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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. IPN triangulation of GRB 220222A
  2. GRB 220101A: The first example of a Petanova
  3. ZTF22aaajecp/AT2022cmc: DECam Photometry
  4. Konus-Wind observation of GRB 220219B
  5. GCN Circ.draft on GRB 220222A
  6. GRB 220219B: Swift-XRT observations
  7. ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
  8. Fermi GRB 220223A: Global MASTER-Net observations report
  9. ZTF22aaajecp/AT2022cmc: Swift Observation and a UV Detection
  10. GRB 220223A: Fermi GBM Final Real-time Localization
  11. ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
  12. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  13. Fermi GRB 220222B: Global MASTER-Net observations report
  14. GRB 220222B: Fermi GBM Final Real-time Localization
  15. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  16. GRB 220219B: Swift ToO observations
  17. GRB 220222A: Swift/BAT-GUANO detection outside the coded FOV
  18. Fermi-LAT Gamma-ray Observations of IceCube-220221A
  19. Fermi GRB 220222A: Global MASTER-Net observations report
  20. GRB 220222A: Fermi GBM Final Real-time Localization
  21. ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
  22. ZTF22aabjpxh/AT2022cva: Assy optical observations
  23. ZTF22aaajecb/AT2022cmc: Submillimeter Array detection
  24. ZTF22aaajecb/AT 2022cmc: CAHA 2.2m/CAFOS detection, luminous transient
  25. ZTF22aaajecp/AT2022cmc: Terskol observatory optical observations
  26. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  27. IceCube Alert 220221.03: Global MASTER-Net observations report
  28. Konus-Wind observation of GRB 220219A
  29. IPN triangulation of GRB 220219A
  30. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  31. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  32. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  33. Fermi Gamma-ray Burst Monitor trigger 667074291/220220767 is not a GRB
  34. IceCube Alert 220220.60: Global MASTER-Net observations report
  35. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220220A
  36. Fermi trigger No 666962499: Global MASTER-Net observations report
  37. GRB 220218A: BOOTES-5/JGT optical upper limit
  38. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  39. GRB 220219A: AGILE/MCAL detection
  40. GRB 220219A: BALROG localization (Fermi Trigger / GRB 220219473)
  41. GRB 220219A: Fermi GBM Final Real-time Localization
  42. GRB 220218A: Swift detection of a burst
  43. Swift GRB220218.94: Global MASTER-Net observations report
  44. GRB 220211A: redshift lower limit estimating
  45. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory continued optical observations
  46. Konus-Wind detection of GRB 220209A
  47. Swift resumes pointed science observations
  48. ZTF22aaajecp/AT2022cmc: VLT/X-shooter redshift
  49. ZTF22aaajecp/AT2022cmc: NICER X-ray detection
  50. GRB 220211A: MASTER optical observations of ZTF22aaajecp/AT2022cmc
  51. Konus-Wind detection of GRB 220211A
  52. IPN triangulation of GRB 220209A
  53. ZTF22aaajecp: GIT optical follow-up observations
  54. GRB 211023A: evidence of supernova in LBT spectra
  55. ZTF22aaajecp/AT2022cmc: GMOS-N spectroscopy
  56. ZTF22aaajecp/AT2022cmc: Liverpool Telescope photometry
  57. ZTF22aaajecp/AT2022cmc: Zeiss-1000 of Koshka observatory optical observations
  58. ZTF22aaajecp/AT2022cmc: VLA radio detection
  59. GRB 220211A: Fermi GBM observation
  60. ZTF22aaajecp/AT2022cmc: Zwicky Transient Facility discovery of a fast and red optical transient
  61. Fermi trigger No 666489765: Global MASTER-Net observations report
  62. GRB 220214A: Fermi GBM Final Real-time Localization
  63. Fermi GBM trigger 666393834/220212892 is not a GRB
  64. GRB 220210A: Mondy, AbAO and Terskol optical upper limits
  65. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220212A
  66. IPN triangulation of GRB 220211A (short)
  67. GRB 220210A: Insight-HXMT/HE detection
  68. GRB 220211A: Swift/BAT-GUANO detection outside the coded FOV (short)
  69. GRB 220210A: 1.5m OSN optical upper limit
  70. GRB 220210A: Fermi GBM detection
  71. Fermi GRB 220211B: Global MASTER-Net observations report
  72. GRB 220211B: Fermi GBM Final Real-time Localization
  73. GRB 220209A: Fermi-LAT detection
  74. GRB 220210A: Fermi-LAT detection
  75. GRB 220210A: AGILE detection
  76. GRB 220210A: BOOTES-5/JGT optical afterglow candidate discarded
  77. GRB 220210A: BOOTES-5/JGT optical afterglow candidate
  78. GRB 220210A: Swift/BAT-GUANO localization
  79. Fermi GRB 220211A: Global MASTER-Net observations report
  80. GRB 220211A: Fermi GBM Final Real-time Localization
  81. Fermi GRB 220210A: Global MASTER-Net observations report
  82. GRB 220210A: Fermi GBM Final Real-time Localization
  83. GRB 210919A: Maidanak optical observations
  84. GRB 210919A: SPI-ACS/INTEGRAL observation and evaluation of Ep
  85. GRB 220209A: Fermi GBM Detection
  86. GRB 220209A: GECAM detection
  87. GRB 220209A: AGILE/MCAL detection
  88. Fermi GRB 220209A: Global MASTER-Net observations report
  89. GRB 220209A: Fermi GBM Final Real-time Localization
  90. IceCube-220205B: Upper limits from a search for additional neutrino events in IceCube
  91. IceCube-220205A: Upper limits from a search for additional neutrino events in IceCube
  92. Fermi-LAT Gamma-ray Observations of IceCube-220205B
  93. Fermi-LAT Gamma-ray Observations of IceCube-220205A
  94. IceCube-220205B: No neutrino counterpart candidates in ANTARES search
  95. Konus-Wind detection of GRB 220130A
  96. IceCube-220205B - IceCube observation of a high-energy neutrino candidate track-like event
  97. Konus-Wind detection of GRB 220203A
  98. GRB 220203A: GECAM detection
  99. IceCube-220205A - IceCube observation of a high-energy neutrino candidate track-like event
  100. GRB 220203A: Swift/BAT-GUANO detection outside the coded FOV

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