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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. Fermi trigger No 683202084: Global MASTER-Net observations report
  2. Fermi trigger No 683183601: Global MASTER-Net observations report
  3. Fermi trigger No 683152759: Global MASTER-Net observations report
  4. GRB 220826A: Swift-XRT refined Analysis
  5. GRB 220825A: Fermi GBM observation
  6. GRB 220826A: Lesedi optical afterglow detection
  7. GRB 220826A: Swift/UVOT Detection
  8. GRB 220826A: iTelescope optical afterglow observations
  9. Swift GRB 220826A: Global MASTER-Net observations report
  10. GRB 220826A: Enhanced Swift-XRT position
  11. GRB 220826A: Swift detection of a burst with an optical counterpart
  12. GRB 220825A: Swift/BAT-GUANO detection
  13. GRB 220825A: Fermi GBM Final Localization
  14. IceCube-220822A: Upper limits from a search for additional neutrino events in IceCube
  15. IceCube-220822A: One Candidate Counterpart from the Zwicky Transient Facility
  16. GRB 220823A: Fermi GBM detection
  17. Fermi-LAT gamma-ray observations of IceCube-220822A and detection of a new gamma-ray source, Fermi J1810.1+2154
  18. Fermi trigger No 682918137: Global MASTER-Net observations report
  19. GRB 220823A: Swift/BAT-GUANO detection of a short burst
  20. IceCube-220822A - IceCube observation of a high-energy neutrino candidate track-like event
  21. IceCube Alert 220822.85: Global MASTER-Net observations report
  22. GRB 220821A: Fermi GBM Final Real-time Localization
  23. Konus-Wind detection of GRB 220813A
  24. GRB 220813A: VLT optical observations and possible host galaxy
  25. GRB 220813A: Swift/UVOT Detection
  26. GRB 220810A: Further Swift-XRT observations
  27. GRB 220813A: Swift-XRT refined Analysis
  28. Swift GRB 220813A: Global MASTER-Net observations report
  29. GRB 220813A: Enhanced Swift-XRT position
  30. GRB 220813A: Swift detection of a burst with an optical counterpart
  31. GRB 220810A: Swift-XRT observations
  32. GRB 220719A: Detection by VZLUSAT-2
  33. Fermi trigger No 681998863: Global MASTER-Net observations report
  34. GRB 220810A: Swift ToO observations
  35. GRB 220810A: MeerLICHT detection of two afterglow candidates
  36. Fermi GBM trigger 681998863/220812505 is not a GRB
  37. Fermi trigger No 681890304: Global MASTER-Net observations report
  38. Fermi GBM trigger 681890304/220811249 is not a GRB
  39. Fermi GRB 220810A: Global MASTER-Net observations report
  40. GRB 220810A: Fermi GBM Final Real-time Localization
  41. GRB 220627A: MeerKAT radio observations
  42. GRB 220806A: Swift-BAT refined analysis
  43. Fermi trigger No 681719116: Global MASTER-Net observations report
  44. Fermi GBM trigger 681719116/220809267 is not a GRB
  45. Fermi trigger No 681633544: Global MASTER-Net observations report
  46. IceCube Astrotrack Bronze 136918_45252263.amon is likely background
  47. Fermi GBM trigger 681633544/220808277 is not a GRB
  48. IceCube Alert 220808.33: Global MASTER-Net observations report
  49. Fermi GBM trigger 681547990 / 220807287 is not a GRB
  50. GRB 220806A: Swift detection of a burst
  51. Swift GRB220806.76: Global MASTER-Net observations report
  52. GRB 220804A: Fermi GBM Final Localization
  53. Fermi trigger No 681271717: Global MASTER-Net observations report
  54. GRB 220803A: AstroSat CZTI detection
  55. Fermi trigger No 681212354: Global MASTER-Net observations report
  56. Konus-Wind detection of GRB 220730A (short)
  57. GRB 220730A: Swift-BAT refined analysis
  58. GRB 220730A: Fermi GBM detection
  59. GRB 220730A: Swift-XRT afterglow detection
  60. GRB 220730A: Swift/UVOT Upper Limits
  61. GRB 220730A: Swift-XRT observations
  62. GRB 220729A: AstroSat CZTI detection
  63. Swift GRB 220730A: Global MASTER-Net observations report
  64. GRB 220730A: Swift detection of a short hard burst
  65. Fermi trigger No 680782656: Global MASTER-Net observations report
  66. Fermi GRB 220728A: Global MASTER-Net observations report
  67. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220728A
  68. GRB 220728A: Fermi GBM Final Real-time Localization
  69. GRB 220726A: Fermi GBM Final Real-time Localization
  70. Fermi trigger No 680421061: Global MASTER-Net observations report
  71. Fermi GRB 220724A: Global MASTER-Net observations report
  72. GRB 220724A: Fermi GBM Final Real-time Localization
  73. GRB 220715B: VIRT Optical Upper Limit
  74. Fermi GRB 220721A: Global MASTER-Net observations report
  75. GRB 220721A: Fermi GBM Final Real-time Localization
  76. Introducing new GCN Kafka broker and web site for transient alerts, https://gcn.nasa.gov
  77. Retraction: Fermi GBM trigger 679932336.585264/220719587 is not a GRB
  78. GRB 220715A: CALET Gamma-Ray Burst Monitor detection
  79. GRB 220711B: CALET Gamma-Ray Burst Monitor detection
  80. GRB 220719A: Fermi GBM Final Real-time Localization
  81. GRB 220715B: Swift-BAT refined analysis
  82. GRB220714B: UVOT detections
  83. GRB 220715B: Fermi GBM detection
  84. GRB 220715B: Swift-XRT refined Analysis
  85. GRB 220715B: Swift/UVOT Upper Limits
  86. GRB 220715B: Enhanced Swift-XRT position
  87. GRB 220715B: BOOTES-network optical upper limits
  88. Swift GRB 220715B: Global MASTER-Net observations report
  89. GRB 220715B: Prompt enhanced Swift-XRT position
  90. GRB 220715B: Swift detection of a burst
  91. GRB 220715B: Fermi GBM Final Real-time Localization
  92. GRB 220714B: Swift-BAT refined analysis
  93. GRB 220714B: Fermi GBM observation
  94. GRB 220715A: AGILE/MCAL detection
  95. GRB 220714B: LCO Optical Observations
  96. GRB 220715A: Fermi GBM Final Real-time Localization
  97. GRB 220714B: Swift-XRT refined Analysis
  98. Swift/BAT Trigger 1116172 (=GRB 220714A) is not a real astrophysical event
  99. GRB 220714B: UVOT afterglow discovery
  100. GRB 220714B: Enhanced Swift-XRT position

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