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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"

4253 results found.

  1. Swift GRB 220118A: Global MASTER-Net observations report
  2. GRB 220118A: Swift detection of a burst with an optical counterpart
  3. GECAM observations of a series of bursts from SGR J1935+2154
  4. Fermi trigger No 663966693: Global MASTER-Net observations report
  5. GECAM observations of a series of bursts from SGR J1935+2154
  6. Fermi-GBM Observations of Recent Bursting Activity from SGR J1935+2154
  7. AGILE observations of a burst from SGR 1935+2154
  8. GECAM observations of a series of bursts from SGR J1935+2154
  9. Fermi Gamma-ray Burst Monitor trigger 220111325/663580106 is not a GRB
  10. GECAM observations of a series of bursts from SGR J1935+2154
  11. GECAM observation of a burst from SGR J1555.2-5402
  12. GECAM detection of a short burst from SGR 1935+2154
  13. Fermi trigger No 663129379: Global MASTER-Net observations report
  14. GECAM observations of a series of bursts from SGR J1935+2154
  15. GRB 220101A: iTelescope optical observations
  16. GRB 220104A：GECAM detection
  17. GRB 211229B: Fermi GBM observation
  18. IPN triangulation of GRB 211219A
  19. GRB 211231A: GECAM detection
  20. GRB 211229B: AGILE detection
  21. GRB 211229A: Fermi GBM observation
  22. GRB 211229B: GECAM detection
  23. Fermi GRB 211229B: Global MASTER-Net observations report
  24. GRB 211229B: Fermi GBM Final Real-time Localization
  25. GRB 211229A: Swift/BAT-GUANO arcminute localization
  26. GRB 211229A: GECAM detection
  27. Fermi GRB 211229A: Global MASTER-Net observations report
  28. GRB 211229A: Fermi GBM Final Real-time Localization
  29. Konus-Wind detection of the intermediate flare from SGR 1935+2154
  30. Fermi GRB 211225C: Global MASTER-Net observations report
  31. GRB 211225A/MAXI J0827-071: MAXI/GSC detection
  32. Fermi trigger No 662084433: Global MASTER-Net observations report
  33. GRB 211106A: Third HST Observation
  34. GRB 211211A: observations with the 3.6m Devasthal Optical Telescope
  35. AGILE observations of a bright burst from SGR 1935+2154
  36. GRB 211223C: Swift detection of a burst
  37. GRB 211223A: GECAM detection
  38. GRB 211218A: MITSuME Akeno optical upper limits
  39. GRB 211218A, MAXI J0909-041: MAXI/GSC detection
  40. MAXI GRB211218.04: Global MASTER-Net observations report
  41. GRB 211217A: GECAM detection
  42. GRB 211216B: GECAM detection
  43. GRB 211216A: GECAM detection
  44. Fermi GRB 211216A: Global MASTER-Net observations report
  45. GRB 211211B: GECAM detection
  46. Fermi GRB 211211B: Global MASTER-Net observations report
  47. Fermi trigger No 660736561: Global MASTER-Net observations report
  48. IPN triangulation of GRB 211204C
  49. GRB 211204C: GECAM detection
  50. Fermi GRB 211204B: Global MASTER-Net observations report
  51. GRB 211124A: Fermi GBM Observation
  52. GRB 211201A: GECAM detection
  53. GRB 211106A: GECAM detection
  54. GRB 211129A: Swift-BAT refined analysis
  55. IceCube-Cascade 211128A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 211129A: Fermi GBM observation
  57. Swift GRB 211129A: Global MASTER-Net observations report
  58. GRB 211129A: Nanshan/NEXT optical upper limit
  59. GRB 211129A: MITSuME Akeno optical upper limits
  60. IceCube Alert 211125.27: Global MASTER-Net observations report
  61. IPN triangulation of GRB 211124A (short)
  62. GRB 211124A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  63. Fermi trigger No 659106591: Global MASTER-Net observations report
  64. GRB 211120A: GECAM detection
  65. Fermi trigger No 658971499: Global MASTER-Net observations report
  66. Fermi trigger No 658755664: Global MASTER-Net observations report
  67. GRB 211115A: MAXI/GSC detection
  68. Fermi GRB 211112A: Global MASTER-Net observations report
  69. GRB 211110A: GECAM detection
  70. Fermi trigger No 658214822: Global MASTER-Net observations report
  71. GRB 211107A: GECAM detection
  72. Fermi GRB 211109B: Global MASTER-Net observations report
  73. GRB 211109C: GECAM detection
  74. GRB 211105A: GECAM detection
  75. GRB 211023A: continued 1.3m DFOT Optical Observations and possible jet break
  76. GRB 211024A: MITSuME Akeno optical observation
  77. GRB 211102B: GECAM detection
  78. Fermi GRB 211102A: Global MASTER-Net observations report
  79. GRB 211023B: MITSuME Akeno optical upper limits
  80. Fermi GRB 211031A: Global MASTER-Net observations report
  81. IPN triangulation of GRB 211022A
  82. GRB 211023A: Terskol optical observations
  83. GECAM detection of a short burst probably from SGR J1555.2-5402
  84. GRB 211024A: GECAM detection
  85. GRB 211022A: GECAM detection
  86. Fermi trigger No 656506979: Global MASTER-Net observations report
  87. GRB 211018A: Detection by GRBAlpha
  88. Fermi trigger No 656288898: Global MASTER-Net observations report
  89. Fermi trigger No 655673024: Global MASTER-Net observations report
  90. Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
  91. Fermi trigger No 655646385: Global MASTER-Net observations report
  92. Fermi Gamma-ray Burst Monitor trigger 211008665/655401471 is not a GRB
  93. Fermi trigger No 655401471: Global MASTER-Net observations report
  94. GECAM observation of a burst from SGR J1555.2-5402
  95. SGR 1935+2154: Swift/BAT-GUANO detection and arcminute localization
  96. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  97. GRB 210927B: GECAM detection
  98. GRB 210927A: GIT optical follow-up of ZTF21acdwctm.
  99. Fermi GRB 210929B: Global MASTER-Net observations report
  100. GRB 210929B: Fermi GBM Final Real-time Localization

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