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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 221203A: Fermi GBM Final Real-time Localization
  2. GRB 221201A: Fermi GBM observation
  3. GRB 221202A: Swift-XRT refined Analysis
  4. GRB 221202A: LCOGT Optical Upper Limits
  5. GRB 221202A: Enhanced Swift-XRT position
  6. GRB 221202A: MeerLICHT upper limits
  7. GRB 221202B: Fermi GBM Final Real-time Localization
  8. GRB 221202A: Swift detection of a burst
  9. Swift GRB221202.84: Global MASTER-Net observations report
  10. GCN: GRB 221201A: Swift/UVOT Upper Limits
  11. GRB 221201A: Swift-XRT refined Analysis
  12. GRB 221201A: Enhanced Swift-XRT position
  13. Swift GRB 221201A: Global MASTER-Net observations report
  14. Konus-Wind detection of GRB 221124A
  15. GRB 221201A: Swift detection of a burst
  16. GRB 221201A: Fermi GBM Final Real-time Localization
  17. Fermi Gamma-ray Burst Monitor trigger 691534074/221130867 is not a GRB
  18. Optical polarization observation of GRB 221009A
  19. GRB 221126A: Fermi GBM observation
  20. IceCube-221124A: Upper limits from a search for additional neutrino events in IceCube
  21. GRB 221126A: AGILE detection
  22. GRB 221127A: Detection by GRBAlpha
  23. GRB 221126A: AstroSat CZTI detection
  24. IceCube-221124A: BOOTES-4/MET and BOOTES-2/TELMA optical upper limit
  25. Alert from the HAWC Burst Monitor HAWC-221128A
  26. GRB 221126A: Swift/BAT-GUANO detection outside the coded FOV
  27. IPN triangulation of GRB 221124A (long)
  28. GRB 221126A: Fermi GBM Final Real-time Localization
  29. GRB 221124A: Swift/BAT-GUANO detection
  30. Fermi-LAT gamma-ray observations of IceCube-221124A
  31. GRB 221120A: Detection by VZLUSAT-2
  32. GRB 221124A: CALET Gamma-Ray Burst Monitor detection
  33. IceCube-221124A - IceCube observation of a high-energy neutrino candidate track-like event
  34. IceCube Alert 221124.66: Global MASTER-Net observations report
  35. GRB 221120A: TURBO Optical Upper Limit
  36. GRB 221122A: Detection by GRBAlpha
  37. GRB 221120A: VIRT Optical Upper Limit
  38. Alert from the HAWC Burst Monitor HAWC-221123A
  39. GRB 221121A: CALET Gamma-Ray Burst Monitor detection
  40. GRB 221009A：DAMPE observed a 34.7 GeV photon at 1.36 hour after the GBM trigger
  41. GRB 221120A: GTC Confirmation of an Underlying Galaxy
  42. IPN triangulation of GRB 221121A (long)
  43. GRB 221120A: Swift-BAT refined analysis
  44. GRB221121A: AstroSat CZTI detection
  45. GRB 221120A: AKO Telescope Upper Limits
  46. GRB221120A: WIRC near-IR imaging of the afterglow candidate
  47. GRB 221120A: Liverpool Telescope Upper Limits
  48. GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
  49. GRB 221120A: Fermi GBM observation
  50. GRB 221120A: Swift-XRT refined Analysis
  51. GRB 221120A: Enhanced Swift-XRT position
  52. GRB221120A: Montarrenti Observatory Upper Limit
  53. GRB 221121A: Fermi GBM Final Real-time Localization
  54. GRB 221120A is a short burst
  55. GRB 221120A: Swift/UVOT Upper Limits
  56. GRB 221120A: LDT Optical Afterglow Candidate
  57. GRB 221120A: GIT upper limits on optical afterglow
  58. GRB 221120A: Swift detection of a likely short burst
  59. GRB 221119A: Fermi GBM detection
  60. GRB 221119A: Detection by GRBAlpha
  61. GRB 221119A: Fermi-LAT detection
  62. LAT GRB221119.63: Global MASTER-Net observations report
  63. GRB 221119A: Fermi GBM Final Real-time Localization
  64. GRB 221009A: Japanese VLBI Network observation
  65. GRB 221115B: CALET Gamma-Ray Burst Monitor detection
  66. GRB 221114A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 221118A: Fermi GBM Final Real-time Localization
  68. GRB 221115B: LCOGT Optical Upper Limits
  69. Correction to GCN 32646 (GRB 221009A (Swift J1913.1+1946): MeerLICHT observations)
  70. GRB 221115B : MeerLICHT upper limits
  71. GRB 221115A: Fermi GBM detection
  72. GRB 221115B: Swift/BAT-GUANO arcminute localization
  73. GRB 221115A: Swift/BAT-GUANO detection
  74. GRB 221110A: GRANDMA observations
  75. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 November 9
  76. GRB 221112A: Detection by GRBAlpha
  77. GRB 221112A: Fermi GBM Final Real-time Localization
  78. GRB 221110A: COATLI Second-Epoch Upper Limits
  79. GRB 221009A: GRANDMA/Kilonova-Catcher observations
  80. GRB 221110A: GMG upper limit
  81. GRB 221110A: Swift/UVOT Detection and Corrected UVOT Position
  82. GRB 221110A: Swift-BAT refined analysis
  83. GRB 221110A: Swift-XRT refined Analysis
  84. GRB 221110A: Enhanced Swift-XRT position
  85. GRB 221110A: VLT/X-shooter redshift
  86. GRB 221110A: COATLI Afterglow detection
  87. GRB 221110A: LCOGT Optical Afterglow Detection
  88. GRB 221110A: Swift detection of a burst with an optical counterpart
  89. Swift GRB221110.10: Global MASTER-Net OT detection
  90. Swift GRB221110.10: Global MASTER-Net observations report
  91. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  92. GRB 221009A: Hubble Space Telescope observations
  93. GRB 221104A: Fermi GBM Final Localization
  94. GRB 221108A: Fermi GBM Final Localization
  95. GRB 221107A: Fermi GBM Observation
  96. GRB 221107A: Detection by GRBAlpha
  97. GRB 221009A: Extended Bad Time Intervals for Fermi LAT data
  98. GRB 221107A: Swift/BAT-GUANO detection outside the coded FOV
  99. IceCube-221104A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 221107A: Fermi GBM Final Localization

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