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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 230123A: Swift-XRT refined Analysis
  2. GRB 230123A: Enhanced Swift-XRT position
  3. GRB 230123A: Zadko observatory - Gingin optical observations
  4. GRB 230116C: Swift-XRT observations
  5. GRB 230123A: Swift detection of a burst
  6. IceCube Alert 230122.16: Global MASTER-Net observations report
  7. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB 230116B: Fermi GBM observation
  9. Trigger 1150107: Swift detection of LS V +44 17
  10. GRB 230120A: AstroSat CZTI detection
  11. IPN triangulation of GRB 230116B (short)
  12. GRB 230119A: CALET Gamma-Ray Burst Monitor detection
  13. GRB 230116D: 3.6m DOT optical upper limit
  14. GRB 230119A: Fermi GBM Final Real-time Localization
  15. Fermi GRB 230118A: Global MASTER-Net observations report
  16. GRB 230118A: Fermi GBM Final Real-time Localization
  17. GRB 230116D: Swift-BAT refined analysis
  18. GRB 230116C: Swift-BAT refined analysis
  19. GRB 230116D: SAO RAS further observations
  20. GRB 230116D: SAO RAS photometry
  21. GRB 230116D: KGO RC-25 optical observations
  22. GRB 230116D: Sintez-Newton/CrAO optical observations
  23. GRB 230116D: LCOGT Optical Upper Limit
  24. GRB 230116D: SAO RAS redshift
  25. Fermi trigger No 695569700: Global MASTER-Net observations report
  26. GRB 230116D: Swift-XRT refined Analysis
  27. Fermi GRB 230117A: Global MASTER-Net observations report
  28. GRB 230117A: Fermi GBM Final Real-time Localization
  29. GRB 230116D: GIT optical follow-up
  30. GRB 230116D: GIT optical follow-up
  31. GRB 230116D: Enhanced Swift-XRT position
  32. GRB 230116D: SAO RAS observations of OT brightening
  33. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  34. GRB 230116D: Nanshan/NEXT optical afterglow detection
  35. GRB 230116D: Swift detection of a burst
  36. Swift GRB230116.88: Global MASTER-Net observations report
  37. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  38. GRB 230116C: Swift detection of a burst
  39. GRB 230116B: Fermi GBM Final Real-time Localization
  40. GRB 230116A: Fermi GBM Final Real-time Localization
  41. GRB 230114A: Detection by VZLUSAT-2
  42. Fermi-LAT gamma-ray observations of IceCube-230112A
  43. GRB 230114A: Fermi GBM Final Real-time Localization
  44. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  45. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  46. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  47. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  48. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  49. GRB 230111A: Fermi GBM Observation
  50. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  51. Fermi GRB 230112A: Global MASTER-Net observations report
  52. IceCube Alert 230112.28: Global MASTER-Net observations report
  53. GRB 230112A: Fermi GBM Final Real-time Localization
  54. GRB 230111A: MAXI/GSC detection
  55. GRB 230111A: Fermi GBM Final Real-time Localization
  56. GRB 230106: AstroSat LAXPC detection
  57. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  58. Fermi trigger No 695057654: Global MASTER-Net observations report
  59. IceCube-221223A: JCMT/SCUBA2 observations
  60. GRB 230102A: Fermi GBM Observation
  61. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  62. GRB 221231A: 3.6m DOT optical upper limit
  63. GRB 230104A: AGILE/MCAL detection of a burst
  64. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  65. GRB 221231A: Fermi GBM Observation
  66. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  67. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  68. GRB 230102A: Detection by GRBAlpha
  69. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  70. GRB 230101A: AstroSat CZTI detection
  71. Fermi trigger No 694259491: Global MASTER-Net observations report
  72. GRB 221231A: Swift-XRT afterglow detection
  73. GRB 230102A: AGILE/MCAL detection
  74. GRB 230102A: Fermi GBM Final Real-time Localization
  75. GRB 221231A: AKO Upper Limit
  76. GRB 221231A: Swift-XRT observations
  77. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  78. GRB 221231A: Swift ToO observations
  79. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  80. Fermi trigger No 694232203: Global MASTER-Net observations report
  81. GRB 230101A: Fermi GBM Final Real-time Localization
  82. GRB 221231A: Fermi GBM Final Real-time Localization
  83. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  85. Fermi-LAT gamma-ray observations of IceCube-221229A
  86. GRB 221226A: Fermi GBM detection
  87. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  88. IPN triangulation of GRB 221226A
  89. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  91. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  92. GRB 221226B: LCOGT Optical Upper Limits
  93. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  94. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  95. GRB 221228A: Fermi GBM Final Real-time Localization
  96. GRB 221226B Swift-BAT refined analysis
  97. GRB 221226B: Swift-UVOT Detection
  98. GRB 221226A: AGILE detection
  99. GRB 221226B: Fermi GBM Observation
  100. GRB 221226B: Swift-XRT refined Analysis

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