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

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