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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 GRB 220306A: Global MASTER-Net observations report
  2. GRB 220306A: Fermi GBM Final Real-time Localization
  3. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  4. Fermi GRB 220305A: Global MASTER-Net observations report
  5. Correction to GCN 31689: Fermi GBM Report of GRB 220305A should be GRB 220305B
  6. GRB 220305A: Fermi GBM observation
  7. GRB 220305A: Enhanced Swift-XRT position
  8. IceCube-220303A: One X-ray counterpart from Swift/XRT follow up observations
  9. Swift GRB 220305A: Global MASTER-Net observations report
  10. GRB 220305A: Swift-XRT observations
  11. GRB 220305A: Swift detection of a burst
  12. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, SN signature search
  13. GRB 220302A: Swift/UVOT Upper Limits
  14. IceCube-220303A: Upper limits from a search for additional neutrino events in IceCube
  15. Fermi-LAT Gamma-ray Observations of IceCube-220303A
  16. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  17. IceCube Alert 220304.74: Global MASTER-Net observations report
  18. GRB 220304A: Swift/BAT-GUANO detection outside the coded FOV
  19. Fermi GRB 220304A: Global MASTER-Net observations report
  20. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  21. GRB 220304A: BALROG localization (Fermi Trigger / GRB 220304228)
  22. GRB 220302A: Swift-XRT refined Analysis
  23. GRB 220304A: Fermi GBM Final Real-time Localization
  24. IceCube Alert 220303.75: Global MASTER-Net observations report
  25. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB 220302A: BOOTES-5/JGT optical upper limit
  27. Swift resumes autonomous slewing
  28. ZTF22aaajecp/AT2022cmc: AMI-LA radio detection
  29. GRB 220302A: Enhanced Swift-XRT position
  30. ZTF22aaajecp/AT2022cmc: ATCA detection
  31. GRB 220302A: Swift afterglow detection
  32. GRB 220222A: CALET Gamma-Ray Burst Monitor detection
  33. Swift GRB 220302A: Global MASTER-Net observations report
  34. GRB 220302A: Swift detection of a burst
  35. GRB 220228A: Fermi GBM observation
  36. GRB 220228A: Fermi-LAT detection
  37. GRB 220228A: Fermi GBM Final Localization
  38. Konus-Wind detection of GRB 220222A
  39. IceCube-220225A: Upper limits from a search for additional neutrino events in IceCube
  40. Fermi trigger No 667737010: Global MASTER-Net observations report
  41. ZTF22aaajecp/AT2022cmc: JCMT SCUBA-2 sub-mm observations
  42. Fermi-LAT Gamma-ray Observations of IceCube-220225A
  43. ZTF22aaajecp/AT2022cmc: Mondy optical observations
  44. IceCube Alert 220225.59: Global MASTER-Net observations report
  45. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  46. IPN triangulation of GRB 220222A
  47. GRB 220101A: The first example of a Petanova
  48. ZTF22aaajecp/AT2022cmc: DECam Photometry
  49. Konus-Wind observation of GRB 220219B
  50. GCN Circ.draft on GRB 220222A
  51. GRB 220219B: Swift-XRT observations
  52. ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
  53. Fermi GRB 220223A: Global MASTER-Net observations report
  54. ZTF22aaajecp/AT2022cmc: Swift Observation and a UV Detection
  55. GRB 220223A: Fermi GBM Final Real-time Localization
  56. ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
  57. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  58. Fermi GRB 220222B: Global MASTER-Net observations report
  59. GRB 220222B: Fermi GBM Final Real-time Localization
  60. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  61. GRB 220219B: Swift ToO observations
  62. GRB 220222A: Swift/BAT-GUANO detection outside the coded FOV
  63. Fermi-LAT Gamma-ray Observations of IceCube-220221A
  64. Fermi GRB 220222A: Global MASTER-Net observations report
  65. GRB 220222A: Fermi GBM Final Real-time Localization
  66. ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
  67. ZTF22aabjpxh/AT2022cva: Assy optical observations
  68. ZTF22aaajecb/AT2022cmc: Submillimeter Array detection
  69. ZTF22aaajecb/AT 2022cmc: CAHA 2.2m/CAFOS detection, luminous transient
  70. ZTF22aaajecp/AT2022cmc: Terskol observatory optical observations
  71. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  72. IceCube Alert 220221.03: Global MASTER-Net observations report
  73. Konus-Wind observation of GRB 220219A
  74. IPN triangulation of GRB 220219A
  75. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  76. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  77. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  78. Fermi Gamma-ray Burst Monitor trigger 667074291/220220767 is not a GRB
  79. IceCube Alert 220220.60: Global MASTER-Net observations report
  80. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220220A
  81. Fermi trigger No 666962499: Global MASTER-Net observations report
  82. GRB 220218A: BOOTES-5/JGT optical upper limit
  83. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  84. GRB 220219A: AGILE/MCAL detection
  85. GRB 220219A: BALROG localization (Fermi Trigger / GRB 220219473)
  86. GRB 220219A: Fermi GBM Final Real-time Localization
  87. GRB 220218A: Swift detection of a burst
  88. Swift GRB220218.94: Global MASTER-Net observations report
  89. GRB 220211A: redshift lower limit estimating
  90. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory continued optical observations
  91. Konus-Wind detection of GRB 220209A
  92. Swift resumes pointed science observations
  93. ZTF22aaajecp/AT2022cmc: VLT/X-shooter redshift
  94. ZTF22aaajecp/AT2022cmc: NICER X-ray detection
  95. GRB 220211A: MASTER optical observations of ZTF22aaajecp/AT2022cmc
  96. Konus-Wind detection of GRB 220211A
  97. IPN triangulation of GRB 220209A
  98. ZTF22aaajecp: GIT optical follow-up observations
  99. GRB 211023A: evidence of supernova in LBT spectra
  100. ZTF22aaajecp/AT2022cmc: GMOS-N spectroscopy

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