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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 220909A: Fermi GBM Final Real-time Localization
  2. IceCube-220907A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 220907A: Swift-BAT refined analysis
  4. IceCube-220907A: One Candidate Counterpart from the Zwicky Transient Facility
  5. GRB 220831A: Gemini-South/GMOS detection of potential optical counterpart
  6. IPN triangulation of GRB 220903A (long)
  7. GRB 220907A: Fermi GBM observation
  8. GRB 220907A: Nanshan/NEXT optical upper limits
  9. GRB 220907A: Swift/UVOT Upper Limits
  10. GRB 220907A: Swift-XRT refined Analysis
  11. GRB 220831A: ATCA 5/9 GHz radio observations
  12. Fermi-LAT Gamma-ray Observations of IceCube-220907A
  13. GRB 220907A: Swift-XRT position
  14. GRB 220907A: Swift detection of a burst
  15. GRB 220907A: Fermi GBM Final Real-time Localization
  16. Swift GRB220907.59: Global MASTER-Net observations report
  17. IceCube-220907A - IceCube observation of a high-energy neutrino candidate track-like event
  18. IceCube Alert 220907.28: Global MASTER-Net observations report
  19. GRB 220831A: Swift-UVOT Upper Limits
  20. Fermi GRB 220905A: Global MASTER-Net observations report
  21. GRB 220905A: BALROG localization (Fermi Trigger 684070128 / GRB 220905478)
  22. GRB 220905A: Fermi GBM Final Real-time Localization
  23. Introducing Self-Service Configuration of GCN Notices over Email for Transient Alerts
  24. GRB 220831A: DECam detection of a possible optical counterpart
  25. Fermi GRB 220902A: Global MASTER-Net observations report
  26. GRB 220902A: Fermi GBM Final Real-time Localization
  27. GRB 220831A, VLT/HAWK-I near-infrared observations
  28. GRB 220831C: Fermi GBM Final Localization
  29. GRB 220831A: Fermi GBM observation
  30. GRB 220831A: Swift-XRT observations
  31. GRB 220831B: Fermi GBM Final Localization
  32. GRB 220831A: Swift ToO observations
  33. Fermi trigger No 683654200: Global MASTER-Net observations report
  34. GRB 220831A: Swift/BAT-GUANO localization of a short burst
  35. Fermi trigger No 683646997: Global MASTER-Net observations report
  36. IceCube-220822A: No significant detection in HAWC
  37. Fermi trigger No 683537972: Global MASTER-Net observations report
  38. Fermi GBM trigger 683571622/220830709 is not a GRB
  39. Fermi trigger No 683476673: Global MASTER-Net observations report
  40. Konus-Wind detection of GRB 220826A
  41. IceCube-Cascade 220826A: Upper limits from a search for additional neutrino events in IceCube
  42. IceCube-220822A: Classification of AT2022saw as a Type Ia supernova
  43. GRB 220827A: Fermi GBM Final Real-time Localization
  44. GRB 220826A: Swift-BAT refined analysis
  45. GRB 220826A: Fermi GBM observation
  46. Fermi trigger No 683202084: Global MASTER-Net observations report
  47. Fermi trigger No 683183601: Global MASTER-Net observations report
  48. Fermi trigger No 683152759: Global MASTER-Net observations report
  49. GRB 220826A: Swift-XRT refined Analysis
  50. GRB 220825A: Fermi GBM observation
  51. GRB 220826A: Lesedi optical afterglow detection
  52. GRB 220826A: Swift/UVOT Detection
  53. GRB 220826A: iTelescope optical afterglow observations
  54. Swift GRB 220826A: Global MASTER-Net observations report
  55. GRB 220826A: Enhanced Swift-XRT position
  56. GRB 220826A: Swift detection of a burst with an optical counterpart
  57. GRB 220825A: Swift/BAT-GUANO detection
  58. GRB 220825A: Fermi GBM Final Localization
  59. IceCube-220822A: Upper limits from a search for additional neutrino events in IceCube
  60. IceCube-220822A: One Candidate Counterpart from the Zwicky Transient Facility
  61. GRB 220823A: Fermi GBM detection
  62. Fermi-LAT gamma-ray observations of IceCube-220822A and detection of a new gamma-ray source, Fermi J1810.1+2154
  63. Fermi trigger No 682918137: Global MASTER-Net observations report
  64. GRB 220823A: Swift/BAT-GUANO detection of a short burst
  65. IceCube-220822A - IceCube observation of a high-energy neutrino candidate track-like event
  66. IceCube Alert 220822.85: Global MASTER-Net observations report
  67. GRB 220821A: Fermi GBM Final Real-time Localization
  68. Konus-Wind detection of GRB 220813A
  69. GRB 220813A: VLT optical observations and possible host galaxy
  70. GRB 220813A: Swift/UVOT Detection
  71. GRB 220810A: Further Swift-XRT observations
  72. GRB 220813A: Swift-XRT refined Analysis
  73. Swift GRB 220813A: Global MASTER-Net observations report
  74. GRB 220813A: Enhanced Swift-XRT position
  75. GRB 220813A: Swift detection of a burst with an optical counterpart
  76. GRB 220810A: Swift-XRT observations
  77. GRB 220719A: Detection by VZLUSAT-2
  78. Fermi trigger No 681998863: Global MASTER-Net observations report
  79. GRB 220810A: Swift ToO observations
  80. GRB 220810A: MeerLICHT detection of two afterglow candidates
  81. Fermi GBM trigger 681998863/220812505 is not a GRB
  82. Fermi trigger No 681890304: Global MASTER-Net observations report
  83. Fermi GBM trigger 681890304/220811249 is not a GRB
  84. Fermi GRB 220810A: Global MASTER-Net observations report
  85. GRB 220810A: Fermi GBM Final Real-time Localization
  86. GRB 220627A: MeerKAT radio observations
  87. GRB 220806A: Swift-BAT refined analysis
  88. Fermi trigger No 681719116: Global MASTER-Net observations report
  89. Fermi GBM trigger 681719116/220809267 is not a GRB
  90. Fermi trigger No 681633544: Global MASTER-Net observations report
  91. IceCube Astrotrack Bronze 136918_45252263.amon is likely background
  92. Fermi GBM trigger 681633544/220808277 is not a GRB
  93. IceCube Alert 220808.33: Global MASTER-Net observations report
  94. Fermi GBM trigger 681547990 / 220807287 is not a GRB
  95. GRB 220806A: Swift detection of a burst
  96. Swift GRB220806.76: Global MASTER-Net observations report
  97. GRB 220804A: Fermi GBM Final Localization
  98. Fermi trigger No 681271717: Global MASTER-Net observations report
  99. GRB 220803A: AstroSat CZTI detection
  100. Fermi trigger No 681212354: Global MASTER-Net observations report

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