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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. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  2. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  3. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  4. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  5. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  6. GRB 230111A: Fermi GBM Observation
  7. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  8. Fermi GRB 230112A: Global MASTER-Net observations report
  9. IceCube Alert 230112.28: Global MASTER-Net observations report
  10. GRB 230112A: Fermi GBM Final Real-time Localization
  11. GRB 230111A: MAXI/GSC detection
  12. GRB 230111A: Fermi GBM Final Real-time Localization
  13. GRB 230106: AstroSat LAXPC detection
  14. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  15. Fermi trigger No 695057654: Global MASTER-Net observations report
  16. IceCube-221223A: JCMT/SCUBA2 observations
  17. GRB 230102A: Fermi GBM Observation
  18. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  19. GRB 221231A: 3.6m DOT optical upper limit
  20. GRB 230104A: AGILE/MCAL detection of a burst
  21. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  22. GRB 221231A: Fermi GBM Observation
  23. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  24. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  25. GRB 230102A: Detection by GRBAlpha
  26. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  27. GRB 230101A: AstroSat CZTI detection
  28. Fermi trigger No 694259491: Global MASTER-Net observations report
  29. GRB 221231A: Swift-XRT afterglow detection
  30. GRB 230102A: AGILE/MCAL detection
  31. GRB 230102A: Fermi GBM Final Real-time Localization
  32. GRB 221231A: AKO Upper Limit
  33. GRB 221231A: Swift-XRT observations
  34. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  35. GRB 221231A: Swift ToO observations
  36. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  37. Fermi trigger No 694232203: Global MASTER-Net observations report
  38. GRB 230101A: Fermi GBM Final Real-time Localization
  39. GRB 221231A: Fermi GBM Final Real-time Localization
  40. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  41. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  42. Fermi-LAT gamma-ray observations of IceCube-221229A
  43. GRB 221226A: Fermi GBM detection
  44. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  45. IPN triangulation of GRB 221226A
  46. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  47. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  48. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  49. GRB 221226B: LCOGT Optical Upper Limits
  50. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  51. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 221228A: Fermi GBM Final Real-time Localization
  53. GRB 221226B Swift-BAT refined analysis
  54. GRB 221226B: Swift-UVOT Detection
  55. GRB 221226A: AGILE detection
  56. GRB 221226B: Fermi GBM Observation
  57. GRB 221226B: Swift-XRT refined Analysis
  58. GRB 221226B: VLT/X-shooter redshift and host galaxy
  59. GRB 221226B: Enhanced Swift-XRT position
  60. GRB 221226B: Swift detection of a burst
  61. GRB 221226B: Fermi GBM Final Real-time Localization
  62. Swift GRB221226.95: Global MASTER-Net observations report
  63. Fermi GRB 221226A: Global MASTER-Net observations report
  64. GRB 221226A: Fermi GBM Final Real-time Localization
  65. Fermi-LAT gamma-ray observations of IceCube-221224A
  66. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  67. IceCube-221223A: BOOTES-4/MET Optical Observations
  68. Fermi-LAT gamma-ray observations of IceCube-221223A
  69. Fermi GRB 221223A: Global MASTER-Net observations report
  70. IceCube Alert 221224.04: Global MASTER-Net observations report
  71. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  72. GRB 221223A: Fermi GBM Final Real-time Localization
  73. IceCube Alert 221223.32: Global MASTER-Net observations report
  74. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 221221A: AGILE detection
  76. Fermi GRB 221221A: Global MASTER-Net observations report
  77. GRB 221221A: Fermi GBM Final Real-time Localization
  78. GRB 221218A: 3.6m DOT optical upper limit
  79. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  80. GRB 221216A: Detection by VZLUSAT-2
  81. GRB 221218A: MITSuME Akeno optical upper limits
  82. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  83. GRB 221218A: KAIT Optical Upper Limit
  84. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  85. GRB 221215A: Fermi GBM Detection
  86. GRB 221218A: a long GRB detected by INTEGRAL
  87. Integral GRB221218.34: Global MASTER-Net observations report
  88. Fermi-LAT gamma-ray observations of IceCube-221216A
  89. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 221216A: Swift/UVOT Upper Limits
  91. GRB 221216A: Fermi GBM observation
  92. GRB 221216A: Swift-XRT refined Analysis
  93. Fermi-LAT gamma-ray observations of IceCube-221210A
  94. IceCube Alert 221216.25: Global MASTER-Net observations report
  95. GRB 221216A: AKO Upper Limit
  96. GRB 221215A: Swift-XRT observations
  97. GRB 221216A: Enhanced Swift-XRT position
  98. Swift GRB 221216A: Global MASTER-Net observations report
  99. GRB 221216A: Zadko observatory - Gingin optical observations
  100. GRB 221216A: Nanshan/NEXT optical upper limits

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