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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 220826A: Swift/UVOT Detection
  2. GRB 220826A: iTelescope optical afterglow observations
  3. Swift GRB 220826A: Global MASTER-Net observations report
  4. GRB 220826A: Enhanced Swift-XRT position
  5. GRB 220826A: Swift detection of a burst with an optical counterpart
  6. GRB 220825A: Swift/BAT-GUANO detection
  7. GRB 220825A: Fermi GBM Final Localization
  8. IceCube-220822A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-220822A: One Candidate Counterpart from the Zwicky Transient Facility
  10. GRB 220823A: Fermi GBM detection
  11. Fermi-LAT gamma-ray observations of IceCube-220822A and detection of a new gamma-ray source, Fermi J1810.1+2154
  12. Fermi trigger No 682918137: Global MASTER-Net observations report
  13. GRB 220823A: Swift/BAT-GUANO detection of a short burst
  14. IceCube-220822A - IceCube observation of a high-energy neutrino candidate track-like event
  15. IceCube Alert 220822.85: Global MASTER-Net observations report
  16. GRB 220821A: Fermi GBM Final Real-time Localization
  17. Konus-Wind detection of GRB 220813A
  18. GRB 220813A: VLT optical observations and possible host galaxy
  19. GRB 220813A: Swift/UVOT Detection
  20. GRB 220810A: Further Swift-XRT observations
  21. GRB 220813A: Swift-XRT refined Analysis
  22. Swift GRB 220813A: Global MASTER-Net observations report
  23. GRB 220813A: Enhanced Swift-XRT position
  24. GRB 220813A: Swift detection of a burst with an optical counterpart
  25. GRB 220810A: Swift-XRT observations
  26. GRB 220719A: Detection by VZLUSAT-2
  27. Fermi trigger No 681998863: Global MASTER-Net observations report
  28. GRB 220810A: Swift ToO observations
  29. GRB 220810A: MeerLICHT detection of two afterglow candidates
  30. Fermi GBM trigger 681998863/220812505 is not a GRB
  31. Fermi trigger No 681890304: Global MASTER-Net observations report
  32. Fermi GBM trigger 681890304/220811249 is not a GRB
  33. Fermi GRB 220810A: Global MASTER-Net observations report
  34. GRB 220810A: Fermi GBM Final Real-time Localization
  35. GRB 220627A: MeerKAT radio observations
  36. GRB 220806A: Swift-BAT refined analysis
  37. Fermi trigger No 681719116: Global MASTER-Net observations report
  38. Fermi GBM trigger 681719116/220809267 is not a GRB
  39. Fermi trigger No 681633544: Global MASTER-Net observations report
  40. IceCube Astrotrack Bronze 136918_45252263.amon is likely background
  41. Fermi GBM trigger 681633544/220808277 is not a GRB
  42. IceCube Alert 220808.33: Global MASTER-Net observations report
  43. Fermi GBM trigger 681547990 / 220807287 is not a GRB
  44. GRB 220806A: Swift detection of a burst
  45. Swift GRB220806.76: Global MASTER-Net observations report
  46. GRB 220804A: Fermi GBM Final Localization
  47. Fermi trigger No 681271717: Global MASTER-Net observations report
  48. GRB 220803A: AstroSat CZTI detection
  49. Fermi trigger No 681212354: Global MASTER-Net observations report
  50. Konus-Wind detection of GRB 220730A (short)
  51. GRB 220730A: Swift-BAT refined analysis
  52. GRB 220730A: Fermi GBM detection
  53. GRB 220730A: Swift-XRT afterglow detection
  54. GRB 220730A: Swift/UVOT Upper Limits
  55. GRB 220730A: Swift-XRT observations
  56. GRB 220729A: AstroSat CZTI detection
  57. Swift GRB 220730A: Global MASTER-Net observations report
  58. GRB 220730A: Swift detection of a short hard burst
  59. Fermi trigger No 680782656: Global MASTER-Net observations report
  60. Fermi GRB 220728A: Global MASTER-Net observations report
  61. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-220728A
  62. GRB 220728A: Fermi GBM Final Real-time Localization
  63. GRB 220726A: Fermi GBM Final Real-time Localization
  64. Fermi trigger No 680421061: Global MASTER-Net observations report
  65. Fermi GRB 220724A: Global MASTER-Net observations report
  66. GRB 220724A: Fermi GBM Final Real-time Localization
  67. GRB 220715B: VIRT Optical Upper Limit
  68. Fermi GRB 220721A: Global MASTER-Net observations report
  69. GRB 220721A: Fermi GBM Final Real-time Localization
  70. Introducing new GCN Kafka broker and web site for transient alerts, https://gcn.nasa.gov
  71. Retraction: Fermi GBM trigger 679932336.585264/220719587 is not a GRB
  72. GRB 220715A: CALET Gamma-Ray Burst Monitor detection
  73. GRB 220711B: CALET Gamma-Ray Burst Monitor detection
  74. GRB 220719A: Fermi GBM Final Real-time Localization
  75. GRB 220715B: Swift-BAT refined analysis
  76. GRB220714B: UVOT detections
  77. GRB 220715B: Fermi GBM detection
  78. GRB 220715B: Swift-XRT refined Analysis
  79. GRB 220715B: Swift/UVOT Upper Limits
  80. GRB 220715B: Enhanced Swift-XRT position
  81. GRB 220715B: BOOTES-network optical upper limits
  82. Swift GRB 220715B: Global MASTER-Net observations report
  83. GRB 220715B: Prompt enhanced Swift-XRT position
  84. GRB 220715B: Swift detection of a burst
  85. GRB 220715B: Fermi GBM Final Real-time Localization
  86. GRB 220714B: Swift-BAT refined analysis
  87. GRB 220714B: Fermi GBM observation
  88. GRB 220715A: AGILE/MCAL detection
  89. GRB 220714B: LCO Optical Observations
  90. GRB 220715A: Fermi GBM Final Real-time Localization
  91. GRB 220714B: Swift-XRT refined Analysis
  92. Swift/BAT Trigger 1116172 (=GRB 220714A) is not a real astrophysical event
  93. GRB 220714B: UVOT afterglow discovery
  94. GRB 220714B: Enhanced Swift-XRT position
  95. GRB 220713A: Fermi GBM Final Localization
  96. GRB 220714B: Swift detection of a burst
  97. GRB 220714B: Fermi GBM Final Real-time Localization
  98. GRB 220714A: Possible Swift detection of a burst
  99. GRB 220710A: Swift/UVOT Upper Limits
  100. GRB 220711C: Fermi GBM Observation

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