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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 230118A: Fermi GBM Final Real-time Localization
  2. GRB 230116D: Swift-BAT refined analysis
  3. GRB 230116C: Swift-BAT refined analysis
  4. GRB 230116D: SAO RAS further observations
  5. GRB 230116D: SAO RAS photometry
  6. GRB 230116D: KGO RC-25 optical observations
  7. GRB 230116D: Sintez-Newton/CrAO optical observations
  8. GRB 230116D: LCOGT Optical Upper Limit
  9. GRB 230116D: SAO RAS redshift
  10. Fermi trigger No 695569700: Global MASTER-Net observations report
  11. GRB 230116D: Swift-XRT refined Analysis
  12. Fermi GRB 230117A: Global MASTER-Net observations report
  13. GRB 230117A: Fermi GBM Final Real-time Localization
  14. GRB 230116D: GIT optical follow-up
  15. GRB 230116D: GIT optical follow-up
  16. GRB 230116D: Enhanced Swift-XRT position
  17. GRB 230116D: SAO RAS observations of OT brightening
  18. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  19. GRB 230116D: Nanshan/NEXT optical afterglow detection
  20. GRB 230116D: Swift detection of a burst
  21. Swift GRB230116.88: Global MASTER-Net observations report
  22. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  23. GRB 230116C: Swift detection of a burst
  24. GRB 230116B: Fermi GBM Final Real-time Localization
  25. GRB 230116A: Fermi GBM Final Real-time Localization
  26. GRB 230114A: Detection by VZLUSAT-2
  27. Fermi-LAT gamma-ray observations of IceCube-230112A
  28. GRB 230114A: Fermi GBM Final Real-time Localization
  29. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  30. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  31. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  32. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  33. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  34. GRB 230111A: Fermi GBM Observation
  35. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  36. Fermi GRB 230112A: Global MASTER-Net observations report
  37. IceCube Alert 230112.28: Global MASTER-Net observations report
  38. GRB 230112A: Fermi GBM Final Real-time Localization
  39. GRB 230111A: MAXI/GSC detection
  40. GRB 230111A: Fermi GBM Final Real-time Localization
  41. GRB 230106: AstroSat LAXPC detection
  42. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  43. Fermi trigger No 695057654: Global MASTER-Net observations report
  44. IceCube-221223A: JCMT/SCUBA2 observations
  45. GRB 230102A: Fermi GBM Observation
  46. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  47. GRB 221231A: 3.6m DOT optical upper limit
  48. GRB 230104A: AGILE/MCAL detection of a burst
  49. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  50. GRB 221231A: Fermi GBM Observation
  51. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  52. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  53. GRB 230102A: Detection by GRBAlpha
  54. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  55. GRB 230101A: AstroSat CZTI detection
  56. Fermi trigger No 694259491: Global MASTER-Net observations report
  57. GRB 221231A: Swift-XRT afterglow detection
  58. GRB 230102A: AGILE/MCAL detection
  59. GRB 230102A: Fermi GBM Final Real-time Localization
  60. GRB 221231A: AKO Upper Limit
  61. GRB 221231A: Swift-XRT observations
  62. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  63. GRB 221231A: Swift ToO observations
  64. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  65. Fermi trigger No 694232203: Global MASTER-Net observations report
  66. GRB 230101A: Fermi GBM Final Real-time Localization
  67. GRB 221231A: Fermi GBM Final Real-time Localization
  68. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  69. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  70. Fermi-LAT gamma-ray observations of IceCube-221229A
  71. GRB 221226A: Fermi GBM detection
  72. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  73. IPN triangulation of GRB 221226A
  74. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  76. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  77. GRB 221226B: LCOGT Optical Upper Limits
  78. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  79. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  80. GRB 221228A: Fermi GBM Final Real-time Localization
  81. GRB 221226B Swift-BAT refined analysis
  82. GRB 221226B: Swift-UVOT Detection
  83. GRB 221226A: AGILE detection
  84. GRB 221226B: Fermi GBM Observation
  85. GRB 221226B: Swift-XRT refined Analysis
  86. GRB 221226B: VLT/X-shooter redshift and host galaxy
  87. GRB 221226B: Enhanced Swift-XRT position
  88. GRB 221226B: Swift detection of a burst
  89. GRB 221226B: Fermi GBM Final Real-time Localization
  90. Swift GRB221226.95: Global MASTER-Net observations report
  91. Fermi GRB 221226A: Global MASTER-Net observations report
  92. GRB 221226A: Fermi GBM Final Real-time Localization
  93. Fermi-LAT gamma-ray observations of IceCube-221224A
  94. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  95. IceCube-221223A: BOOTES-4/MET Optical Observations
  96. Fermi-LAT gamma-ray observations of IceCube-221223A
  97. Fermi GRB 221223A: Global MASTER-Net observations report
  98. IceCube Alert 221224.04: Global MASTER-Net observations report
  99. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  100. GRB 221223A: Fermi GBM Final Real-time Localization

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