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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 221221A: AGILE detection
  2. Fermi GRB 221221A: Global MASTER-Net observations report
  3. GRB 221221A: Fermi GBM Final Real-time Localization
  4. GRB 221218A: 3.6m DOT optical upper limit
  5. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  6. GRB 221216A: Detection by VZLUSAT-2
  7. GRB 221218A: MITSuME Akeno optical upper limits
  8. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  9. GRB 221218A: KAIT Optical Upper Limit
  10. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  11. GRB 221215A: Fermi GBM Detection
  12. GRB 221218A: a long GRB detected by INTEGRAL
  13. Integral GRB221218.34: Global MASTER-Net observations report
  14. Fermi-LAT gamma-ray observations of IceCube-221216A
  15. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 221216A: Swift/UVOT Upper Limits
  17. GRB 221216A: Fermi GBM observation
  18. GRB 221216A: Swift-XRT refined Analysis
  19. Fermi-LAT gamma-ray observations of IceCube-221210A
  20. IceCube Alert 221216.25: Global MASTER-Net observations report
  21. GRB 221216A: AKO Upper Limit
  22. GRB 221215A: Swift-XRT observations
  23. GRB 221216A: Enhanced Swift-XRT position
  24. Swift GRB 221216A: Global MASTER-Net observations report
  25. GRB 221216A: Zadko observatory - Gingin optical observations
  26. GRB 221216A: Nanshan/NEXT optical upper limits
  27. GRB 221216A: Swift detection of a burst
  28. GRB 221216A: Fermi GBM Final Real-time Localization
  29. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  30. Fermi trigger No 692760884: Global MASTER-Net observations report
  31. GRB 221215A: Swift ToO observations
  32. GRB 221215A: Swift/BAT-GUANO arcminute localization
  33. Konus-Wind detection of GRB 221209A
  34. Fermi GRB 221215B: Global MASTER-Net observations report
  35. IPN triangulation of GRB 221209A (long)
  36. GRB 221215B: Fermi GBM Final Real-time Localization
  37. Fermi Gamma-ray Burst Monitor trigger 692760884/221215066 is not a GRB
  38. Swift GRB221215.15: Global MASTER-Net observations report
  39. Fermi trigger No 692713692: Global MASTER-Net observations report
  40. GRB 221215A: Fermi GBM Final Real-time Localization
  41. Swift Trigger 1144538 is not a GRB
  42. Fermi Gamma-ray Burst Monitor triggers 692721536/221214610 and 692713692/221214520 are not GRBs
  43. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13
  44. Fermi trigger No 692607435: Global MASTER-Net observations report
  45. GRB 221209A: CALET Gamma-Ray Burst Monitor detection
  46. IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 221212A: Fermi GBM Final Real-time Localization
  48. Fermi GRB 221211A: Global MASTER-Net observations report
  49. GRB 221208A: AstroSat CZTI detection
  50. GRB 221211A: Fermi GBM Final Real-time Localization
  51. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  52. IceCube Alert 221210.36: Global MASTER-Net observations report
  53. GRB 221009A: MuSCAT3 observations
  54. GRB 221209A: AstroSat CZTI detection
  55. GRB 221210A: Fermi GBM Final Real-time Localization
  56. GRB 221209B: Fermi GBM Final Real-time Localization
  57. GRB 221209A: Fermi GBM observation
  58. GRB 221203C: AstroSat CZTI detection
  59. GRB 221209A: BALROG localization (Fermi Trigger 692257829 / GRB 221209243)
  60. GRB 221209A: Fermi GBM Final Real-time Localization
  61. GRB 221206B: Fermi GBM observation
  62. GRB 221206B: Swift-XRT observations
  63. GRB 221206B: Detection by GRBAlpha
  64. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  65. GRB 221206B: Swift ToO observations
  66. Swift/BAT trigger #1143281 is not a GRB
  67. GRB 221206C: Fermi GBM Final Real-time Localization
  68. GRB 221206B: Fermi GBM Final Real-time Localization
  69. GRB 221206A: Fermi GBM Final Real-time Localization
  70. GRB 221205A: Fermi GBM Final Real-time Localization
  71. Swift GRB221204.45 AKO Upper Limit
  72. GRB 221202B: Detection by VZLUSAT-2
  73. Swift GRB221204.45: Global MASTER-Net observations report
  74. GRB 221203B: Fermi GBM Final Real-time Localization
  75. GRB 221202A: Swift/UVOT Detection
  76. GRB 221202A: Swift-BAT refined analysis
  77. GRB 221202A: VLT/FORS2 Afterglow Discovery
  78. GRB 221201A: Swift-BAT refined analysis
  79. GRB 221203A: Fermi GBM Final Real-time Localization
  80. GRB 221201A: Fermi GBM observation
  81. GRB 221202A: Swift-XRT refined Analysis
  82. GRB 221202A: LCOGT Optical Upper Limits
  83. GRB 221202A: Enhanced Swift-XRT position
  84. GRB 221202A: MeerLICHT upper limits
  85. GRB 221202B: Fermi GBM Final Real-time Localization
  86. GRB 221202A: Swift detection of a burst
  87. Swift GRB221202.84: Global MASTER-Net observations report
  88. GCN: GRB 221201A: Swift/UVOT Upper Limits
  89. GRB 221201A: Swift-XRT refined Analysis
  90. GRB 221201A: Enhanced Swift-XRT position
  91. Swift GRB 221201A: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 221124A
  93. GRB 221201A: Swift detection of a burst
  94. GRB 221201A: Fermi GBM Final Real-time Localization
  95. Fermi Gamma-ray Burst Monitor trigger 691534074/221130867 is not a GRB
  96. Optical polarization observation of GRB 221009A
  97. GRB 221126A: Fermi GBM observation
  98. IceCube-221124A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 221126A: AGILE detection
  100. GRB 221127A: Detection by GRBAlpha

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