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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-220303A: One X-ray counterpart from Swift/XRT follow up observations
  2. Swift GRB 220305A: Global MASTER-Net observations report
  3. GRB 220305A: Swift-XRT observations
  4. GRB 220305A: Swift detection of a burst
  5. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, SN signature search
  6. GRB 220302A: Swift/UVOT Upper Limits
  7. IceCube-220303A: Upper limits from a search for additional neutrino events in IceCube
  8. Fermi-LAT Gamma-ray Observations of IceCube-220303A
  9. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  10. IceCube Alert 220304.74: Global MASTER-Net observations report
  11. GRB 220304A: Swift/BAT-GUANO detection outside the coded FOV
  12. Fermi GRB 220304A: Global MASTER-Net observations report
  13. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  14. GRB 220304A: BALROG localization (Fermi Trigger / GRB 220304228)
  15. GRB 220302A: Swift-XRT refined Analysis
  16. GRB 220304A: Fermi GBM Final Real-time Localization
  17. IceCube Alert 220303.75: Global MASTER-Net observations report
  18. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 220302A: BOOTES-5/JGT optical upper limit
  20. Swift resumes autonomous slewing
  21. ZTF22aaajecp/AT2022cmc: AMI-LA radio detection
  22. GRB 220302A: Enhanced Swift-XRT position
  23. ZTF22aaajecp/AT2022cmc: ATCA detection
  24. GRB 220302A: Swift afterglow detection
  25. GRB 220222A: CALET Gamma-Ray Burst Monitor detection
  26. Swift GRB 220302A: Global MASTER-Net observations report
  27. GRB 220302A: Swift detection of a burst
  28. GRB 220228A: Fermi GBM observation
  29. GRB 220228A: Fermi-LAT detection
  30. GRB 220228A: Fermi GBM Final Localization
  31. Konus-Wind detection of GRB 220222A
  32. IceCube-220225A: Upper limits from a search for additional neutrino events in IceCube
  33. Fermi trigger No 667737010: Global MASTER-Net observations report
  34. ZTF22aaajecp/AT2022cmc: JCMT SCUBA-2 sub-mm observations
  35. Fermi-LAT Gamma-ray Observations of IceCube-220225A
  36. ZTF22aaajecp/AT2022cmc: Mondy optical observations
  37. IceCube Alert 220225.59: Global MASTER-Net observations report
  38. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  39. IPN triangulation of GRB 220222A
  40. GRB 220101A: The first example of a Petanova
  41. ZTF22aaajecp/AT2022cmc: DECam Photometry
  42. Konus-Wind observation of GRB 220219B
  43. GCN Circ.draft on GRB 220222A
  44. GRB 220219B: Swift-XRT observations
  45. ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
  46. Fermi GRB 220223A: Global MASTER-Net observations report
  47. ZTF22aaajecp/AT2022cmc: Swift Observation and a UV Detection
  48. GRB 220223A: Fermi GBM Final Real-time Localization
  49. ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
  50. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  51. Fermi GRB 220222B: Global MASTER-Net observations report
  52. GRB 220222B: Fermi GBM Final Real-time Localization
  53. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  54. GRB 220219B: Swift ToO observations
  55. GRB 220222A: Swift/BAT-GUANO detection outside the coded FOV
  56. Fermi-LAT Gamma-ray Observations of IceCube-220221A
  57. Fermi GRB 220222A: Global MASTER-Net observations report
  58. GRB 220222A: Fermi GBM Final Real-time Localization
  59. ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
  60. ZTF22aabjpxh/AT2022cva: Assy optical observations
  61. ZTF22aaajecb/AT2022cmc: Submillimeter Array detection
  62. ZTF22aaajecb/AT 2022cmc: CAHA 2.2m/CAFOS detection, luminous transient
  63. ZTF22aaajecp/AT2022cmc: Terskol observatory optical observations
  64. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  65. IceCube Alert 220221.03: Global MASTER-Net observations report
  66. Konus-Wind observation of GRB 220219A
  67. IPN triangulation of GRB 220219A
  68. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  69. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  70. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  71. Fermi Gamma-ray Burst Monitor trigger 667074291/220220767 is not a GRB
  72. IceCube Alert 220220.60: Global MASTER-Net observations report
  73. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220220A
  74. Fermi trigger No 666962499: Global MASTER-Net observations report
  75. GRB 220218A: BOOTES-5/JGT optical upper limit
  76. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  77. GRB 220219A: AGILE/MCAL detection
  78. GRB 220219A: BALROG localization (Fermi Trigger / GRB 220219473)
  79. GRB 220219A: Fermi GBM Final Real-time Localization
  80. GRB 220218A: Swift detection of a burst
  81. Swift GRB220218.94: Global MASTER-Net observations report
  82. GRB 220211A: redshift lower limit estimating
  83. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory continued optical observations
  84. Konus-Wind detection of GRB 220209A
  85. Swift resumes pointed science observations
  86. ZTF22aaajecp/AT2022cmc: VLT/X-shooter redshift
  87. ZTF22aaajecp/AT2022cmc: NICER X-ray detection
  88. GRB 220211A: MASTER optical observations of ZTF22aaajecp/AT2022cmc
  89. Konus-Wind detection of GRB 220211A
  90. IPN triangulation of GRB 220209A
  91. ZTF22aaajecp: GIT optical follow-up observations
  92. GRB 211023A: evidence of supernova in LBT spectra
  93. ZTF22aaajecp/AT2022cmc: GMOS-N spectroscopy
  94. ZTF22aaajecp/AT2022cmc: Liverpool Telescope photometry
  95. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory optical observations
  96. ZTF22aaajecp/AT2022cmc: VLA radio detection
  97. GRB 220211A: Fermi GBM observation
  98. ZTF22aaajecp/AT2022cmc: Zwicky Transient Facility discovery of a fast and red optical transient
  99. Fermi trigger No 666489765: Global MASTER-Net observations report
  100. GRB 220214A: Fermi GBM Final Real-time Localization

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