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

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