
  35. GRB 260127B: Swift-XRT observations
  36. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  37. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  38. Fermi GRB 260127A: Global MASTER-Net observations report
  39. GRB 260127A: Fermi GBM Observation
  40. GRB 260127A: COLIBRÍ optical observations
  41. GRB 260127A: NOT optical observations
  42. GRB 260127B: Swift ToO observations
  43. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  44. GRB 260127B: GOTO candidate optical counterpart
  45. GRB 260127A: SVOM/C-GFT optical observations
  46. Fermi GRB 260127B: Global MASTER-Net observations report
  47. GRB 260127B: Fermi GBM Final Real-time Localization
  48. GRB 260127A: LCO optical afterglow discovery
  49. GRB 260127A: Fermi GBM Final Real-time Localization
  50. GRB 260125A: Swift-XRT observations
  51. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  52. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  53. Konus-Wind detection of GRB 260120B
  54. GRB 260125A: Swift ToO observations
  55. GRB 260125A: GOTO candidate optical counterpart
  56. Fermi GRB 260125B: Global MASTER-Net observations report
  57. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  58. GRB 260125B: Fermi GBM Final Real-time Localization
  59. GRB 260125A: Fermi GBM Final Real-time Localization
  60. GRB 260114A: SVOM/VT optical upper limits
  61. GRB 260120A: AstroSat CZTI detection
  62. GRB 260120B: SVOM/GRM observation
  63. GRB 260120A: GECAM-B observation
  64. GRB 260120B: AstroSat CZTI detection
  65. GRB 260114A: Insight-HXMT/HE detection
  66. GRB 260122A: Fermi GBM Final Real-time Localization
  67. Fermi GRB 260120C: Global MASTER-Net observations report
  68. GRB 260120B: Fermi GBM Observation
  69. GRB 260120B: COLIBRÍ optical upper limits
  70. GRB 260120B: SVOM/C-GFT optical counterpart detection
  71. GRB 260120C: Fermi GBM Final Real-time Localization
  72. GRB 260101A: 239Alferov CubeSat detection
  73. GRB 260120B: Fermi GBM Final Real-time Localization
  74. Fermi trigger No 790601190: Global MASTER-Net observations report
  75. Fermi trigger No 790570272: Global MASTER-Net observations report
  76. GRB 251202A: further radio observations with the VLA
  77. GRB 260120A: Fermi GBM Final Real-time Localization
  78. GRB 260115A: AstroSat CZTI detection
  79. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  80. GRB 260115A: GECAM-B observation
  81. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  82. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  83. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  84. Fermi GRB 260115A: Global MASTER-Net observations report
  85. GRB 260115A: Fermi GBM Final Real-time Localization
  86. GRB260114A: STEP/T80S optical limits
  87. GRB 251222A: radio detection with the VLA
  88. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  89. Konus-Wind detection of GRB 260114A
  90. GRB 260114A: 6 GHz VLA observations
  91. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  92. GRB 260114A : MITSuME Akeno optical upper limits
  93. GRB 260114A: COLIBRÍ optical upper limits
  94. GRB 260114A: TNG NIR upper limit
  95. GRB 260114A: NOT optical observations
  96. GRB 260114A: SVOM/GRM observation of a short burst
  97. GRB 260114A: GECAM-B observation of a short burst
  98. GRB 260114A: Mondy optical observations
  99. GRB 260114A: Fermi GBM observation
  100. GRB 260112B: GECAM-B observation

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