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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 Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  2. GRB 221231A: 3.6m DOT optical upper limit
  3. GRB 230104A: AGILE/MCAL detection of a burst
  4. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  5. GRB 221231A: Fermi GBM Observation
  6. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  7. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  8. GRB 230102A: Detection by GRBAlpha
  9. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  10. GRB 230101A: AstroSat CZTI detection
  11. Fermi trigger No 694259491: Global MASTER-Net observations report
  12. GRB 221231A: Swift-XRT afterglow detection
  13. GRB 230102A: AGILE/MCAL detection
  14. GRB 230102A: Fermi GBM Final Real-time Localization
  15. GRB 221231A: AKO Upper Limit
  16. GRB 221231A: Swift-XRT observations
  17. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  18. GRB 221231A: Swift ToO observations
  19. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  20. Fermi trigger No 694232203: Global MASTER-Net observations report
  21. GRB 230101A: Fermi GBM Final Real-time Localization
  22. GRB 221231A: Fermi GBM Final Real-time Localization
  23. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  25. Fermi-LAT gamma-ray observations of IceCube-221229A
  26. GRB 221226A: Fermi GBM detection
  27. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  28. IPN triangulation of GRB 221226A
  29. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  31. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  32. GRB 221226B: LCOGT Optical Upper Limits
  33. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  34. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  35. GRB 221228A: Fermi GBM Final Real-time Localization
  36. GRB 221226B Swift-BAT refined analysis
  37. GRB 221226B: Swift-UVOT Detection
  38. GRB 221226A: AGILE detection
  39. GRB 221226B: Fermi GBM Observation
  40. GRB 221226B: Swift-XRT refined Analysis
  41. GRB 221226B: VLT/X-shooter redshift and host galaxy
  42. GRB 221226B: Enhanced Swift-XRT position
  43. GRB 221226B: Swift detection of a burst
  44. GRB 221226B: Fermi GBM Final Real-time Localization
  45. Swift GRB221226.95: Global MASTER-Net observations report
  46. Fermi GRB 221226A: Global MASTER-Net observations report
  47. GRB 221226A: Fermi GBM Final Real-time Localization
  48. Fermi-LAT gamma-ray observations of IceCube-221224A
  49. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  50. IceCube-221223A: BOOTES-4/MET Optical Observations
  51. Fermi-LAT gamma-ray observations of IceCube-221223A
  52. Fermi GRB 221223A: Global MASTER-Net observations report
  53. IceCube Alert 221224.04: Global MASTER-Net observations report
  54. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 221223A: Fermi GBM Final Real-time Localization
  56. IceCube Alert 221223.32: Global MASTER-Net observations report
  57. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  58. GRB 221221A: AGILE detection
  59. Fermi GRB 221221A: Global MASTER-Net observations report
  60. GRB 221221A: Fermi GBM Final Real-time Localization
  61. GRB 221218A: 3.6m DOT optical upper limit
  62. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  63. GRB 221216A: Detection by VZLUSAT-2
  64. GRB 221218A: MITSuME Akeno optical upper limits
  65. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  66. GRB 221218A: KAIT Optical Upper Limit
  67. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  68. GRB 221215A: Fermi GBM Detection
  69. GRB 221218A: a long GRB detected by INTEGRAL
  70. Integral GRB221218.34: Global MASTER-Net observations report
  71. Fermi-LAT gamma-ray observations of IceCube-221216A
  72. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 221216A: Swift/UVOT Upper Limits
  74. GRB 221216A: Fermi GBM observation
  75. GRB 221216A: Swift-XRT refined Analysis
  76. Fermi-LAT gamma-ray observations of IceCube-221210A
  77. IceCube Alert 221216.25: Global MASTER-Net observations report
  78. GRB 221216A: AKO Upper Limit
  79. GRB 221215A: Swift-XRT observations
  80. GRB 221216A: Enhanced Swift-XRT position
  81. Swift GRB 221216A: Global MASTER-Net observations report
  82. GRB 221216A: Zadko observatory - Gingin optical observations
  83. GRB 221216A: Nanshan/NEXT optical upper limits
  84. GRB 221216A: Swift detection of a burst
  85. GRB 221216A: Fermi GBM Final Real-time Localization
  86. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  87. Fermi trigger No 692760884: Global MASTER-Net observations report
  88. GRB 221215A: Swift ToO observations
  89. GRB 221215A: Swift/BAT-GUANO arcminute localization
  90. Konus-Wind detection of GRB 221209A
  91. Fermi GRB 221215B: Global MASTER-Net observations report
  92. IPN triangulation of GRB 221209A (long)
  93. GRB 221215B: Fermi GBM Final Real-time Localization
  94. Fermi Gamma-ray Burst Monitor trigger 692760884/221215066 is not a GRB
  95. Swift GRB221215.15: Global MASTER-Net observations report
  96. Fermi trigger No 692713692: Global MASTER-Net observations report
  97. GRB 221215A: Fermi GBM Final Real-time Localization
  98. Swift Trigger 1144538 is not a GRB
  99. Fermi Gamma-ray Burst Monitor triggers 692721536/221214610 and 692713692/221214520 are not GRBs
  100. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13

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