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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 230409B: Swift/UVOT Detection
  2. GRB 230409B: Enhanced Swift-XRT position
  3. MAXI GRB230408.82: Global MASTER-Net observations report
  4. GRB 230409B: Swift detection of a burst
  5. GRB 230409A: Fermi GBM Final Real-time Localization
  6. GRB 230405B: VZLUSAT-2 detection
  7. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  8. Fermi-LAT gamma-ray observations of IceCube-230405A
  9. Konus-Wind detection of GRB 230405B
  10. GRB 230405B: AGILE detection
  11. GRB 230405B: Swift-XRT refined Analysis
  12. GRB 230405B: Fermi GBM Observation
  13. GRB 230405B: MeerLICHT upper limits
  14. IceCube Alert 230405.56: Global MASTER-Net observations report
  15. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  16. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  17. GRB 230307A: good match with kilonova models
  18. GRB 230307A: short mininum variability timescale compatible with a merger origin
  19. GRB 230405B: Swift/UVOT Upper Limits
  20. GRB 230405B: AstroSat CZTI detection
  21. GRB 230405B: Enhanced Swift-XRT position
  22. Swift GRB 230405B: Global MASTER-Net observations report
  23. GRB 230405B: Prompt enhanced Swift-XRT position
  24. GRB 230405B: Swift detection of a burst
  25. GRB 230405B: Fermi GBM Final Real-time Localization
  26. GRB 230307A: JWST observations consistent with the presence of a kilonova
  27. Fermi GRB 230405A: Global MASTER-Net observations report
  28. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  29. GRB 230405A: Fermi GBM Final Real-time Localization
  30. GRB 230404A: AstroSat CZTI detection
  31. GRB 230404A: Fermi GBM Final Real-time Localization
  32. GRB 230402A: CALET Gamma-Ray Burst Monitor detection
  33. GRB 230402A: AstroSat CZTI detection
  34. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  35. IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 230328B: Multa observatory optical afterglow observation
  37. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  38. GRB 230228A: detection by GTC of the potential host galaxy
  39. GRB 230328B: Swift/UVOT Detection
  40. GRB 230402A: AGILE detection
  41. Fermi GRB 230402A: Global MASTER-Net observations report
  42. GRB 230402A: Fermi GBM Final Real-time Localization
  43. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  44. GRB 230307A: Bad Time Intervals for Fermi GBM data
  45. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  46. GRB 230328B: CAHA 2.2m/CAFOS detection
  47. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 230328B: 3.6m DOT multiband optical observation
  49. Fermi trigger No 701883729: Global MASTER-Net observations report
  50. GRB 230330B: Fermi GBM Final Localization
  51. Konus-Wind detection of GRB 230328B
  52. GRB 230328B: GRBAlpha detection
  53. GRB 230330A: Fermi GBM Final Real-time Localization
  54. GRB 230328B: Swift-BAT refined analysis
  55. GRB 230328B: Nanshan/NEXT 2nd optical observation
  56. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  57. GRB 230328B: Liverpool Telescope afterglow detection
  58. GRB 230328B: OHP/T120 optical observations
  59. GRB 230328B: GIT optical follow-up
  60. GRB 230328B: OASDG optical observations
  61. GRB 230328B: Nanshan/NEXT optical upper limit
  62. GRB 230328B: Swift-XRT refined Analysis
  63. GRB 230328B: AstroSat CZTI detection
  64. GRB 230328B: Fermi GBM observation
  65. GRB 230328B: Mondy, AbAO and Kitab optical observations
  66. GRB 230328B: Enhanced Swift-XRT position
  67. GRB 230328B: Mondy optical afterglow confirmation
  68. GRB 230328B: Swift detection of a burst with an optical afterglow
  69. GRB 230328B: Fermi GBM Final Real-time Localization
  70. Fermi GRB 230328A: Global MASTER-Net observations report
  71. GRB 230328A: Fermi GBM Final Real-time Localization
  72. GRB 230325A: Swift-BAT refined analysis
  73. GRB 230325A: Swift/UVOT Upper Limits
  74. GRB 230325A: X-shooter optical afterglow and redshift
  75. GRB 230325A: Swift-XRT refined Analysis
  76. GRB 230322B: Swift-BAT refined analysis
  77. GRB 230325A: Enhanced Swift-XRT position
  78. GRB 230325A: Prompt enhanced Swift-XRT position
  79. GRB 230325A: Swift detection of a burst
  80. GRB 230320B: Fermi GBM Observation
  81. Fermi trigger No 701313046: Global MASTER-Net observations report
  82. Fermi trigger No 701321709: Global MASTER-Net observations report
  83. GRB 230322B: Swift/UVOT Detection
  84. Konus-Wind detection of GRB 230309A
  85. Konus-Wind detection of GRB 230308A
  86. Konus-Wind detection of GRB 230304B
  87. GRB 230322B: Swift-XRT refined Analysis
  88. GRB 230322B: Enhanced Swift-XRT position
  89. Swift GRB 230322B: Global MASTER-Net observations report
  90. GRB 230322B: Swift detection of a burst with optical counterpart
  91. GRB 230322A: Fermi GBM Final Real-time Localization
  92. GRB 230320B: GRBAlpha detection
  93. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  94. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  95. Fermi trigger No 701071944: Global MASTER-Net observations report
  96. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  97. Fermi GRB 230320A: Global MASTER-Net observations report
  98. Fermi GRB 230321A: Global MASTER-Net observations report
  99. Fermi trigger No 701058254: Global MASTER-Net observations report
  100. SGR 1806-20: Correction to GCN 33494

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