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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').
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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"

11546 results found.

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

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