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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. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  2. Fermi-LAT gamma-ray observations of IceCube-221229A
  3. GRB 221226A: Fermi GBM detection
  4. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  5. IPN triangulation of GRB 221226A
  6. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  7. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  8. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  9. GRB 221226B: LCOGT Optical Upper Limits
  10. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  11. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  12. GRB 221228A: Fermi GBM Final Real-time Localization
  13. GRB 221226B Swift-BAT refined analysis
  14. GRB 221226B: Swift-UVOT Detection
  15. GRB 221226A: AGILE detection
  16. GRB 221226B: Fermi GBM Observation
  17. GRB 221226B: Swift-XRT refined Analysis
  18. GRB 221226B: VLT/X-shooter redshift and host galaxy
  19. GRB 221226B: Enhanced Swift-XRT position
  20. GRB 221226B: Swift detection of a burst
  21. GRB 221226B: Fermi GBM Final Real-time Localization
  22. Swift GRB221226.95: Global MASTER-Net observations report
  23. Fermi GRB 221226A: Global MASTER-Net observations report
  24. GRB 221226A: Fermi GBM Final Real-time Localization
  25. Fermi-LAT gamma-ray observations of IceCube-221224A
  26. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  27. IceCube-221223A: BOOTES-4/MET Optical Observations
  28. Fermi-LAT gamma-ray observations of IceCube-221223A
  29. Fermi GRB 221223A: Global MASTER-Net observations report
  30. IceCube Alert 221224.04: Global MASTER-Net observations report
  31. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 221223A: Fermi GBM Final Real-time Localization
  33. IceCube Alert 221223.32: Global MASTER-Net observations report
  34. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  35. GRB 221221A: AGILE detection
  36. Fermi GRB 221221A: Global MASTER-Net observations report
  37. GRB 221221A: Fermi GBM Final Real-time Localization
  38. GRB 221218A: 3.6m DOT optical upper limit
  39. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  40. GRB 221216A: Detection by VZLUSAT-2
  41. GRB 221218A: MITSuME Akeno optical upper limits
  42. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  43. GRB 221218A: KAIT Optical Upper Limit
  44. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  45. GRB 221215A: Fermi GBM Detection
  46. GRB 221218A: a long GRB detected by INTEGRAL
  47. Integral GRB221218.34: Global MASTER-Net observations report
  48. Fermi-LAT gamma-ray observations of IceCube-221216A
  49. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  50. GRB 221216A: Swift/UVOT Upper Limits
  51. GRB 221216A: Fermi GBM observation
  52. GRB 221216A: Swift-XRT refined Analysis
  53. Fermi-LAT gamma-ray observations of IceCube-221210A
  54. IceCube Alert 221216.25: Global MASTER-Net observations report
  55. GRB 221216A: AKO Upper Limit
  56. GRB 221215A: Swift-XRT observations
  57. GRB 221216A: Enhanced Swift-XRT position
  58. Swift GRB 221216A: Global MASTER-Net observations report
  59. GRB 221216A: Zadko observatory - Gingin optical observations
  60. GRB 221216A: Nanshan/NEXT optical upper limits
  61. GRB 221216A: Swift detection of a burst
  62. GRB 221216A: Fermi GBM Final Real-time Localization
  63. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  64. Fermi trigger No 692760884: Global MASTER-Net observations report
  65. GRB 221215A: Swift ToO observations
  66. GRB 221215A: Swift/BAT-GUANO arcminute localization
  67. Konus-Wind detection of GRB 221209A
  68. Fermi GRB 221215B: Global MASTER-Net observations report
  69. IPN triangulation of GRB 221209A (long)
  70. GRB 221215B: Fermi GBM Final Real-time Localization
  71. Fermi Gamma-ray Burst Monitor trigger 692760884/221215066 is not a GRB
  72. Swift GRB221215.15: Global MASTER-Net observations report
  73. Fermi trigger No 692713692: Global MASTER-Net observations report
  74. GRB 221215A: Fermi GBM Final Real-time Localization
  75. Swift Trigger 1144538 is not a GRB
  76. Fermi Gamma-ray Burst Monitor triggers 692721536/221214610 and 692713692/221214520 are not GRBs
  77. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13
  78. Fermi trigger No 692607435: Global MASTER-Net observations report
  79. GRB 221209A: CALET Gamma-Ray Burst Monitor detection
  80. IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 221212A: Fermi GBM Final Real-time Localization
  82. Fermi GRB 221211A: Global MASTER-Net observations report
  83. GRB 221208A: AstroSat CZTI detection
  84. GRB 221211A: Fermi GBM Final Real-time Localization
  85. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  86. IceCube Alert 221210.36: Global MASTER-Net observations report
  87. GRB 221009A: MuSCAT3 observations
  88. GRB 221209A: AstroSat CZTI detection
  89. GRB 221210A: Fermi GBM Final Real-time Localization
  90. GRB 221209B: Fermi GBM Final Real-time Localization
  91. GRB 221209A: Fermi GBM observation
  92. GRB 221203C: AstroSat CZTI detection
  93. GRB 221209A: BALROG localization (Fermi Trigger 692257829 / GRB 221209243)
  94. GRB 221209A: Fermi GBM Final Real-time Localization
  95. GRB 221206B: Fermi GBM observation
  96. GRB 221206B: Swift-XRT observations
  97. GRB 221206B: Detection by GRBAlpha
  98. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  99. GRB 221206B: Swift ToO observations
  100. Swift/BAT trigger #1143281 is not a GRB

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