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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 230119A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 230116D: 3.6m DOT optical upper limit
  3. GRB 230119A: Fermi GBM Final Real-time Localization
  4. Fermi GRB 230118A: Global MASTER-Net observations report
  5. GRB 230118A: Fermi GBM Final Real-time Localization
  6. GRB 230116D: Swift-BAT refined analysis
  7. GRB 230116C: Swift-BAT refined analysis
  8. GRB 230116D: SAO RAS further observations
  9. GRB 230116D: SAO RAS photometry
  10. GRB 230116D: KGO RC-25 optical observations
  11. GRB 230116D: Sintez-Newton/CrAO optical observations
  12. GRB 230116D: LCOGT Optical Upper Limit
  13. GRB 230116D: SAO RAS redshift
  14. Fermi trigger No 695569700: Global MASTER-Net observations report
  15. GRB 230116D: Swift-XRT refined Analysis
  16. Fermi GRB 230117A: Global MASTER-Net observations report
  17. GRB 230117A: Fermi GBM Final Real-time Localization
  18. GRB 230116D: GIT optical follow-up
  19. GRB 230116D: GIT optical follow-up
  20. GRB 230116D: Enhanced Swift-XRT position
  21. GRB 230116D: SAO RAS observations of OT brightening
  22. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  23. GRB 230116D: Nanshan/NEXT optical afterglow detection
  24. GRB 230116D: Swift detection of a burst
  25. Swift GRB230116.88: Global MASTER-Net observations report
  26. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  27. GRB 230116C: Swift detection of a burst
  28. GRB 230116B: Fermi GBM Final Real-time Localization
  29. GRB 230116A: Fermi GBM Final Real-time Localization
  30. GRB 230114A: Detection by VZLUSAT-2
  31. Fermi-LAT gamma-ray observations of IceCube-230112A
  32. GRB 230114A: Fermi GBM Final Real-time Localization
  33. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  34. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  35. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  36. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  37. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  38. GRB 230111A: Fermi GBM Observation
  39. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  40. Fermi GRB 230112A: Global MASTER-Net observations report
  41. IceCube Alert 230112.28: Global MASTER-Net observations report
  42. GRB 230112A: Fermi GBM Final Real-time Localization
  43. GRB 230111A: MAXI/GSC detection
  44. GRB 230111A: Fermi GBM Final Real-time Localization
  45. GRB 230106: AstroSat LAXPC detection
  46. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  47. Fermi trigger No 695057654: Global MASTER-Net observations report
  48. IceCube-221223A: JCMT/SCUBA2 observations
  49. GRB 230102A: Fermi GBM Observation
  50. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  51. GRB 221231A: 3.6m DOT optical upper limit
  52. GRB 230104A: AGILE/MCAL detection of a burst
  53. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  54. GRB 221231A: Fermi GBM Observation
  55. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  56. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  57. GRB 230102A: Detection by GRBAlpha
  58. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  59. GRB 230101A: AstroSat CZTI detection
  60. Fermi trigger No 694259491: Global MASTER-Net observations report
  61. GRB 221231A: Swift-XRT afterglow detection
  62. GRB 230102A: AGILE/MCAL detection
  63. GRB 230102A: Fermi GBM Final Real-time Localization
  64. GRB 221231A: AKO Upper Limit
  65. GRB 221231A: Swift-XRT observations
  66. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  67. GRB 221231A: Swift ToO observations
  68. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  69. Fermi trigger No 694232203: Global MASTER-Net observations report
  70. GRB 230101A: Fermi GBM Final Real-time Localization
  71. GRB 221231A: Fermi GBM Final Real-time Localization
  72. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  73. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  74. Fermi-LAT gamma-ray observations of IceCube-221229A
  75. GRB 221226A: Fermi GBM detection
  76. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  77. IPN triangulation of GRB 221226A
  78. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  80. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  81. GRB 221226B: LCOGT Optical Upper Limits
  82. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  83. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 221228A: Fermi GBM Final Real-time Localization
  85. GRB 221226B Swift-BAT refined analysis
  86. GRB 221226B: Swift-UVOT Detection
  87. GRB 221226A: AGILE detection
  88. GRB 221226B: Fermi GBM Observation
  89. GRB 221226B: Swift-XRT refined Analysis
  90. GRB 221226B: VLT/X-shooter redshift and host galaxy
  91. GRB 221226B: Enhanced Swift-XRT position
  92. GRB 221226B: Swift detection of a burst
  93. GRB 221226B: Fermi GBM Final Real-time Localization
  94. Swift GRB221226.95: Global MASTER-Net observations report
  95. Fermi GRB 221226A: Global MASTER-Net observations report
  96. GRB 221226A: Fermi GBM Final Real-time Localization
  97. Fermi-LAT gamma-ray observations of IceCube-221224A
  98. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  99. IceCube-221223A: BOOTES-4/MET Optical Observations
  100. Fermi-LAT gamma-ray observations of IceCube-221223A

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