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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 220305A: Enhanced Swift-XRT position
  2. IceCube-220303A: One X-ray counterpart from Swift/XRT follow up observations
  3. Swift GRB 220305A: Global MASTER-Net observations report
  4. GRB 220305A: Swift-XRT observations
  5. GRB 220305A: Swift detection of a burst
  6. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, SN signature search
  7. GRB 220302A: Swift/UVOT Upper Limits
  8. IceCube-220303A: Upper limits from a search for additional neutrino events in IceCube
  9. Fermi-LAT Gamma-ray Observations of IceCube-220303A
  10. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  11. IceCube Alert 220304.74: Global MASTER-Net observations report
  12. GRB 220304A: Swift/BAT-GUANO detection outside the coded FOV
  13. Fermi GRB 220304A: Global MASTER-Net observations report
  14. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  15. GRB 220304A: BALROG localization (Fermi Trigger / GRB 220304228)
  16. GRB 220302A: Swift-XRT refined Analysis
  17. GRB 220304A: Fermi GBM Final Real-time Localization
  18. IceCube Alert 220303.75: Global MASTER-Net observations report
  19. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  20. GRB 220302A: BOOTES-5/JGT optical upper limit
  21. Swift resumes autonomous slewing
  22. ZTF22aaajecp/AT2022cmc: AMI-LA radio detection
  23. GRB 220302A: Enhanced Swift-XRT position
  24. ZTF22aaajecp/AT2022cmc: ATCA detection
  25. GRB 220302A: Swift afterglow detection
  26. GRB 220222A: CALET Gamma-Ray Burst Monitor detection
  27. Swift GRB 220302A: Global MASTER-Net observations report
  28. GRB 220302A: Swift detection of a burst
  29. GRB 220228A: Fermi GBM observation
  30. GRB 220228A: Fermi-LAT detection
  31. GRB 220228A: Fermi GBM Final Localization
  32. Konus-Wind detection of GRB 220222A
  33. IceCube-220225A: Upper limits from a search for additional neutrino events in IceCube
  34. Fermi trigger No 667737010: Global MASTER-Net observations report
  35. ZTF22aaajecp/AT2022cmc: JCMT SCUBA-2 sub-mm observations
  36. Fermi-LAT Gamma-ray Observations of IceCube-220225A
  37. ZTF22aaajecp/AT2022cmc: Mondy optical observations
  38. IceCube Alert 220225.59: Global MASTER-Net observations report
  39. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  40. IPN triangulation of GRB 220222A
  41. GRB 220101A: The first example of a Petanova
  42. ZTF22aaajecp/AT2022cmc: DECam Photometry
  43. Konus-Wind observation of GRB 220219B
  44. GCN Circ.draft on GRB 220222A
  45. GRB 220219B: Swift-XRT observations
  46. ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
  47. Fermi GRB 220223A: Global MASTER-Net observations report
  48. ZTF22aaajecp/AT2022cmc: Swift Observation and a UV Detection
  49. GRB 220223A: Fermi GBM Final Real-time Localization
  50. ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
  51. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  52. Fermi GRB 220222B: Global MASTER-Net observations report
  53. GRB 220222B: Fermi GBM Final Real-time Localization
  54. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  55. GRB 220219B: Swift ToO observations
  56. GRB 220222A: Swift/BAT-GUANO detection outside the coded FOV
  57. Fermi-LAT Gamma-ray Observations of IceCube-220221A
  58. Fermi GRB 220222A: Global MASTER-Net observations report
  59. GRB 220222A: Fermi GBM Final Real-time Localization
  60. ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
  61. ZTF22aabjpxh/AT2022cva: Assy optical observations
  62. ZTF22aaajecb/AT2022cmc: Submillimeter Array detection
  63. ZTF22aaajecb/AT 2022cmc: CAHA 2.2m/CAFOS detection, luminous transient
  64. ZTF22aaajecp/AT2022cmc: Terskol observatory optical observations
  65. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  66. IceCube Alert 220221.03: Global MASTER-Net observations report
  67. Konus-Wind observation of GRB 220219A
  68. IPN triangulation of GRB 220219A
  69. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  70. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  71. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  72. Fermi Gamma-ray Burst Monitor trigger 667074291/220220767 is not a GRB
  73. IceCube Alert 220220.60: Global MASTER-Net observations report
  74. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220220A
  75. Fermi trigger No 666962499: Global MASTER-Net observations report
  76. GRB 220218A: BOOTES-5/JGT optical upper limit
  77. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  78. GRB 220219A: AGILE/MCAL detection
  79. GRB 220219A: BALROG localization (Fermi Trigger / GRB 220219473)
  80. GRB 220219A: Fermi GBM Final Real-time Localization
  81. GRB 220218A: Swift detection of a burst
  82. Swift GRB220218.94: Global MASTER-Net observations report
  83. GRB 220211A: redshift lower limit estimating
  84. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory continued optical observations
  85. Konus-Wind detection of GRB 220209A
  86. Swift resumes pointed science observations
  87. ZTF22aaajecp/AT2022cmc: VLT/X-shooter redshift
  88. ZTF22aaajecp/AT2022cmc: NICER X-ray detection
  89. GRB 220211A: MASTER optical observations of ZTF22aaajecp/AT2022cmc
  90. Konus-Wind detection of GRB 220211A
  91. IPN triangulation of GRB 220209A
  92. ZTF22aaajecp: GIT optical follow-up observations
  93. GRB 211023A: evidence of supernova in LBT spectra
  94. ZTF22aaajecp/AT2022cmc: GMOS-N spectroscopy
  95. ZTF22aaajecp/AT2022cmc: Liverpool Telescope photometry
  96. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory optical observations
  97. ZTF22aaajecp/AT2022cmc: VLA radio detection
  98. GRB 220211A: Fermi GBM observation
  99. ZTF22aaajecp/AT2022cmc: Zwicky Transient Facility discovery of a fast and red optical transient
  100. Fermi trigger No 666489765: Global MASTER-Net observations report

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