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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"

11522 results found.

  1. GRB 211024A: Swift-XRT source 4 is not an afterglow.
  2. Fermi GRB 211027A: Global MASTER-Net observations report
  3. GRB 211024A: Possible afterglow candidate from GIT
  4. GRB 211027A: Fermi GBM Final Real-time Localization
  5. GRB 211024A: Fermi GBM detection
  6. GRB 211018A: Swift-XRT observations
  7. GRB211023A: optical afterglow detection from Konkoly Observatory
  8. GRB 211024A: Swift/BAT-GUANO detection and candidate arcminute localization of a short burst
  9. GRB 211023A: Mondy optical observations
  10. Correction to GCN 30965: GRB 211023A: Fermi GBM detection
  11. IPN Triangulation of GRB 211019A
  12. GRB 211023A: 1.5m OSN optical observation
  13. GRB 211023A: OAJ Bright Afterglow Confirmation
  14. Fermi-LAT Gamma-ray Observations of IceCube-211023A
  15. GRB 211023A: MASTER OT J045237.07+851925.2 - optical counterpart discovery
  16. GRB 211024A: GECAM detection
  17. Fermi GRB 211023A: Global MASTER-Net observations report
  18. GRB 211023A: AGILE detection
  19. GRB 211023A: Fermi GBM detection
  20. Fermi GRB 211024A: Global MASTER-Net observations report
  21. GRB 211024A: Fermi GBM Final Real-time Localization
  22. GRB 211023A: Fermi-LAT detection
  23. GRB 211023A: Fermi GBM Final Real-time Localization
  24. IPN Triangulation of GRB 210927B
  25. GRB 211018A: Swift ToO observations
  26. GRB 211021A: BALROG localization (Fermi Trigger 656506979 / GRB 211021460)
  27. Fermi trigger No 656506979: Global MASTER-Net observations report
  28. Fermi trigger No 656268212: Global MASTER-Net observations report
  29. GRB 211018A: Fermi GBM observation
  30. GRB 211019A: Detection by GRBAlpha
  31. GRB 211018A: Detection by GRBAlpha
  32. Fermi GRB 211019A: Global MASTER-Net observations report
  33. GRB 211018A: Fermi-LAT detection
  34. GRB 211019A: BALROG localization (Fermi Trigger 656315976 / GRB 211019250)
  35. GRB 211019A: Fermi GBM Final Real-time Localization
  36. Fermi trigger No 656288898: Global MASTER-Net observations report
  37. Fermi trigger No 655673024: Global MASTER-Net observations report
  38. Fermi trigger No 655646385: Global MASTER-Net observations report
  39. Fermi Gamma-ray Burst Monitor trigger 211008665/655401471 is not a GRB
  40. GRB 211008A: BALROG localization (Fermi Trigger 655401471 / GRB 211008665)
  41. Fermi trigger No 655401471: Global MASTER-Net observations report
  42. GRB 210928A: MeerKAT detection
  43. GECAM observation of a burst from SGR J1555.2-5402
  44. Konus-Wind detection of GRB 210928A
  45. Fermi trigger No 654854799: Global MASTER-Net observations report
  46. GRB 210928A: Kinder SLT-40cm optical limits
  47. SGR 1935+2154: Swift/BAT-GUANO detection and arcminute localization
  48. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  49. GRB 210928A: Fermi GBM observation
  50. GRB 210928A: Fermi-LAT detection
  51. GRB 210927B: GECAM detection
  52. Fermi trigger No 654739449: Global MASTER-Net observations report
  53. Fermi trigger No 654658271: Global MASTER-Net observations report
  54. Fermi GRB 210929B: Global MASTER-Net observations report
  55. GRB 210929B: Fermi GBM Final Real-time Localization
  56. Fermi-LAT Gamma-ray Observations of IceCubeCascade-210926A
  57. GRB 210929A: Fermi GBM Final Real-time Localization
  58. GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
  59. IPN triangulation of GRB 210925B
  60. GRB 210926A: GECAM detection
  61. GRB 210927A: Fermi GBM Final Real-time Localization
  62. GRB 210925A: GECAM detection
  63. GRB 210925A: Fermi GBM Final Real-time Localization
  64. GRB 210924A: Fermi GBM Final Real-time Localization
  65. Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
  66. IceCube-210922A: Upper limits from Fermi-GBM Observations
  67. Fermi-LAT Gamma-ray Observations of IceCube-210922A
  68. GRB 210923A: Fermi GBM Final Real-time Localization
  69. IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 210919B: Fermi GBM Final Real-time Localization
  71. GRB 210917A: Fermi GBM Final Real-time Localization
  72. GRB 210812A is not a compelling example of a lensed GRB
  73. GRB 210909A: Detection by GRBAlpha
  74. AGILE observations of two bright bursts from SGR 1935+2154
  75. Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
  76. Fermi trigger No 653151835: Global MASTER-Net observations report
  77. Fermi trigger No 653124492: Global MASTER-Net observations report
  78. Fermi trigger No 653122278: Global MASTER-Net observations report
  79. GRB 210912B: Fermi GBM Final Real-time Localization
  80. Fermi trigger No 653093506: Global MASTER-Net observations report
  81. Fermi trigger No 653066776: Global MASTER-Net observations report
  82. Fermi trigger No 653084584: Global MASTER-Net observations report
  83. Fermi trigger No 653083551: Global MASTER-Net observations report
  84. Fermi trigger No 653079281: Global MASTER-Net observations report
  85. Fermi trigger No 653066130: Global MASTER-Net observations report
  86. Fermi trigger No 653072474: Global MASTER-Net observations report
  87. Fermi trigger No 653071808: Global MASTER-Net observations report
  88. Fermi trigger No 653054042: Global MASTER-Net observations report
  89. Fermi trigger No 653049776: Global MASTER-Net observations report
  90. Fermi trigger No 653022153: Global MASTER-Net observations report
  91. Fermi trigger No 653031163: Global MASTER-Net observations report
  92. Fermi GBM observation of a bright flare in the direction of SGR 1935+2154
  93. Fermi trigger No 653010039: Global MASTER-Net observations report
  94. IPN triangulation of a bright burst from SGR 1935+2154
  95. Fermi trigger No 652957973: Global MASTER-Net observations report
  96. Fermi trigger No 652944960: Global MASTER-Net observations report
  97. Fermi trigger No 652981861: Global MASTER-Net observations report
  98. Fermi trigger No 652934203: Global MASTER-Net observations report
  99. Fermi trigger No 652927551: Global MASTER-Net observations report
  100. Fermi trigger No 652911693: Global MASTER-Net observations report

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