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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 230116D: Swift-BAT refined analysis
  2. GRB 230116C: Swift-BAT refined analysis
  3. GRB 230116D: SAO RAS further observations
  4. GRB 230116D: SAO RAS photometry
  5. GRB 230116D: KGO RC-25 optical observations
  6. GRB 230116D: Sintez-Newton/CrAO optical observations
  7. GRB 230116D: LCOGT Optical Upper Limit
  8. GRB 230116D: SAO RAS redshift
  9. Fermi trigger No 695569700: Global MASTER-Net observations report
  10. GRB 230116D: Swift-XRT refined Analysis
  11. Fermi GRB 230117A: Global MASTER-Net observations report
  12. GRB 230117A: Fermi GBM Final Real-time Localization
  13. GRB 230116D: GIT optical follow-up
  14. GRB 230116D: GIT optical follow-up
  15. GRB 230116D: Enhanced Swift-XRT position
  16. GRB 230116D: SAO RAS observations of OT brightening
  17. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  18. GRB 230116D: Nanshan/NEXT optical afterglow detection
  19. GRB 230116D: Swift detection of a burst
  20. Swift GRB230116.88: Global MASTER-Net observations report
  21. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  22. GRB 230116C: Swift detection of a burst
  23. GRB 230116B: Fermi GBM Final Real-time Localization
  24. GRB 230116A: Fermi GBM Final Real-time Localization
  25. GRB 230114A: Detection by VZLUSAT-2
  26. Fermi-LAT gamma-ray observations of IceCube-230112A
  27. GRB 230114A: Fermi GBM Final Real-time Localization
  28. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  29. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  30. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  31. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  32. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  33. GRB 230111A: Fermi GBM Observation
  34. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  35. Fermi GRB 230112A: Global MASTER-Net observations report
  36. IceCube Alert 230112.28: Global MASTER-Net observations report
  37. GRB 230112A: Fermi GBM Final Real-time Localization
  38. GRB 230111A: MAXI/GSC detection
  39. GRB 230111A: Fermi GBM Final Real-time Localization
  40. GRB 230106: AstroSat LAXPC detection
  41. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  42. Fermi trigger No 695057654: Global MASTER-Net observations report
  43. IceCube-221223A: JCMT/SCUBA2 observations
  44. GRB 230102A: Fermi GBM Observation
  45. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  46. GRB 221231A: 3.6m DOT optical upper limit
  47. GRB 230104A: AGILE/MCAL detection of a burst
  48. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  49. GRB 221231A: Fermi GBM Observation
  50. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  51. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  52. GRB 230102A: Detection by GRBAlpha
  53. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  54. GRB 230101A: AstroSat CZTI detection
  55. Fermi trigger No 694259491: Global MASTER-Net observations report
  56. GRB 221231A: Swift-XRT afterglow detection
  57. GRB 230102A: AGILE/MCAL detection
  58. GRB 230102A: Fermi GBM Final Real-time Localization
  59. GRB 221231A: AKO Upper Limit
  60. GRB 221231A: Swift-XRT observations
  61. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  62. GRB 221231A: Swift ToO observations
  63. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  64. Fermi trigger No 694232203: Global MASTER-Net observations report
  65. GRB 230101A: Fermi GBM Final Real-time Localization
  66. GRB 221231A: Fermi GBM Final Real-time Localization
  67. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  68. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  69. Fermi-LAT gamma-ray observations of IceCube-221229A
  70. GRB 221226A: Fermi GBM detection
  71. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  72. IPN triangulation of GRB 221226A
  73. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  75. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  76. GRB 221226B: LCOGT Optical Upper Limits
  77. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  78. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 221228A: Fermi GBM Final Real-time Localization
  80. GRB 221226B Swift-BAT refined analysis
  81. GRB 221226B: Swift-UVOT Detection
  82. GRB 221226A: AGILE detection
  83. GRB 221226B: Fermi GBM Observation
  84. GRB 221226B: Swift-XRT refined Analysis
  85. GRB 221226B: VLT/X-shooter redshift and host galaxy
  86. GRB 221226B: Enhanced Swift-XRT position
  87. GRB 221226B: Swift detection of a burst
  88. GRB 221226B: Fermi GBM Final Real-time Localization
  89. Swift GRB221226.95: Global MASTER-Net observations report
  90. Fermi GRB 221226A: Global MASTER-Net observations report
  91. GRB 221226A: Fermi GBM Final Real-time Localization
  92. Fermi-LAT gamma-ray observations of IceCube-221224A
  93. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  94. IceCube-221223A: BOOTES-4/MET Optical Observations
  95. Fermi-LAT gamma-ray observations of IceCube-221223A
  96. Fermi GRB 221223A: Global MASTER-Net observations report
  97. IceCube Alert 221224.04: Global MASTER-Net observations report
  98. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 221223A: Fermi GBM Final Real-time Localization
  100. IceCube Alert 221223.32: Global MASTER-Net observations report

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