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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 220304A Fermi GBM detection
  2. IceCube-220306A: Upper limits from a search for additional neutrino events in IceCube
  3. IceCube-220304A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 220306B: Swift-BAT refined analysis
  5. Fermi-LAT Gamma-ray Observations of IceCube-220306A
  6. GRB 220306B: AbAO optical observations, possible afterglow candidate
  7. GRB 220306B: BOOTES-1 optical upper limit
  8. GRB 220306B: Swift-XRT refined Analysis
  9. GRB 220306B: Fermi GBM observation
  10. Fermi-LAT Gamma-ray Observations of IceCube-220304A
  11. GRB 220306B: Enhanced Swift-XRT position
  12. Swift GRB 220306B: Global MASTER-Net observations report
  13. GRB 220305A: Swift-BAT refined analysis
  14. GRB 220306B: Swift detection of a burst
  15. Fermi GBM Sub-Threshold Detection of GRB 220305A
  16. GRB 220305A: Swift-XRT refined Analysis
  17. Fermi GRB 220306A: Global MASTER-Net observations report
  18. GRB 220306A: Fermi GBM Final Real-time Localization
  19. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  20. Fermi GRB 220305A: Global MASTER-Net observations report
  21. Correction to GCN 31689: Fermi GBM Report of GRB 220305A should be GRB 220305B
  22. GRB 220305A: Fermi GBM observation
  23. GRB 220305A: Enhanced Swift-XRT position
  24. IceCube-220303A: One X-ray counterpart from Swift/XRT follow up observations
  25. Swift GRB 220305A: Global MASTER-Net observations report
  26. GRB 220305A: Swift-XRT observations
  27. GRB 220305A: Swift detection of a burst
  28. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, SN signature search
  29. GRB 220302A: Swift/UVOT Upper Limits
  30. IceCube-220303A: Upper limits from a search for additional neutrino events in IceCube
  31. Fermi-LAT Gamma-ray Observations of IceCube-220303A
  32. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  33. IceCube Alert 220304.74: Global MASTER-Net observations report
  34. GRB 220304A: Swift/BAT-GUANO detection outside the coded FOV
  35. Fermi GRB 220304A: Global MASTER-Net observations report
  36. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  37. GRB 220304A: BALROG localization (Fermi Trigger / GRB 220304228)
  38. GRB 220302A: Swift-XRT refined Analysis
  39. GRB 220304A: Fermi GBM Final Real-time Localization
  40. IceCube Alert 220303.75: Global MASTER-Net observations report
  41. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  42. GRB 220302A: BOOTES-5/JGT optical upper limit
  43. Swift resumes autonomous slewing
  44. ZTF22aaajecp/AT2022cmc: AMI-LA radio detection
  45. GRB 220302A: Enhanced Swift-XRT position
  46. ZTF22aaajecp/AT2022cmc: ATCA detection
  47. GRB 220302A: Swift afterglow detection
  48. GRB 220222A: CALET Gamma-Ray Burst Monitor detection
  49. Swift GRB 220302A: Global MASTER-Net observations report
  50. GRB 220302A: Swift detection of a burst
  51. GRB 220228A: Fermi GBM observation
  52. GRB 220228A: Fermi-LAT detection
  53. GRB 220228A: Fermi GBM Final Localization
  54. Konus-Wind detection of GRB 220222A
  55. IceCube-220225A: Upper limits from a search for additional neutrino events in IceCube
  56. Fermi trigger No 667737010: Global MASTER-Net observations report
  57. ZTF22aaajecp/AT2022cmc: JCMT SCUBA-2 sub-mm observations
  58. Fermi-LAT Gamma-ray Observations of IceCube-220225A
  59. ZTF22aaajecp/AT2022cmc: Mondy optical observations
  60. IceCube Alert 220225.59: Global MASTER-Net observations report
  61. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  62. IPN triangulation of GRB 220222A
  63. GRB 220101A: The first example of a Petanova
  64. ZTF22aaajecp/AT2022cmc: DECam Photometry
  65. Konus-Wind observation of GRB 220219B
  66. GCN Circ.draft on GRB 220222A
  67. GRB 220219B: Swift-XRT observations
  68. ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
  69. Fermi GRB 220223A: Global MASTER-Net observations report
  70. ZTF22aaajecp/AT2022cmc: Swift Observation and a UV Detection
  71. GRB 220223A: Fermi GBM Final Real-time Localization
  72. ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
  73. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  74. Fermi GRB 220222B: Global MASTER-Net observations report
  75. GRB 220222B: Fermi GBM Final Real-time Localization
  76. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  77. GRB 220219B: Swift ToO observations
  78. GRB 220222A: Swift/BAT-GUANO detection outside the coded FOV
  79. Fermi-LAT Gamma-ray Observations of IceCube-220221A
  80. Fermi GRB 220222A: Global MASTER-Net observations report
  81. GRB 220222A: Fermi GBM Final Real-time Localization
  82. ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
  83. ZTF22aabjpxh/AT2022cva: Assy optical observations
  84. ZTF22aaajecb/AT2022cmc: Submillimeter Array detection
  85. ZTF22aaajecb/AT 2022cmc: CAHA 2.2m/CAFOS detection, luminous transient
  86. ZTF22aaajecp/AT2022cmc: Terskol observatory optical observations
  87. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  88. IceCube Alert 220221.03: Global MASTER-Net observations report
  89. Konus-Wind observation of GRB 220219A
  90. IPN triangulation of GRB 220219A
  91. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  92. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  93. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  94. Fermi Gamma-ray Burst Monitor trigger 667074291/220220767 is not a GRB
  95. IceCube Alert 220220.60: Global MASTER-Net observations report
  96. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220220A
  97. Fermi trigger No 666962499: Global MASTER-Net observations report
  98. GRB 220218A: BOOTES-5/JGT optical upper limit
  99. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  100. GRB 220219A: AGILE/MCAL detection

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