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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 240215A: Tiled Swift observations
  2. GRB 240215A: Swift/BAT-GUANO localization of a burst
  3. Fermi trigger No 729703985: Global MASTER-Net observations report
  4. Fermi trigger No 729650855: Global MASTER-Net observations report
  5. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  6. GRB 240209A: Fermi GBM observation
  7. GRB 240213A: Glowbug gamma-ray detection
  8. The AGILE satellite ceased operations and re-entered today into the atmosphere
  9. The AGILE satellite ceased operations and re-entered today into the atmosphere
  10. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  11. GRB 240209A: Wendelstein Optical Observations
  12. GRB 240128A: Further Swift-XRT observations
  13. GRB 240214A: Tiled Swift observations
  14. GRB 240214A/1H 0451-560: MAXI/GSC detection
  15. GRB 240213A: BALROG localization (Fermi Trigger / GRB 240213841)
  16. Fermi GRB 240213A: Global MASTER-Net observations report
  17. GRB 240213A: Fermi GBM Final Real-time Localization
  18. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  19. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  20. GRB 240209A: GOTO optical counterpart candidate
  21. Konus-Wind detection of GRB 240204A
  22. Konus-Wind detection of GRB 240205A (short)
  23. GRB 240209A: Fermi GBM Final Localization
  24. Fermi trigger No 729152364: Global MASTER-Net observations report
  25. IPN triangulation of GRB 240205A (short)
  26. Fermi-LAT gamma-ray observations of IceCube-240204A
  27. GRB 240205B: PRIME near infrared detection
  28. GRB 240205A (short): Glowbug gamma-ray detection
  29. Swift Trigger 1213872 is not an astrophysical event
  30. GRB240204A: Swift/UVOT Upper Limits
  31. GRB 240205B: AstroSat CZTI detection
  32. Fermi trigger No 729012023: Global MASTER-Net observations report
  33. GRB 240205B: Swift-BAT refined analysis
  34. Konus-Wind detection of GRB 240205B (long / very soft)
  35. GRB 240207A: Fermi GBM Final Real-time Localization
  36. Konus-Wind detection of GRB 240125A
  37. GRB 240205B: VLT/X-shooter redshift
  38. GRB 240205B: CALET Gamma-Ray Burst Monitor detection
  39. GRB 240205B: BOOTES-6 optical afterglow follow-up
  40. GRB 240205B: ATCA detection of radio counterpart
  41. GRB 240205B: REM detection of the optical/NIR afterglow
  42. GRB 240205B: Fermi GBM Observation
  43. GRB 240204A: AstroSat CZTI detection
  44. GRB 240204A: Mondy optical afterglow observations
  45. GRB 240204A : OHP/T193/T120 optical afterglow fading detection
  46. GRB 240205B: GECAM detection of a long burst
  47. GRB 240204A: Swift-BAT refined analysis
  48. GRB 240205B: Skynet Optical Afterglow Observations
  49. GRB 240205B: BOOTES-7 optical afterglow follow-up
  50. Fermi trigger No 728749569: Global MASTER-Net observations report
  51. GRB 240205B: MASTER OT J232550.14-550704.6 counterpart detection
  52. GRB 240205B: Swift detection of a burst
  53. GRB 240205B: Fermi GBM Final Real-time Localization
  54. Swift GRB240205.93: Global MASTER-Net observations report
  55. GRB 240204A: Fermi GBM Observation
  56. GRB 240205A: Fermi GBM Final Real-time Localization
  57. GRB 240204a: Liverpool Telescope optical afterglow detection
  58. GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
  59. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  60. Fermi Gamma-ray Burst Monitor trigger 728740048/240204491 is not a GRB
  61. Fermi trigger No 728796365: Global MASTER-Net observations report
  62. GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
  63. GRB 240204A: Montarrenti Observatory optical observations
  64. GRB 240204A: Enhanced Swift-XRT position
  65. GRB 240204A: Mondy optical afterglow candidate
  66. Fermi Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
  67. Fermi GRB 240204A: Global MASTER-Net observations report
  68. Fermi trigger No 728706420: Global MASTER-Net observations report
  69. GRB 240204A: Swift detection of a burst
  70. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 240204A: Fermi GBM Final Real-time Localization
  72. IceCube Alert 240204.38: Global MASTER-Net observations report
  73. Swift Trigger 1212791 is not an astrophysical event.
  74. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  75. GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
  76. Konus-Wind detection of GRB 240124B
  77. Konus-Wind detection of GRB 240123C
  78. IPN triangulation of GRB 240124B
  79. GRB 240201A: AstroSat CZTI detection
  80. GRB 240129A: Fermi GBM Observation
  81. IPN triangulation of GRB 240125B (short)
  82. GRB 240129A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  83. IPN triangulation of GRB 240125A (short)
  84. GRB 240128A: Glowbug gamma-ray detection
  85. GRB 240128A: Swift-XRT observations
  86. GRB 240128A: GRBAlpha detection
  87. GRB 240128A: Tiled Swift observations
  88. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  89. GRB 240128A: MAXI/GSC detection
  90. GRB 240125A: GRBAlpha detection
  91. Fermi GRB 240127A: Global MASTER-Net observations report
  92. GRB 240123C: GRBAlpha detection
  93. GRB 240122A: ATCA detection of radio counterpart
  94. GRB 240127A: Fermi GBM Final Real-time Localization
  95. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  96. GRB 240125A: CALET Gamma-Ray Burst Monitor detection
  97. Swift Trigger 1211211 and 1211212 are not astrophysical
  98. GRB 240125A: AstroSat CZTI detection of a short burst
  99. GRB 240124B: AstroSat CZTI detection
  100. GRB 240123C: AstroSat CZTI detection

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