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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"

11528 results found.

  1. Fermi GRB 251214A: Global MASTER-Net observations report
  2. GRB 251214A: Fermi GBM Final Real-time Localization
  3. GRB 251211B: AstroSat CZTI detection
  4. GRB 251209A: NuSTAR detection of prompt emission
  5. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  6. Fermi GRB 251211B: Global MASTER-Net observations report
  7. GRB 251211B: Fermi GBM Final Real-time Localization
  8. GRB 251211A: Fermi GBM Final Real-time Localization
  9. GRB 251209A: Fermi GBM observation
  10. GRB 251209A: AstroSat CZTI detection
  11. IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
  12. GRB 251208A: AstroSat CZTI detection
  13. Fermi GBM Sub-Threshold Detection of GRB 251205A
  14. GRB 251208A: Glowbug gamma-ray detection
  15. GRB 251208B: COLIBRÍ optical upper limits
  16. GRB 251208C: GECAM-B observation of a short burst
  17. GRB 251208A: GECAM-B observation of a short burst
  18. Fermi GRB 251209A: Global MASTER-Net observations report
  19. Fermi GRB 251208C: Global MASTER-Net observations report
  20. GRB 251208B: Swift-XRT afterglow detection
  21. GRB 251209A: Fermi GBM Final Real-time Localization
  22. GRB 251208B: Fermi GBM Observation
  23. GRB 251208B: GROWTH-India Telescope optical upper limits
  24. GRB 251208A: SVOM/GRM observation of a short burst
  25. GRB 251208C: SVOM/GRM observation of a short burst
  26. GRB 251208B: Swift ToO observations
  27. GRB 251208B: Fermi-LAT detection
  28. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  29. GRB 251208C: Fermi GBM Final Real-time Localization
  30. GRB 251208B: Fermi GBM Final Real-time Localization
  31. GRB 251208A: Fermi GBM Final Real-time Localization
  32. Konus-Wind detection of GRB 251118A
  33. GRB 251126B: Fermi GBM Final Localization
  34. GRB 251203A: Insight-HXMT/HE detection
  35. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  36. GRB 251202A: SVOM/GRM observation
  37. GRB 251203A: GECAM-B observation of a burst
  38. GRB 251203A: SVOM/GRM observation
  39. GRB 251201B: SALT spectroscopic redshift z = 1.599
  40. GRB 251203A: AstroSat CZTI detection
  41. Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
  42. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  43. GRB 251201B: Insight-HXMT/HE detection
  44. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  45. GRB 251203A: Fermi GBM Final Real-time Localization
  46. EP251202a / GRB251202A: AstroSat CZTI detection
  47. GRB 251202A / EP251202a: SVOM/VT optical observation
  48. GRB 251201B: Fermi GBM Observation
  49. EP251202a/GRB 251202A: KAIT optical observations
  50. Fermi GRB 251202B: Global MASTER-Net observations report
  51. GRB 251202B: Fermi GBM Final Real-time Localization
  52. GRB 251202A: Fermi GBM Observation
  53. GRB 251201B: Kilonova-Catcher optical afterglow detection
  54. GRB 251130B: Glowbug gamma-ray detection
  55. GRB 251201B: GECAM-B observation of a long burst
  56. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  57. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  58. GRB 251202A: GOTO optical afterglow detection
  59. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  60. Fermi GRB 251202A: Global MASTER-Net observations report
  61. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  62. GRB 251202A: Fermi GBM Final Real-time Localization
  63. GRB 251201B: SVOM/VT optical fading
  64. Swift GRB 251201B : MASTER optical counterpart detection
  65. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  66. GRB 251130B: AstroSat CZTI detection
  67. GRB 251201B: Fermi GBM Final Real-time Localization
  68. Fermi GRB 251130B: Global MASTER-Net observations report
  69. GRB 251127A: SVOM/GRM observation
  70. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 251130B: Fermi GBM Final Localization Correction
  72. GRB 251130B: Fermi GBM Final Real-time Localization
  73. GRB 251130A: Fermi GBM Final Real-time Localization
  74. GRB 251128A: AstroSat CZTI detection
  75. GRB 251128A: GECAM-B detection
  76. GRB 251128A: SVOM/GRM observation of a long burst
  77. GRB 251128A: Insight-HXMT/HE detection
  78. GRB 251128A: Fermi GBM Observation
  79. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  80. Fermi GRB 251128A: Global MASTER-Net observations report
  81. GRB 251127A: Glowbug gamma-ray detection
  82. GRB 251128A: Fermi GBM Final Real-time Localization
  83. GRB 251125B: GECAM-B detection
  84. Fermi GRB 251127A: Global MASTER-Net observations report
  85. GRB 251127A: Fermi GBM Final Real-time Localization
  86. GRB 251121A: Fermi GBM Observation
  87. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  88. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  89. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  90. Fermi GRB 251125B: Global MASTER-Net observations report
  91. GRB 251125B: Fermi GBM Final Real-time Localization
  92. Fermi GRB 251125A: Global MASTER-Net observations report
  93. GRB 251125A: Fermi GBM Final Real-time Localization
  94. GRB 251124A: Fermi GBM Localization by automated pipeline
  95. GRB 251122B: Fermi GBM Final Localization
  96. Fermi GRB 251124a: Global MASTER-Net observations report
  97. GRB 251124a: Fermi GBM Final Localization
  98. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  99. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  100. GRB 251115A: Fermi GBM Observation

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