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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-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  2. IceCube Alert 220304.74: Global MASTER-Net observations report
  3. GRB 220304A: Swift/BAT-GUANO detection outside the coded FOV
  4. Fermi GRB 220304A: Global MASTER-Net observations report
  5. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  6. GRB 220304A: BALROG localization (Fermi Trigger / GRB 220304228)
  7. GRB 220302A: Swift-XRT refined Analysis
  8. GRB 220304A: Fermi GBM Final Real-time Localization
  9. IceCube Alert 220303.75: Global MASTER-Net observations report
  10. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  11. GRB 220302A: BOOTES-5/JGT optical upper limit
  12. Swift resumes autonomous slewing
  13. ZTF22aaajecp/AT2022cmc: AMI-LA radio detection
  14. GRB 220302A: Enhanced Swift-XRT position
  15. ZTF22aaajecp/AT2022cmc: ATCA detection
  16. GRB 220302A: Swift afterglow detection
  17. GRB 220222A: CALET Gamma-Ray Burst Monitor detection
  18. Swift GRB 220302A: Global MASTER-Net observations report
  19. GRB 220302A: Swift detection of a burst
  20. GRB 220228A: Fermi GBM observation
  21. GRB 220228A: Fermi-LAT detection
  22. GRB 220228A: Fermi GBM Final Localization
  23. Konus-Wind detection of GRB 220222A
  24. IceCube-220225A: Upper limits from a search for additional neutrino events in IceCube
  25. Fermi trigger No 667737010: Global MASTER-Net observations report
  26. ZTF22aaajecp/AT2022cmc: JCMT SCUBA-2 sub-mm observations
  27. Fermi-LAT Gamma-ray Observations of IceCube-220225A
  28. ZTF22aaajecp/AT2022cmc: Mondy optical observations
  29. IceCube Alert 220225.59: Global MASTER-Net observations report
  30. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  31. IPN triangulation of GRB 220222A
  32. GRB 220101A: The first example of a Petanova
  33. ZTF22aaajecp/AT2022cmc: DECam Photometry
  34. Konus-Wind observation of GRB 220219B
  35. GCN Circ.draft on GRB 220222A
  36. GRB 220219B: Swift-XRT observations
  37. ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
  38. Fermi GRB 220223A: Global MASTER-Net observations report
  39. ZTF22aaajecp/AT2022cmc: Swift Observation and a UV Detection
  40. GRB 220223A: Fermi GBM Final Real-time Localization
  41. ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
  42. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  43. Fermi GRB 220222B: Global MASTER-Net observations report
  44. GRB 220222B: Fermi GBM Final Real-time Localization
  45. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  46. GRB 220219B: Swift ToO observations
  47. GRB 220222A: Swift/BAT-GUANO detection outside the coded FOV
  48. Fermi-LAT Gamma-ray Observations of IceCube-220221A
  49. Fermi GRB 220222A: Global MASTER-Net observations report
  50. GRB 220222A: Fermi GBM Final Real-time Localization
  51. ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
  52. ZTF22aabjpxh/AT2022cva: Assy optical observations
  53. ZTF22aaajecb/AT2022cmc: Submillimeter Array detection
  54. ZTF22aaajecb/AT 2022cmc: CAHA 2.2m/CAFOS detection, luminous transient
  55. ZTF22aaajecp/AT2022cmc: Terskol observatory optical observations
  56. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  57. IceCube Alert 220221.03: Global MASTER-Net observations report
  58. Konus-Wind observation of GRB 220219A
  59. IPN triangulation of GRB 220219A
  60. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  61. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  62. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  63. Fermi Gamma-ray Burst Monitor trigger 667074291/220220767 is not a GRB
  64. IceCube Alert 220220.60: Global MASTER-Net observations report
  65. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220220A
  66. Fermi trigger No 666962499: Global MASTER-Net observations report
  67. GRB 220218A: BOOTES-5/JGT optical upper limit
  68. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  69. GRB 220219A: AGILE/MCAL detection
  70. GRB 220219A: BALROG localization (Fermi Trigger / GRB 220219473)
  71. GRB 220219A: Fermi GBM Final Real-time Localization
  72. GRB 220218A: Swift detection of a burst
  73. Swift GRB220218.94: Global MASTER-Net observations report
  74. GRB 220211A: redshift lower limit estimating
  75. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory continued optical observations
  76. Konus-Wind detection of GRB 220209A
  77. Swift resumes pointed science observations
  78. ZTF22aaajecp/AT2022cmc: VLT/X-shooter redshift
  79. ZTF22aaajecp/AT2022cmc: NICER X-ray detection
  80. GRB 220211A: MASTER optical observations of ZTF22aaajecp/AT2022cmc
  81. Konus-Wind detection of GRB 220211A
  82. IPN triangulation of GRB 220209A
  83. ZTF22aaajecp: GIT optical follow-up observations
  84. GRB 211023A: evidence of supernova in LBT spectra
  85. ZTF22aaajecp/AT2022cmc: GMOS-N spectroscopy
  86. ZTF22aaajecp/AT2022cmc: Liverpool Telescope photometry
  87. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory optical observations
  88. ZTF22aaajecp/AT2022cmc: VLA radio detection
  89. GRB 220211A: Fermi GBM observation
  90. ZTF22aaajecp/AT2022cmc: Zwicky Transient Facility discovery of a fast and red optical transient
  91. Fermi trigger No 666489765: Global MASTER-Net observations report
  92. GRB 220214A: Fermi GBM Final Real-time Localization
  93. Fermi GBM trigger 666393834/220212892 is not a GRB
  94. GRB 220210A: Mondy, AbAO and Terskol optical upper limits
  95. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220212A
  96. IPN triangulation of GRB 220211A (short)
  97. GRB 220210A: Insight-HXMT/HE detection
  98. GRB 220211A: Swift/BAT-GUANO detection outside the coded FOV (short)
  99. GRB 220210A: 1.5m OSN optical upper limit
  100. GRB 220210A: Fermi GBM detection

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