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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 GRB 221223A: Global MASTER-Net observations report
  2. IceCube Alert 221224.04: Global MASTER-Net observations report
  3. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 221223A: Fermi GBM Final Real-time Localization
  5. IceCube Alert 221223.32: Global MASTER-Net observations report
  6. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  7. GRB 221221A: AGILE detection
  8. Fermi GRB 221221A: Global MASTER-Net observations report
  9. GRB 221221A: Fermi GBM Final Real-time Localization
  10. GRB 221218A: 3.6m DOT optical upper limit
  11. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  12. GRB 221216A: Detection by VZLUSAT-2
  13. GRB 221218A: MITSuME Akeno optical upper limits
  14. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  15. GRB 221218A: KAIT Optical Upper Limit
  16. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  17. GRB 221215A: Fermi GBM Detection
  18. GRB 221218A: a long GRB detected by INTEGRAL
  19. Integral GRB221218.34: Global MASTER-Net observations report
  20. Fermi-LAT gamma-ray observations of IceCube-221216A
  21. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 221216A: Swift/UVOT Upper Limits
  23. GRB 221216A: Fermi GBM observation
  24. GRB 221216A: Swift-XRT refined Analysis
  25. Fermi-LAT gamma-ray observations of IceCube-221210A
  26. IceCube Alert 221216.25: Global MASTER-Net observations report
  27. GRB 221216A: AKO Upper Limit
  28. GRB 221215A: Swift-XRT observations
  29. GRB 221216A: Enhanced Swift-XRT position
  30. Swift GRB 221216A: Global MASTER-Net observations report
  31. GRB 221216A: Zadko observatory - Gingin optical observations
  32. GRB 221216A: Nanshan/NEXT optical upper limits
  33. GRB 221216A: Swift detection of a burst
  34. GRB 221216A: Fermi GBM Final Real-time Localization
  35. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  36. Fermi trigger No 692760884: Global MASTER-Net observations report
  37. GRB 221215A: Swift ToO observations
  38. GRB 221215A: Swift/BAT-GUANO arcminute localization
  39. Konus-Wind detection of GRB 221209A
  40. Fermi GRB 221215B: Global MASTER-Net observations report
  41. IPN triangulation of GRB 221209A (long)
  42. GRB 221215B: Fermi GBM Final Real-time Localization
  43. Fermi Gamma-ray Burst Monitor trigger 692760884/221215066 is not a GRB
  44. Swift GRB221215.15: Global MASTER-Net observations report
  45. Fermi trigger No 692713692: Global MASTER-Net observations report
  46. GRB 221215A: Fermi GBM Final Real-time Localization
  47. Swift Trigger 1144538 is not a GRB
  48. Fermi Gamma-ray Burst Monitor triggers 692721536/221214610 and 692713692/221214520 are not GRBs
  49. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13
  50. Fermi trigger No 692607435: Global MASTER-Net observations report
  51. GRB 221209A: CALET Gamma-Ray Burst Monitor detection
  52. IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 221212A: Fermi GBM Final Real-time Localization
  54. Fermi GRB 221211A: Global MASTER-Net observations report
  55. GRB 221208A: AstroSat CZTI detection
  56. GRB 221211A: Fermi GBM Final Real-time Localization
  57. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  58. IceCube Alert 221210.36: Global MASTER-Net observations report
  59. GRB 221009A: MuSCAT3 observations
  60. GRB 221209A: AstroSat CZTI detection
  61. GRB 221210A: Fermi GBM Final Real-time Localization
  62. GRB 221209B: Fermi GBM Final Real-time Localization
  63. GRB 221209A: Fermi GBM observation
  64. GRB 221203C: AstroSat CZTI detection
  65. GRB 221209A: BALROG localization (Fermi Trigger 692257829 / GRB 221209243)
  66. GRB 221209A: Fermi GBM Final Real-time Localization
  67. GRB 221206B: Fermi GBM observation
  68. GRB 221206B: Swift-XRT observations
  69. GRB 221206B: Detection by GRBAlpha
  70. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  71. GRB 221206B: Swift ToO observations
  72. Swift/BAT trigger #1143281 is not a GRB
  73. GRB 221206C: Fermi GBM Final Real-time Localization
  74. GRB 221206B: Fermi GBM Final Real-time Localization
  75. GRB 221206A: Fermi GBM Final Real-time Localization
  76. GRB 221205A: Fermi GBM Final Real-time Localization
  77. Swift GRB221204.45 AKO Upper Limit
  78. GRB 221202B: Detection by VZLUSAT-2
  79. Swift GRB221204.45: Global MASTER-Net observations report
  80. GRB 221203B: Fermi GBM Final Real-time Localization
  81. GRB 221202A: Swift/UVOT Detection
  82. GRB 221202A: Swift-BAT refined analysis
  83. GRB 221202A: VLT/FORS2 Afterglow Discovery
  84. GRB 221201A: Swift-BAT refined analysis
  85. GRB 221203A: Fermi GBM Final Real-time Localization
  86. GRB 221201A: Fermi GBM observation
  87. GRB 221202A: Swift-XRT refined Analysis
  88. GRB 221202A: LCOGT Optical Upper Limits
  89. GRB 221202A: Enhanced Swift-XRT position
  90. GRB 221202A: MeerLICHT upper limits
  91. GRB 221202B: Fermi GBM Final Real-time Localization
  92. GRB 221202A: Swift detection of a burst
  93. Swift GRB221202.84: Global MASTER-Net observations report
  94. GCN: GRB 221201A: Swift/UVOT Upper Limits
  95. GRB 221201A: Swift-XRT refined Analysis
  96. GRB 221201A: Enhanced Swift-XRT position
  97. Swift GRB 221201A: Global MASTER-Net observations report
  98. Konus-Wind detection of GRB 221124A
  99. GRB 221201A: Swift detection of a burst
  100. GRB 221201A: Fermi GBM Final Real-time Localization

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