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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').
  1. GRB 230116D: SAO RAS redshift
  2. Fermi trigger No 695569700: Global MASTER-Net observations report
  3. GRB 230116D: Swift-XRT refined Analysis
  4. Fermi GRB 230117A: Global MASTER-Net observations report
  5. GRB 230117A: Fermi GBM Final Real-time Localization
  6. GRB 230116D: GIT optical follow-up
  7. GRB 230116D: GIT optical follow-up
  8. GRB 230116D: Enhanced Swift-XRT position
  9. GRB 230116D: SAO RAS observations of OT brightening
  10. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  11. GRB 230116D: Nanshan/NEXT optical afterglow detection
  12. GRB 230116D: Swift detection of a burst
  13. Swift GRB230116.88: Global MASTER-Net observations report
  14. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  15. GRB 230116C: Swift detection of a burst
  16. GRB 230116B: Fermi GBM Final Real-time Localization
  17. GRB 230116A: Fermi GBM Final Real-time Localization
  18. GRB 230114A: Detection by VZLUSAT-2
  19. Fermi-LAT gamma-ray observations of IceCube-230112A
  20. GRB 230114A: Fermi GBM Final Real-time Localization
  21. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  22. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  23. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  25. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  26. GRB 230111A: Fermi GBM Observation
  27. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  28. Fermi GRB 230112A: Global MASTER-Net observations report
  29. IceCube Alert 230112.28: Global MASTER-Net observations report
  30. GRB 230112A: Fermi GBM Final Real-time Localization
  31. GRB 230111A: MAXI/GSC detection
  32. GRB 230111A: Fermi GBM Final Real-time Localization
  33. GRB 230106: AstroSat LAXPC detection
  34. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  35. Fermi trigger No 695057654: Global MASTER-Net observations report
  36. IceCube-221223A: JCMT/SCUBA2 observations
  37. GRB 230102A: Fermi GBM Observation
  38. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  39. GRB 221231A: 3.6m DOT optical upper limit
  40. GRB 230104A: AGILE/MCAL detection of a burst
  41. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  42. GRB 221231A: Fermi GBM Observation
  43. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  44. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  45. GRB 230102A: Detection by GRBAlpha
  46. Fermi Gamma-ray Burst Monitor trigger 694302022/230101903 is not a GRB
  47. GRB 230101A: AstroSat CZTI detection
  48. Fermi trigger No 694259491: Global MASTER-Net observations report
  49. GRB 221231A: Swift-XRT afterglow detection
  50. GRB 230102A: AGILE/MCAL detection
  51. GRB 230102A: Fermi GBM Final Real-time Localization
  52. GRB 221231A: AKO Upper Limit
  53. GRB 221231A: Swift-XRT observations
  54. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  55. GRB 221231A: Swift ToO observations
  56. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  57. Fermi trigger No 694232203: Global MASTER-Net observations report
  58. GRB 230101A: Fermi GBM Final Real-time Localization
  59. GRB 221231A: Fermi GBM Final Real-time Localization
  60. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  61. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  62. Fermi-LAT gamma-ray observations of IceCube-221229A
  63. GRB 221226A: Fermi GBM detection
  64. IceCube-221229A: BOOTES-2/TELMA Optical Upper Limit
  65. IPN triangulation of GRB 221226A
  66. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  68. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  69. GRB 221226B: LCOGT Optical Upper Limits
  70. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  71. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 221228A: Fermi GBM Final Real-time Localization
  73. GRB 221226B Swift-BAT refined analysis
  74. GRB 221226B: Swift-UVOT Detection
  75. GRB 221226A: AGILE detection
  76. GRB 221226B: Fermi GBM Observation
  77. GRB 221226B: Swift-XRT refined Analysis
  78. GRB 221226B: VLT/X-shooter redshift and host galaxy
  79. GRB 221226B: Enhanced Swift-XRT position
  80. GRB 221226B: Swift detection of a burst
  81. GRB 221226B: Fermi GBM Final Real-time Localization
  82. Swift GRB221226.95: Global MASTER-Net observations report
  83. Fermi GRB 221226A: Global MASTER-Net observations report
  84. GRB 221226A: Fermi GBM Final Real-time Localization
  85. Fermi-LAT gamma-ray observations of IceCube-221224A
  86. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  87. IceCube-221223A: BOOTES-4/MET Optical Observations
  88. Fermi-LAT gamma-ray observations of IceCube-221223A
  89. Fermi GRB 221223A: Global MASTER-Net observations report
  90. IceCube Alert 221224.04: Global MASTER-Net observations report
  91. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  92. GRB 221223A: Fermi GBM Final Real-time Localization
  93. IceCube Alert 221223.32: Global MASTER-Net observations report
  94. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  95. GRB 221221A: AGILE detection
  96. Fermi GRB 221221A: Global MASTER-Net observations report
  97. GRB 221221A: Fermi GBM Final Real-time Localization
  98. GRB 221218A: 3.6m DOT optical upper limit
  99. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  100. GRB 221216A: Detection by VZLUSAT-2

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