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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 211023A: AGILE detection
  2. GRB 211022A: AstroSat CZTI detection
  3. GRB 211023B: Swift-XRT refined Analysis
  4. GRB 211023B: Enhanced Swift-XRT position
  5. GRB 211023A: Fermi GBM detection
  6. Swift GRB 211023B: Global MASTER-Net observations report
  7. Fermi GRB 211024A: Global MASTER-Net observations report
  8. GRB 211024A: Fermi GBM Final Real-time Localization
  9. GRB 211023A: Fermi-LAT detection
  10. GRB 211023B: Swift detection of a possibly short burst with an optical counterpart
  11. IceCube Alert 211023.36: Global MASTER-Net observations report
  12. GRB 211023A: Fermi GBM Final Real-time Localization
  13. IceCube-211023A - IceCube observation of a high-energy neutrino candidate track-like event
  14. IPN Triangulation of GRB 210927B
  15. GRB 211022A: GECAM detection
  16. AMON IC_HAWC NuEm-211020A: No neutrino counterpart detected with ANTARES
  17. GRB 211018A: Swift ToO observations
  18. GRB 211021A: BALROG localization (Fermi Trigger 656506979 / GRB 211021460)
  19. Fermi trigger No 656506979: Global MASTER-Net observations report
  20. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211020A
  21. BepiColombo MGNS joins the IPN
  22. Fermi trigger No 656268212: Global MASTER-Net observations report
  23. GRB 211018A: Fermi GBM observation
  24. GRB 211019A: Detection by GRBAlpha
  25. GRB 211018A: Detection by GRBAlpha
  26. Fermi GRB 211019A: Global MASTER-Net observations report
  27. GRB 211018A: Fermi-LAT detection
  28. GRB 211019A: BALROG localization (Fermi Trigger 656315976 / GRB 211019250)
  29. GRB 211019A: Fermi GBM Final Real-time Localization
  30. Fermi trigger No 656288898: Global MASTER-Net observations report
  31. Swift GRB211017.99: Global MASTER-Net observations report
  32. Integral GRB211016.42: Global MASTER-Net observations report
  33. IceCube-210922A: Hard X-ray flux limit for JCMT/SCUBA2 source from NuSTAR observations
  34. Swift trigger 1078701: MITSuME Akeno optical upper limits
  35. Fermi trigger No 655673024: Global MASTER-Net observations report
  36. GRB 210919A: LDT optical observations and candidate host galaxies
  37. IceCube-20210922A: No optical counterparts found by MITSuME observations
  38. Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
  39. Fermi trigger No 655646385: Global MASTER-Net observations report
  40. Swift GRB211010.45: Global MASTER-Net observations report
  41. Swift Trigger 1078701 is probably not a GRB
  42. Fermi Gamma-ray Burst Monitor trigger 211008665/655401471 is not a GRB
  43. IceCube-20210922A: DESNU Optical counterpart candidate from 5 nights of DECam observations
  44. GRB 211008A: BALROG localization (Fermi Trigger 655401471 / GRB 211008665)
  45. Fermi trigger No 655401471: Global MASTER-Net observations report
  46. GRB 210928A: MeerKAT detection
  47. IceCube-210922A: DESI Observations
  48. GECAM observation of a burst from SGR J1555.2-5402
  49. Konus-Wind detection of GRB 210928A
  50. Fermi trigger No 654854799: Global MASTER-Net observations report
  51. Correction to GCN 30915: GRB 210928A: Swift-XRT analysis
  52. GRB 210928A: Kinder SLT-40cm optical limits
  53. GRB 210930A: Swift-BAT refined analysis
  54. SGR 1935+2154: Swift/BAT-GUANO detection and arcminute localization
  55. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  56. GRB 210928A: Swift-XRT refined Analysis
  57. GRB 210928A: Fermi GBM observation
  58. GRB 210928A: Fermi-LAT detection
  59. Swift GRB211001.03 / trigger 1076121 : MASTER OT retraction
  60. GRB 210927B: GECAM detection
  61. GRB 210930A: CAHA 2.2m telescope optical limit
  62. GRB 210927A: GIT optical follow-up of ZTF21acdwctm.
  63. Fermi trigger No 654739449: Global MASTER-Net observations report
  64. Swift GRB211001.03: Global MASTER-Net observations report
  65. Swift Trigger 1076121 is not a GRB
  66. Swift GRB211001.03: Global MASTER-Net OT detection
  67. GRB 210930A: Swift/UVOT Upper Limits
  68. GRB 210930A: Swift-XRT refined Analysis
  69. Swift GRB 210930A: Global MASTER-Net observations report
  70. GRB 210930A: Enhanced Swift-XRT position
  71. Fermi trigger No 654658271: Global MASTER-Net observations report
  72. Fermi GRB 210929B: Global MASTER-Net observations report
  73. GRB 210930A: Swift detection of a burst
  74. GRB 210929B: Fermi GBM Final Real-time Localization
  75. Fermi-LAT Gamma-ray Observations of IceCubeCascade-210926A
  76. GRB 210929A: Fermi GBM Final Real-time Localization
  77. GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
  78. GRB 210925B: AstroSat CZTI detection
  79. IceCube-210922A: SMA observation for the JCMT candidate
  80. IPN triangulation of GRB 210925B
  81. GRB 210926A: AstroSat CZTI detection
  82. GRB 210919A: iTelescope T-11 upper limits
  83. IceCube-210926A: No neutrino counterpart candidates in ANTARES search
  84. GRB 210926A: GECAM detection
  85. GRB 210927A: Fermi GBM Final Real-time Localization
  86. GRB 210919A OSN 1.5m Source Confirmation
  87. GRB 210919A CAHA 2.2m Observations: Afterglow/Host Galaxy Candidate
  88. IceCube-210922A: JCMT/SCUBA2 observations
  89. GRB 210925A: GECAM detection
  90. GRB 210925A: Fermi GBM Final Real-time Localization
  91. GRB 210919A: Chandra rapid ToO upper limit
  92. GRB 210924A: Fermi GBM Final Real-time Localization
  93. IceCube-210922A: No Candidate Counterparts from Swift/XRT follow up observations
  94. IceCube-210922A: No significant detection in HAWC
  95. IceCube-210922A: No neutrino counterpart candidates in ANTARES search
  96. GRB 210923B: GECAM detection
  97. Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
  98. IceCube-210922A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-210922A: Upper limits from Fermi-GBM Observations
  100. IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility

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