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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 230409C: Fermi GBM Final Real-time Localization
  2. GRB 230409B: Swift-XRT refined Analysis
  3. GRB 230409B: Swift-BAT refined analysis
  4. Fermi trigger No 702745263: Global MASTER-Net observations report
  5. Swift GRB 230409B: Global MASTER-Net observations report
  6. GRB 230409B: Swift/UVOT Detection
  7. GRB 230409B: Enhanced Swift-XRT position
  8. MAXI GRB230408.82: Global MASTER-Net observations report
  9. GRB 230409B: Swift detection of a burst
  10. GRB 230409A: Fermi GBM Final Real-time Localization
  11. GRB 230405B: VZLUSAT-2 detection
  12. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  13. Fermi-LAT gamma-ray observations of IceCube-230405A
  14. Konus-Wind detection of GRB 230405B
  15. GRB 230405B: AGILE detection
  16. GRB 230405B: Swift-XRT refined Analysis
  17. GRB 230405B: Fermi GBM Observation
  18. GRB 230405B: MeerLICHT upper limits
  19. IceCube Alert 230405.56: Global MASTER-Net observations report
  20. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  21. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  22. GRB 230307A: good match with kilonova models
  23. GRB 230307A: short mininum variability timescale compatible with a merger origin
  24. GRB 230405B: Swift/UVOT Upper Limits
  25. GRB 230405B: AstroSat CZTI detection
  26. GRB 230405B: Enhanced Swift-XRT position
  27. Swift GRB 230405B: Global MASTER-Net observations report
  28. GRB 230405B: Prompt enhanced Swift-XRT position
  29. GRB 230405B: Swift detection of a burst
  30. GRB 230405B: Fermi GBM Final Real-time Localization
  31. GRB 230307A: JWST observations consistent with the presence of a kilonova
  32. Fermi GRB 230405A: Global MASTER-Net observations report
  33. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  34. GRB 230405A: Fermi GBM Final Real-time Localization
  35. GRB 230404A: AstroSat CZTI detection
  36. GRB 230404A: Fermi GBM Final Real-time Localization
  37. GRB 230402A: CALET Gamma-Ray Burst Monitor detection
  38. GRB 230402A: AstroSat CZTI detection
  39. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  40. IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 230328B: Multa observatory optical afterglow observation
  42. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  43. GRB 230228A: detection by GTC of the potential host galaxy
  44. GRB 230328B: Swift/UVOT Detection
  45. GRB 230402A: AGILE detection
  46. Fermi GRB 230402A: Global MASTER-Net observations report
  47. GRB 230402A: Fermi GBM Final Real-time Localization
  48. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  49. GRB 230307A: Bad Time Intervals for Fermi GBM data
  50. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  51. GRB 230328B: CAHA 2.2m/CAFOS detection
  52. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 230328B: 3.6m DOT multiband optical observation
  54. Fermi trigger No 701883729: Global MASTER-Net observations report
  55. GRB 230330B: Fermi GBM Final Localization
  56. Konus-Wind detection of GRB 230328B
  57. GRB 230328B: GRBAlpha detection
  58. GRB 230330A: Fermi GBM Final Real-time Localization
  59. GRB 230328B: Swift-BAT refined analysis
  60. GRB 230328B: Nanshan/NEXT 2nd optical observation
  61. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  62. GRB 230328B: Liverpool Telescope afterglow detection
  63. GRB 230328B: OHP/T120 optical observations
  64. GRB 230328B: GIT optical follow-up
  65. GRB 230328B: OASDG optical observations
  66. GRB 230328B: Nanshan/NEXT optical upper limit
  67. GRB 230328B: Swift-XRT refined Analysis
  68. GRB 230328B: AstroSat CZTI detection
  69. GRB 230328B: Fermi GBM observation
  70. GRB 230328B: Mondy, AbAO and Kitab optical observations
  71. GRB 230328B: Enhanced Swift-XRT position
  72. GRB 230328B: Mondy optical afterglow confirmation
  73. GRB 230328B: Swift detection of a burst with an optical afterglow
  74. GRB 230328B: Fermi GBM Final Real-time Localization
  75. Fermi GRB 230328A: Global MASTER-Net observations report
  76. GRB 230328A: Fermi GBM Final Real-time Localization
  77. GRB 230325A: Swift-BAT refined analysis
  78. GRB 230325A: Swift/UVOT Upper Limits
  79. GRB 230325A: X-shooter optical afterglow and redshift
  80. GRB 230325A: Swift-XRT refined Analysis
  81. GRB 230322B: Swift-BAT refined analysis
  82. GRB 230325A: Enhanced Swift-XRT position
  83. GRB 230325A: Prompt enhanced Swift-XRT position
  84. GRB 230325A: Swift detection of a burst
  85. GRB 230320B: Fermi GBM Observation
  86. Fermi trigger No 701313046: Global MASTER-Net observations report
  87. Fermi trigger No 701321709: Global MASTER-Net observations report
  88. GRB 230322B: Swift/UVOT Detection
  89. Konus-Wind detection of GRB 230309A
  90. Konus-Wind detection of GRB 230308A
  91. Konus-Wind detection of GRB 230304B
  92. GRB 230322B: Swift-XRT refined Analysis
  93. GRB 230322B: Enhanced Swift-XRT position
  94. Swift GRB 230322B: Global MASTER-Net observations report
  95. GRB 230322B: Swift detection of a burst with optical counterpart
  96. GRB 230322A: Fermi GBM Final Real-time Localization
  97. GRB 230320B: GRBAlpha detection
  98. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  100. Fermi trigger No 701071944: Global MASTER-Net observations report

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