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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 211025A: Optical Afterglow Detection
  2. GRB211023A: optical afterglow detection from Konkoly Observatory
  3. GRB 211024A: Swift ToO observations
  4. GRB 211024A: Swift/BAT-GUANO detection and candidate arcminute localization of a short burst
  5. GRB 211024B: Swift/UVOT detection
  6. GRB 211023A: Mondy optical observations
  7. GRB 211023B: Mondy optical afterglow confirmation
  8. GRB 211023B: Gemini-North Optical Observations
  9. Swift GRB 211025A: Global MASTER-Net observations report
  10. GRB 211023B: LDT Optical Afterglow Detection
  11. IceCube-211023A: Upper limits from a search for additional neutrino events in IceCube
  12. Correction to GCN 30965: GRB 211023A: Fermi GBM detection
  13. GRB 211025A: Swift-BAT refined analysis
  14. GRB 211025A: Swift-XRT refined Analysis
  15. GRB 211024B: CAHA 2.2m Detection; ultra-long GRB?
  16. GRB 211024B: Swift-XRT refined Analysis
  17. IPN Triangulation of GRB 211019A
  18. Possible Short GRB 211023B: CAHA 2.2m Detection
  19. GRB 211025A: Swift/UVOT Detection
  20. GRB 211023A: 1.5m OSN optical observation
  21. GRB 211024B: Swift-BAT refined analysis
  22. GRB 210610B: Sintesz-Newton/CrAO optical observations
  23. GRB 211025A: Enhanced Swift-XRT position
  24. GRB 211025A: Swift detection of a burst
  25. GECAM detection of a short burst probably from SGR J1555.2-5402
  26. GRB 211024B: Nanshan/NEXT optical afterglow detection
  27. GRB 210919A: FORS2/VLT observations
  28. GRB 211023A: OAJ Bright Afterglow Confirmation
  29. Swift GRB 211024B: Global MASTER-Net observations report
  30. GRB 211024B: Swift detection of a burst
  31. GRB 211023B: Swift-BAT refined analysis
  32. Fermi-LAT Gamma-ray Observations of IceCube-211023A
  33. GRB 211023A: MASTER OT J045237.07+851925.2 - optical counterpart discovery
  34. GRB 211023B: BOOTES-4/MET and 1.5m OSN optical upper limit
  35. GRB 211023B: Swift/UVOT Detection
  36. GRB 211024A: GECAM detection
  37. GRB 211023B: RATIR Optical and NIR Upper Limits
  38. GRB 211023B: TSHAO optical observation
  39. IceCube-211023A: No neutrino counterpart detected with ANTARES
  40. Fermi GRB 211023A: Global MASTER-Net observations report
  41. GRB 211023A: AGILE detection
  42. GRB 211022A: AstroSat CZTI detection
  43. GRB 211023B: Swift-XRT refined Analysis
  44. GRB 211023B: Enhanced Swift-XRT position
  45. GRB 211023A: Fermi GBM detection
  46. Swift GRB 211023B: Global MASTER-Net observations report
  47. Fermi GRB 211024A: Global MASTER-Net observations report
  48. GRB 211024A: Fermi GBM Final Real-time Localization
  49. GRB 211023A: Fermi-LAT detection
  50. GRB 211023B: Swift detection of a possibly short burst with an optical counterpart
  51. IceCube Alert 211023.36: Global MASTER-Net observations report
  52. GRB 211023A: Fermi GBM Final Real-time Localization
  53. IceCube-211023A - IceCube observation of a high-energy neutrino candidate track-like event
  54. IPN Triangulation of GRB 210927B
  55. GRB 211022A: GECAM detection
  56. AMON IC_HAWC NuEm-211020A: No neutrino counterpart detected with ANTARES
  57. GRB 211018A: Swift ToO observations
  58. GRB 211021A: BALROG localization (Fermi Trigger 656506979 / GRB 211021460)
  59. Fermi trigger No 656506979: Global MASTER-Net observations report
  60. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211020A
  61. BepiColombo MGNS joins the IPN
  62. Fermi trigger No 656268212: Global MASTER-Net observations report
  63. GRB 211018A: Fermi GBM observation
  64. GRB 211019A: Detection by GRBAlpha
  65. GRB 211018A: Detection by GRBAlpha
  66. Fermi GRB 211019A: Global MASTER-Net observations report
  67. GRB 211018A: Fermi-LAT detection
  68. GRB 211019A: BALROG localization (Fermi Trigger 656315976 / GRB 211019250)
  69. GRB 211019A: Fermi GBM Final Real-time Localization
  70. Fermi trigger No 656288898: Global MASTER-Net observations report
  71. Swift GRB211017.99: Global MASTER-Net observations report
  72. Integral GRB211016.42: Global MASTER-Net observations report
  73. IceCube-210922A: Hard X-ray flux limit for JCMT/SCUBA2 source from NuSTAR observations
  74. Swift trigger 1078701: MITSuME Akeno optical upper limits
  75. Fermi trigger No 655673024: Global MASTER-Net observations report
  76. GRB 210919A: LDT optical observations and candidate host galaxies
  77. IceCube-20210922A: No optical counterparts found by MITSuME observations
  78. Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
  79. Fermi trigger No 655646385: Global MASTER-Net observations report
  80. Swift GRB211010.45: Global MASTER-Net observations report
  81. Swift Trigger 1078701 is probably not a GRB
  82. Fermi Gamma-ray Burst Monitor trigger 211008665/655401471 is not a GRB
  83. IceCube-20210922A: DESNU Optical counterpart candidate from 5 nights of DECam observations
  84. GRB 211008A: BALROG localization (Fermi Trigger 655401471 / GRB 211008665)
  85. Fermi trigger No 655401471: Global MASTER-Net observations report
  86. GRB 210928A: MeerKAT detection
  87. IceCube-210922A: DESI Observations
  88. GECAM observation of a burst from SGR J1555.2-5402
  89. Konus-Wind detection of GRB 210928A
  90. Fermi trigger No 654854799: Global MASTER-Net observations report
  91. Correction to GCN 30915: GRB 210928A: Swift-XRT analysis
  92. GRB 210928A: Kinder SLT-40cm optical limits
  93. GRB 210930A: Swift-BAT refined analysis
  94. SGR 1935+2154: Swift/BAT-GUANO detection and arcminute localization
  95. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  96. GRB 210928A: Swift-XRT refined Analysis
  97. GRB 210928A: Fermi GBM observation
  98. GRB 210928A: Fermi-LAT detection
  99. Swift GRB211001.03 / trigger 1076121 : MASTER OT retraction
  100. GRB 210927B: GECAM detection

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