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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 230414B: Global MASTER-Net observations report
  2. GRB 230414B: Prompt enhanced Swift-XRT position
  3. GRB 230414B: Swift detection of a burst
  4. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  5. GRB 230414A: Fermi GBM Final Real-time Localization
  6. GRB 230328B: redshift lower limit estimating
  7. GRB 230409B: Mondy optical upper limit
  8. GRB 230409B: OHP/T193 optical upper limit
  9. GRB 230410B: VZLUSAT-2 detection
  10. GRB 230409D: VZLUSAT-2 detection
  11. GRB 230410B: AGILE detection of a burst
  12. GRB 230410A: Fermi GBM Final Real-time Localization
  13. Fermi GRB 230409C: Global MASTER-Net observations report
  14. Fermi GRB 230409A: Global MASTER-Net observations report
  15. GRB 230409C: Fermi GBM Final Real-time Localization
  16. GRB 230409B: Swift-XRT refined Analysis
  17. GRB 230409B: Swift-BAT refined analysis
  18. Fermi trigger No 702745263: Global MASTER-Net observations report
  19. Swift GRB 230409B: Global MASTER-Net observations report
  20. GRB 230409B: Swift/UVOT Detection
  21. GRB 230409B: Enhanced Swift-XRT position
  22. MAXI GRB230408.82: Global MASTER-Net observations report
  23. GRB 230409B: Swift detection of a burst
  24. GRB 230409A: Fermi GBM Final Real-time Localization
  25. GRB 230405B: VZLUSAT-2 detection
  26. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  27. Fermi-LAT gamma-ray observations of IceCube-230405A
  28. Konus-Wind detection of GRB 230405B
  29. GRB 230405B: AGILE detection
  30. GRB 230405B: Swift-XRT refined Analysis
  31. GRB 230405B: Fermi GBM Observation
  32. GRB 230405B: MeerLICHT upper limits
  33. IceCube Alert 230405.56: Global MASTER-Net observations report
  34. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  35. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  36. GRB 230307A: good match with kilonova models
  37. GRB 230307A: short mininum variability timescale compatible with a merger origin
  38. GRB 230405B: Swift/UVOT Upper Limits
  39. GRB 230405B: AstroSat CZTI detection
  40. GRB 230405B: Enhanced Swift-XRT position
  41. Swift GRB 230405B: Global MASTER-Net observations report
  42. GRB 230405B: Prompt enhanced Swift-XRT position
  43. GRB 230405B: Swift detection of a burst
  44. GRB 230405B: Fermi GBM Final Real-time Localization
  45. GRB 230307A: JWST observations consistent with the presence of a kilonova
  46. Fermi GRB 230405A: Global MASTER-Net observations report
  47. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  48. GRB 230405A: Fermi GBM Final Real-time Localization
  49. GRB 230404A: AstroSat CZTI detection
  50. GRB 230404A: Fermi GBM Final Real-time Localization
  51. GRB 230402A: CALET Gamma-Ray Burst Monitor detection
  52. GRB 230402A: AstroSat CZTI detection
  53. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  54. IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
  55. GRB 230328B: Multa observatory optical afterglow observation
  56. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  57. GRB 230228A: detection by GTC of the potential host galaxy
  58. GRB 230328B: Swift/UVOT Detection
  59. GRB 230402A: AGILE detection
  60. Fermi GRB 230402A: Global MASTER-Net observations report
  61. GRB 230402A: Fermi GBM Final Real-time Localization
  62. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  63. GRB 230307A: Bad Time Intervals for Fermi GBM data
  64. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  65. GRB 230328B: CAHA 2.2m/CAFOS detection
  66. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 230328B: 3.6m DOT multiband optical observation
  68. Fermi trigger No 701883729: Global MASTER-Net observations report
  69. GRB 230330B: Fermi GBM Final Localization
  70. Konus-Wind detection of GRB 230328B
  71. GRB 230328B: GRBAlpha detection
  72. GRB 230330A: Fermi GBM Final Real-time Localization
  73. GRB 230328B: Swift-BAT refined analysis
  74. GRB 230328B: Nanshan/NEXT 2nd optical observation
  75. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  76. GRB 230328B: Liverpool Telescope afterglow detection
  77. GRB 230328B: OHP/T120 optical observations
  78. GRB 230328B: GIT optical follow-up
  79. GRB 230328B: OASDG optical observations
  80. GRB 230328B: Nanshan/NEXT optical upper limit
  81. GRB 230328B: Swift-XRT refined Analysis
  82. GRB 230328B: AstroSat CZTI detection
  83. GRB 230328B: Fermi GBM observation
  84. GRB 230328B: Mondy, AbAO and Kitab optical observations
  85. GRB 230328B: Enhanced Swift-XRT position
  86. GRB 230328B: Mondy optical afterglow confirmation
  87. GRB 230328B: Swift detection of a burst with an optical afterglow
  88. GRB 230328B: Fermi GBM Final Real-time Localization
  89. Fermi GRB 230328A: Global MASTER-Net observations report
  90. GRB 230328A: Fermi GBM Final Real-time Localization
  91. GRB 230325A: Swift-BAT refined analysis
  92. GRB 230325A: Swift/UVOT Upper Limits
  93. GRB 230325A: X-shooter optical afterglow and redshift
  94. GRB 230325A: Swift-XRT refined Analysis
  95. GRB 230322B: Swift-BAT refined analysis
  96. GRB 230325A: Enhanced Swift-XRT position
  97. GRB 230325A: Prompt enhanced Swift-XRT position
  98. GRB 230325A: Swift detection of a burst
  99. GRB 230320B: Fermi GBM Observation
  100. Fermi trigger No 701313046: Global MASTER-Net observations report

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