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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. IceCube-211123A - IceCube observation of a high-energy neutrino candidate track-like event
  2. Fermi trigger No 659413798: Global MASTER-Net observations report
  3. Trigger_21473: Tiled Swift observations
  4. GRB 211023B: LBT likely spectroscopic redshift of the host galaxy
  5. Alert from the HAWC Burst Monitor HAWC-211123A
  6. GRB 211120A: AGILE detection
  7. GRB 211120A: AstroSat CZTI detection
  8. Fermi trigger No 659183098: Global MASTER-Net observations report
  9. Fermi trigger No 659106591: Global MASTER-Net observations report
  10. GRB 211120B: Swift/BAT-GUANO detection outside the coded FOV
  11. GRB 211120A: GECAM detection
  12. GRB 211118A: AstroSat CZTI detection
  13. GRB 211023A: optical observations and photometric evidence of supernova
  14. Fermi-LAT Gamma-ray Observations of IceCube-211117A
  15. GRB211118A: Swift/BAT-GUANO detection outside the coded FOV
  16. Fermi trigger No 658971499: Global MASTER-Net observations report
  17. Search for counterpart to IceCube-211117A with ANTARES
  18. IceCube-211117A : IceCube observation of a high-energy neutrino candidate track-like event
  19. IceCube-211116A: Upper limits from a search for additional neutrino events in IceCube
  20. Fermi-LAT Gamma-ray Observations of IceCube-211116A
  21. IceCube-211116A: No neutrino counterpart detected with ANTARES
  22. IceCube Alert 211116.44: Global MASTER-Net observations report
  23. Fermi trigger No 658755664: Global MASTER-Net observations report
  24. Fermi trigger No 658764238: Global MASTER-Net observations report
  25. Konus-Wind detection of GRB 211107B
  26. IceCube-211116A : IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 211115A: CALET Gamma-Ray Burst Monitor detection
  28. Fermi trigger No 658686687: Global MASTER-Net observations report
  29. GRB 211115A: MAXI/GSC detection
  30. GRB 211023A: classification and SPI-ACS/INTEGRAL registration
  31. Fermi GRB 211112A: Global MASTER-Net observations report
  32. GRB 211106A: Swift/UVOT upper limits
  33. IPN triangulation of GRB 211106A (short)
  34. GRB 211112A: Fermi GBM Final Real-time Localization
  35. GRB 211110A: AstroSat CZTI detection
  36. Short GRB 211106A: spectroscopy of galaxies in the field
  37. GRB 211110A: GECAM detection
  38. Fermi trigger No 658214822: Global MASTER-Net observations report
  39. GRB 211107B: Swift-XRT afterglow detection
  40. GRB 211107A: GECAM detection
  41. GRB 211106A: VLT/FORS2 optical observations
  42. GRB 211106A, GROND observations
  43. GRB 211106A: Swift-XRT afterglow detection
  44. Fermi GRB 211109B: Global MASTER-Net observations report
  45. GRB 211023A: SAO RAS optical observations
  46. GRB 211107B: Swift-XRT observations
  47. MeerLICHT follow-up of GRB 211106A
  48. GRB 211109C: GECAM detection
  49. GRB 211107B: Swift ToO observations
  50. GRB 211109B: Fermi GBM Final Real-time Localization
  51. Fermi GRB 211109A: Global MASTER-Net observations report
  52. GRB 211109A: Fermi GBM Final Real-time Localization
  53. GRB 211107B: Swift/BAT detection
  54. GRB 211023A: A BdHN of type I
  55. Fermi GBM Sub-Threshold Detection of GRB 211106A
  56. Konus-Wind detection of GRB 211106A
  57. GRB 211023A: BTA spectroscopic redshift
  58. GRB 211107A: Fermi GBM Final Real-time Localization
  59. GRB 211106A: Swift-XRT observations
  60. GRB 211106A: Swift ToO observations
  61. GRB 211106A: Swift/BAT-GUANO candidate arcminute localization of a short burst
  62. GRB 211105A: MASTER optical inspection
  63. GRB 211105A: Swift/BAT-GUANO detection outside the coded FOV
  64. GRB 211105A: GECAM detection
  65. Swift Trigger 1082569 is probably not a GRB
  66. GRB 211105A: AGILE detection of a burst
  67. Fermi GBM trigger 657780594/211105201 is not a GRB
  68. GRB 211023A: optical detection by SBT in Ondrejov
  69. GRB 211023A: continued 1.3m DFOT Optical Observations and possible jet break
  70. Fermi trigger No 657742914: Global MASTER-Net observations report
  71. GRB 211104A: Fermi GBM Final Real-time Localization
  72. GRB 211023B: Subaru optical observation
  73. GRB 211024A: MITSuME Akeno optical observation
  74. GCN Viewer Now Available
  75. GRB 211102B: GECAM detection
  76. Fermi GRB 211102A: Global MASTER-Net observations report
  77. GRB 211102B: BALROG localization (Fermi Trigger 657554740 / GRB 211102587)
  78. GRB 211102B: Fermi GBM Final Real-time Localization
  79. GRB 211023B: MITSuME Akeno optical upper limits
  80. GRB 211102A: BALROG localization (Fermi Trigger 657533168 / GRB 211102338)
  81. GRB 211102A: Fermi GBM Final Real-time Localization
  82. GRB 211024B: Optical afterglow observation by Ondrejov D50
  83. GRB 211024A: 1.3m DFOT observations
  84. Fermi GRB 211031A: Global MASTER-Net observations report
  85. GRB 211031A: Fermi GBM Final Real-time Localization
  86. IPN triangulation of GRB 211022A
  87. GRB 211023A: 1.3m DFOT Optical Observations
  88. Konus-Wind detection of GRB 211023A
  89. GRB 2121023B: 6 GHz VLA radio upper limit
  90. GRB 211023A: Terskol optical observations
  91. AMON NuEm-211020A: No Candidate Counterparts from Swift-XRT follow up observations
  92. GRB 211023A: continued Mondy optical observations
  93. GRB 211024A: Swift-XRT source 4 is not an afterglow.
  94. GRB 211023B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  95. Fermi GRB 211027A: Global MASTER-Net observations report
  96. GRB 211024A: Possible afterglow candidate from GIT
  97. GRB 211024A: Swift-XRT observations
  98. GRB 211027A: Fermi GBM Final Real-time Localization
  99. GRB 211024A: Fermi GBM detection
  100. GRB 211018A: Swift-XRT observations

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