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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. Fermi-LAT Gamma-ray Observations of IceCube-220306A
  2. GRB 220306B: AbAO optical observations, possible afterglow candidate
  3. GRB 220306B: BOOTES-1 optical upper limit
  4. GRB 220306B: Swift-XRT refined Analysis
  5. GRB 220306B: Fermi GBM observation
  6. Fermi-LAT Gamma-ray Observations of IceCube-220304A
  7. GRB 220306B: Enhanced Swift-XRT position
  8. Swift GRB 220306B: Global MASTER-Net observations report
  9. GRB 220305A: Swift-BAT refined analysis
  10. GRB 220306B: Swift detection of a burst
  11. Fermi GBM Sub-Threshold Detection of GRB 220305A
  12. GRB 220305A: Swift-XRT refined Analysis
  13. Fermi GRB 220306A: Global MASTER-Net observations report
  14. GRB 220306A: Fermi GBM Final Real-time Localization
  15. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  16. Fermi GRB 220305A: Global MASTER-Net observations report
  17. Correction to GCN 31689: Fermi GBM Report of GRB 220305A should be GRB 220305B
  18. GRB 220305A: Fermi GBM observation
  19. GRB 220305A: Enhanced Swift-XRT position
  20. IceCube-220303A: One X-ray counterpart from Swift/XRT follow up observations
  21. Swift GRB 220305A: Global MASTER-Net observations report
  22. GRB 220305A: Swift-XRT observations
  23. GRB 220305A: Swift detection of a burst
  24. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, SN signature search
  25. GRB 220302A: Swift/UVOT Upper Limits
  26. IceCube-220303A: Upper limits from a search for additional neutrino events in IceCube
  27. Fermi-LAT Gamma-ray Observations of IceCube-220303A
  28. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  29. IceCube Alert 220304.74: Global MASTER-Net observations report
  30. GRB 220304A: Swift/BAT-GUANO detection outside the coded FOV
  31. Fermi GRB 220304A: Global MASTER-Net observations report
  32. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  33. GRB 220304A: BALROG localization (Fermi Trigger / GRB 220304228)
  34. GRB 220302A: Swift-XRT refined Analysis
  35. GRB 220304A: Fermi GBM Final Real-time Localization
  36. IceCube Alert 220303.75: Global MASTER-Net observations report
  37. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 220302A: BOOTES-5/JGT optical upper limit
  39. Swift resumes autonomous slewing
  40. ZTF22aaajecp/AT2022cmc: AMI-LA radio detection
  41. GRB 220302A: Enhanced Swift-XRT position
  42. ZTF22aaajecp/AT2022cmc: ATCA detection
  43. GRB 220302A: Swift afterglow detection
  44. GRB 220222A: CALET Gamma-Ray Burst Monitor detection
  45. Swift GRB 220302A: Global MASTER-Net observations report
  46. GRB 220302A: Swift detection of a burst
  47. GRB 220228A: Fermi GBM observation
  48. GRB 220228A: Fermi-LAT detection
  49. GRB 220228A: Fermi GBM Final Localization
  50. Konus-Wind detection of GRB 220222A
  51. IceCube-220225A: Upper limits from a search for additional neutrino events in IceCube
  52. Fermi trigger No 667737010: Global MASTER-Net observations report
  53. ZTF22aaajecp/AT2022cmc: JCMT SCUBA-2 sub-mm observations
  54. Fermi-LAT Gamma-ray Observations of IceCube-220225A
  55. ZTF22aaajecp/AT2022cmc: Mondy optical observations
  56. IceCube Alert 220225.59: Global MASTER-Net observations report
  57. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  58. IPN triangulation of GRB 220222A
  59. GRB 220101A: The first example of a Petanova
  60. ZTF22aaajecp/AT2022cmc: DECam Photometry
  61. Konus-Wind observation of GRB 220219B
  62. GCN Circ.draft on GRB 220222A
  63. GRB 220219B: Swift-XRT observations
  64. ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
  65. Fermi GRB 220223A: Global MASTER-Net observations report
  66. ZTF22aaajecp/AT2022cmc: Swift Observation and a UV Detection
  67. GRB 220223A: Fermi GBM Final Real-time Localization
  68. ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
  69. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  70. Fermi GRB 220222B: Global MASTER-Net observations report
  71. GRB 220222B: Fermi GBM Final Real-time Localization
  72. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  73. GRB 220219B: Swift ToO observations
  74. GRB 220222A: Swift/BAT-GUANO detection outside the coded FOV
  75. Fermi-LAT Gamma-ray Observations of IceCube-220221A
  76. Fermi GRB 220222A: Global MASTER-Net observations report
  77. GRB 220222A: Fermi GBM Final Real-time Localization
  78. ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
  79. ZTF22aabjpxh/AT2022cva: Assy optical observations
  80. ZTF22aaajecb/AT2022cmc: Submillimeter Array detection
  81. ZTF22aaajecb/AT 2022cmc: CAHA 2.2m/CAFOS detection, luminous transient
  82. ZTF22aaajecp/AT2022cmc: Terskol observatory optical observations
  83. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  84. IceCube Alert 220221.03: Global MASTER-Net observations report
  85. Konus-Wind observation of GRB 220219A
  86. IPN triangulation of GRB 220219A
  87. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  88. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  89. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  90. Fermi Gamma-ray Burst Monitor trigger 667074291/220220767 is not a GRB
  91. IceCube Alert 220220.60: Global MASTER-Net observations report
  92. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220220A
  93. Fermi trigger No 666962499: Global MASTER-Net observations report
  94. GRB 220218A: BOOTES-5/JGT optical upper limit
  95. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  96. GRB 220219A: AGILE/MCAL detection
  97. GRB 220219A: BALROG localization (Fermi Trigger / GRB 220219473)
  98. GRB 220219A: Fermi GBM Final Real-time Localization
  99. GRB 220218A: Swift detection of a burst
  100. Swift GRB220218.94: Global MASTER-Net observations report

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