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

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