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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"
  1. GRB 230102A: AGILE/MCAL detection
  2. GRB 230102A: Fermi GBM Final Real-time Localization
  3. GRB 221231A: AKO Upper Limit
  4. GRB 221231A: Swift-XRT observations
  5. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  6. GRB 221231A: Swift ToO observations
  7. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  8. Fermi trigger No 694232203: Global MASTER-Net observations report
  9. GRB 230101A: Fermi GBM Final Real-time Localization
  10. GRB 221231A: Fermi GBM Final Real-time Localization
  11. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  12. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  13. Fermi-LAT gamma-ray observations of IceCube-221229A
  14. GRB 221226A: Fermi GBM detection
  15. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  16. IPN triangulation of GRB 221226A
  17. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  19. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  20. GRB 221226B: LCOGT Optical Upper Limits
  21. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  22. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 221228A: Fermi GBM Final Real-time Localization
  24. GRB 221226B Swift-BAT refined analysis
  25. GRB 221226B: Swift-UVOT Detection
  26. GRB 221226A: AGILE detection
  27. GRB 221226B: Fermi GBM Observation
  28. GRB 221226B: Swift-XRT refined Analysis
  29. GRB 221226B: VLT/X-shooter redshift and host galaxy
  30. GRB 221226B: Enhanced Swift-XRT position
  31. GRB 221226B: Swift detection of a burst
  32. GRB 221226B: Fermi GBM Final Real-time Localization
  33. Swift GRB221226.95: Global MASTER-Net observations report
  34. Fermi GRB 221226A: Global MASTER-Net observations report
  35. GRB 221226A: Fermi GBM Final Real-time Localization
  36. Fermi-LAT gamma-ray observations of IceCube-221224A
  37. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  38. IceCube-221223A: BOOTES-4/MET Optical Observations
  39. Fermi-LAT gamma-ray observations of IceCube-221223A
  40. Fermi GRB 221223A: Global MASTER-Net observations report
  41. IceCube Alert 221224.04: Global MASTER-Net observations report
  42. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 221223A: Fermi GBM Final Real-time Localization
  44. IceCube Alert 221223.32: Global MASTER-Net observations report
  45. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 221221A: AGILE detection
  47. Fermi GRB 221221A: Global MASTER-Net observations report
  48. GRB 221221A: Fermi GBM Final Real-time Localization
  49. GRB 221218A: 3.6m DOT optical upper limit
  50. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  51. GRB 221216A: Detection by VZLUSAT-2
  52. GRB 221218A: MITSuME Akeno optical upper limits
  53. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  54. GRB 221218A: KAIT Optical Upper Limit
  55. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  56. GRB 221215A: Fermi GBM Detection
  57. GRB 221218A: a long GRB detected by INTEGRAL
  58. Integral GRB221218.34: Global MASTER-Net observations report
  59. Fermi-LAT gamma-ray observations of IceCube-221216A
  60. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 221216A: Swift/UVOT Upper Limits
  62. GRB 221216A: Fermi GBM observation
  63. GRB 221216A: Swift-XRT refined Analysis
  64. Fermi-LAT gamma-ray observations of IceCube-221210A
  65. IceCube Alert 221216.25: Global MASTER-Net observations report
  66. GRB 221216A: AKO Upper Limit
  67. GRB 221215A: Swift-XRT observations
  68. GRB 221216A: Enhanced Swift-XRT position
  69. Swift GRB 221216A: Global MASTER-Net observations report
  70. GRB 221216A: Zadko observatory - Gingin optical observations
  71. GRB 221216A: Nanshan/NEXT optical upper limits
  72. GRB 221216A: Swift detection of a burst
  73. GRB 221216A: Fermi GBM Final Real-time Localization
  74. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  75. Fermi trigger No 692760884: Global MASTER-Net observations report
  76. GRB 221215A: Swift ToO observations
  77. GRB 221215A: Swift/BAT-GUANO arcminute localization
  78. Konus-Wind detection of GRB 221209A
  79. Fermi GRB 221215B: Global MASTER-Net observations report
  80. IPN triangulation of GRB 221209A (long)
  81. GRB 221215B: Fermi GBM Final Real-time Localization
  82. Fermi Gamma-ray Burst Monitor trigger 692760884/221215066 is not a GRB
  83. Swift GRB221215.15: Global MASTER-Net observations report
  84. Fermi trigger No 692713692: Global MASTER-Net observations report
  85. GRB 221215A: Fermi GBM Final Real-time Localization
  86. Swift Trigger 1144538 is not a GRB
  87. Fermi Gamma-ray Burst Monitor triggers 692721536/221214610 and 692713692/221214520 are not GRBs
  88. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13
  89. Fermi trigger No 692607435: Global MASTER-Net observations report
  90. GRB 221209A: CALET Gamma-Ray Burst Monitor detection
  91. IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
  92. GRB 221212A: Fermi GBM Final Real-time Localization
  93. Fermi GRB 221211A: Global MASTER-Net observations report
  94. GRB 221208A: AstroSat CZTI detection
  95. GRB 221211A: Fermi GBM Final Real-time Localization
  96. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  97. IceCube Alert 221210.36: Global MASTER-Net observations report
  98. GRB 221009A: MuSCAT3 observations
  99. GRB 221209A: AstroSat CZTI detection
  100. GRB 221210A: Fermi GBM Final Real-time Localization

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