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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-XRT refined Analysis
  2. Fermi GRB 230117A: Global MASTER-Net observations report
  3. GRB 230117A: Fermi GBM Final Real-time Localization
  4. GRB 230116D: GIT optical follow-up
  5. GRB 230116D: GIT optical follow-up
  6. GRB 230116D: Enhanced Swift-XRT position
  7. GRB 230116D: SAO RAS observations of OT brightening
  8. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  9. GRB 230116D: Nanshan/NEXT optical afterglow detection
  10. GRB 230116D: Swift detection of a burst
  11. Swift GRB230116.88: Global MASTER-Net observations report
  12. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  13. GRB 230116C: Swift detection of a burst
  14. GRB 230116B: Fermi GBM Final Real-time Localization
  15. GRB 230116A: Fermi GBM Final Real-time Localization
  16. GRB 230114A: Detection by VZLUSAT-2
  17. Fermi-LAT gamma-ray observations of IceCube-230112A
  18. GRB 230114A: Fermi GBM Final Real-time Localization
  19. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  20. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  21. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  22. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  23. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  24. GRB 230111A: Fermi GBM Observation
  25. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  26. Fermi GRB 230112A: Global MASTER-Net observations report
  27. IceCube Alert 230112.28: Global MASTER-Net observations report
  28. GRB 230112A: Fermi GBM Final Real-time Localization
  29. GRB 230111A: MAXI/GSC detection
  30. GRB 230111A: Fermi GBM Final Real-time Localization
  31. GRB 230106: AstroSat LAXPC detection
  32. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  33. Fermi trigger No 695057654: Global MASTER-Net observations report
  34. IceCube-221223A: JCMT/SCUBA2 observations
  35. GRB 230102A: Fermi GBM Observation
  36. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  37. GRB 221231A: 3.6m DOT optical upper limit
  38. GRB 230104A: AGILE/MCAL detection of a burst
  39. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  40. GRB 221231A: Fermi GBM Observation
  41. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  42. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  43. GRB 230102A: Detection by GRBAlpha
  44. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  45. GRB 230101A: AstroSat CZTI detection
  46. Fermi trigger No 694259491: Global MASTER-Net observations report
  47. GRB 221231A: Swift-XRT afterglow detection
  48. GRB 230102A: AGILE/MCAL detection
  49. GRB 230102A: Fermi GBM Final Real-time Localization
  50. GRB 221231A: AKO Upper Limit
  51. GRB 221231A: Swift-XRT observations
  52. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  53. GRB 221231A: Swift ToO observations
  54. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  55. Fermi trigger No 694232203: Global MASTER-Net observations report
  56. GRB 230101A: Fermi GBM Final Real-time Localization
  57. GRB 221231A: Fermi GBM Final Real-time Localization
  58. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  59. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  60. Fermi-LAT gamma-ray observations of IceCube-221229A
  61. GRB 221226A: Fermi GBM detection
  62. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  63. IPN triangulation of GRB 221226A
  64. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  65. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  66. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  67. GRB 221226B: LCOGT Optical Upper Limits
  68. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  69. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  70. GRB 221228A: Fermi GBM Final Real-time Localization
  71. GRB 221226B Swift-BAT refined analysis
  72. GRB 221226B: Swift-UVOT Detection
  73. GRB 221226A: AGILE detection
  74. GRB 221226B: Fermi GBM Observation
  75. GRB 221226B: Swift-XRT refined Analysis
  76. GRB 221226B: VLT/X-shooter redshift and host galaxy
  77. GRB 221226B: Enhanced Swift-XRT position
  78. GRB 221226B: Swift detection of a burst
  79. GRB 221226B: Fermi GBM Final Real-time Localization
  80. Swift GRB221226.95: Global MASTER-Net observations report
  81. Fermi GRB 221226A: Global MASTER-Net observations report
  82. GRB 221226A: Fermi GBM Final Real-time Localization
  83. Fermi-LAT gamma-ray observations of IceCube-221224A
  84. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  85. IceCube-221223A: BOOTES-4/MET Optical Observations
  86. Fermi-LAT gamma-ray observations of IceCube-221223A
  87. Fermi GRB 221223A: Global MASTER-Net observations report
  88. IceCube Alert 221224.04: Global MASTER-Net observations report
  89. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 221223A: Fermi GBM Final Real-time Localization
  91. IceCube Alert 221223.32: Global MASTER-Net observations report
  92. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB 221221A: AGILE detection
  94. Fermi GRB 221221A: Global MASTER-Net observations report
  95. GRB 221221A: Fermi GBM Final Real-time Localization
  96. GRB 221218A: 3.6m DOT optical upper limit
  97. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  98. GRB 221216A: Detection by VZLUSAT-2
  99. GRB 221218A: MITSuME Akeno optical upper limits
  100. GRB 221218A: BOOTES-4/MET and OSN optical upper limits

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