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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. IPN triangulation of GRB 211204C
  2. GRB 211206A: Swift/BAT-GUANO detection outside the coded FOV
  3. GRB 211206A: AGILE/MCAL detection of a burst
  4. GRB 211204C: Swift/BAT-GUANO detection outside the coded FOV
  5. GRB 211204C: GECAM detection
  6. Fermi GRB 211204C: Global MASTER-Net observations report
  7. GRB 211204C: Fermi GBM Final Real-time Localization
  8. Fermi GRB 211204B: Global MASTER-Net observations report
  9. GRB 211204B: Fermi GBM Final Real-time Localization
  10. Fermi GRB 211204A: Global MASTER-Net observations report
  11. GRB 211204A: Fermi GBM Final Real-time Localization
  12. GRB 211124A: Fermi GBM Observation
  13. Swift Trigger 1086826 (possible GRB 211203A) is likely not an astrophysical event
  14. Swift GRB 211203A: Global MASTER-Net observations report
  15. Fermi GBM Upper limits for GRB 211203A
  16. Konus-Wind detection of GRB 211130A
  17. IPN triangulation of GRB 211130A
  18. GRB 211203A: Swift detection of a burst
  19. GRB 211201A: GECAM detection
  20. GRB 211201A: Swift/BAT-GUANO detection likely outside the coded FOV
  21. GRB 211106A: Second HST Observation
  22. Fermi GRB 211201A: Global MASTER-Net observations report
  23. GRB 211201A: Fermi GBM Final Real-time Localization
  24. Fermi GRB 211130A: Global MASTER-Net observations report
  25. IceCube-211125A: No significant detection in HAWC
  26. GRB 211130A: BALROG localization (Fermi Trigger 659978192 / GRB 211130636)
  27. GRB 211130A: Fermi GBM Final Real-time Localization
  28. GRB 211106A: GECAM detection
  29. GRB 211129A: Swift-BAT refined analysis
  30. GRB 211129A: Swift-XRT refined Analysis
  31. GRB 211129A: Swift/UVOT Upper Limits
  32. GRB 211106A: HST Observations
  33. GRB 211106A: Chandra Observations
  34. IceCube-Cascade 211128A: Upper limits from a search for additional neutrino events in IceCube
  35. IceCube-211125A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 211129A: Fermi GBM observation
  37. Swift GRB 211129A: Global MASTER-Net observations report
  38. GRB 211129A: Nanshan/NEXT optical upper limit
  39. GRB 211129A: Enhanced Swift-XRT position
  40. IPN triangulation of GRB 211118A
  41. GRB 211129A: MITSuME Akeno optical upper limits
  42. GRB 211129A: Swift detection of a burst
  43. IceCube-211125A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  44. GRB 211023A: Xinglong 2.16m optical observations
  45. GRB 211023A: Xinglong 2.16m optical observations
  46. Fermi-LAT Gamma-ray Observations of IceCube-211125A
  47. GRB 211120548: Fermi GBM observation
  48. Konus-Wind detection of GRB 211120A
  49. IPN triangulation of GRB 211120A
  50. IceCube-211125A: No neutrino counterpart detected with ANTARES
  51. Chandra observations of GRB 210905A
  52. IceCube-211125A: IceCube observation of a high-energy neutrino candidate track-like event
  53. GRB 211118A: Fermi GBM detection
  54. IceCube Alert 211125.27: Global MASTER-Net observations report
  55. Fermi-LAT Gamma-ray Observations of IceCube-211123A
  56. IceCube-211123A: Upper limits from a search for additional neutrino events in IceCube
  57. IceCube-211123A: INTEGRAL was inactive at the time of the event
  58. IceCube-211123A: Upper limits from Fermi-GBM Observations
  59. IceCube-211117A: not observable by Fermi-GBM
  60. IceCube-211116A: not observable by Fermi-GBM
  61. IceCube-211023A: not observable by Fermi-GBM
  62. IPN triangulation of GRB 211124A (short)
  63. HAWC-211123A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  64. HAWC-211123A: not observable by Fermi-GBM
  65. GRB 211124A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  66. IceCube Alert 211123.60: Global MASTER-Net observations report
  67. HAWC-211123A: No neutrino counterpart detected with ANTARES
  68. IceCube-211123A - IceCube observation of a high-energy neutrino candidate track-like event
  69. Fermi trigger No 659413798: Global MASTER-Net observations report
  70. Trigger_21473: Tiled Swift observations
  71. GRB 211023B: LBT likely spectroscopic redshift of the host galaxy
  72. Alert from the HAWC Burst Monitor HAWC-211123A
  73. GRB 211120A: AGILE detection
  74. GRB 211120A: AstroSat CZTI detection
  75. Fermi trigger No 659183098: Global MASTER-Net observations report
  76. Fermi trigger No 659106591: Global MASTER-Net observations report
  77. GRB 211120B: Swift/BAT-GUANO detection outside the coded FOV
  78. GRB 211120A: GECAM detection
  79. GRB 211118A: AstroSat CZTI detection
  80. GRB 211023A: optical observations and photometric evidence of supernova
  81. Fermi-LAT Gamma-ray Observations of IceCube-211117A
  82. GRB211118A: Swift/BAT-GUANO detection outside the coded FOV
  83. Fermi trigger No 658971499: Global MASTER-Net observations report
  84. Search for counterpart to IceCube-211117A with ANTARES
  85. IceCube-211117A : IceCube observation of a high-energy neutrino candidate track-like event
  86. IceCube-211116A: Upper limits from a search for additional neutrino events in IceCube
  87. Fermi-LAT Gamma-ray Observations of IceCube-211116A
  88. IceCube-211116A: No neutrino counterpart detected with ANTARES
  89. IceCube Alert 211116.44: Global MASTER-Net observations report
  90. Fermi trigger No 658755664: Global MASTER-Net observations report
  91. Fermi trigger No 658764238: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 211107B
  93. IceCube-211116A : IceCube observation of a high-energy neutrino candidate track-like event
  94. GRB 211115A: CALET Gamma-Ray Burst Monitor detection
  95. Fermi trigger No 658686687: Global MASTER-Net observations report
  96. GRB 211115A: MAXI/GSC detection
  97. GRB 211023A: classification and SPI-ACS/INTEGRAL registration
  98. Fermi GRB 211112A: Global MASTER-Net observations report
  99. GRB 211106A: Swift/UVOT upper limits
  100. IPN triangulation of GRB 211106A (short)

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