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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. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  2. GRB 240213A: GRBAlpha detection
  3. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  4. GRB240218A: VLT/X-shooter upper limits
  5. GRB 240218A: Swift detection of a burst
  6. Swift GRB240218.08: Global MASTER-Net observations report
  7. GRB 240215C: Fermi GBM Final Real-time Localization
  8. GRB 240215B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  9. Fermi GRB 240216A: Global MASTER-Net observations report
  10. Swift Triggers 12156887-1215690 are not astrophysical events.
  11. GRB 240216A: Fermi GBM Final Real-time Localization
  12. Fermi trigger No 729719508: Global MASTER-Net observations report
  13. GRB 240215A: Tiled Swift observations
  14. GRB 240215A: Swift/BAT-GUANO localization of a burst
  15. Fermi trigger No 729703985: Global MASTER-Net observations report
  16. Fermi trigger No 729650855: Global MASTER-Net observations report
  17. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  18. GRB 240209A: Fermi GBM observation
  19. GRB 240213A: Glowbug gamma-ray detection
  20. The AGILE satellite ceased operations and re-entered today into the atmosphere
  21. The AGILE satellite ceased operations and re-entered today into the atmosphere
  22. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  23. GRB 240209A: Wendelstein Optical Observations
  24. GRB 240128A: Further Swift-XRT observations
  25. GRB 240214A: Tiled Swift observations
  26. GRB 240214A/1H 0451-560: MAXI/GSC detection
  27. GRB 240213A: BALROG localization (Fermi Trigger / GRB 240213841)
  28. Fermi GRB 240213A: Global MASTER-Net observations report
  29. GRB 240213A: Fermi GBM Final Real-time Localization
  30. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  31. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  32. GRB 240209A: GOTO optical counterpart candidate
  33. Konus-Wind detection of GRB 240204A
  34. Konus-Wind detection of GRB 240205A (short)
  35. GRB 240209A: Fermi GBM Final Localization
  36. Fermi trigger No 729152364: Global MASTER-Net observations report
  37. IPN triangulation of GRB 240205A (short)
  38. Fermi-LAT gamma-ray observations of IceCube-240204A
  39. GRB 240205B: PRIME near infrared detection
  40. GRB 240205A (short): Glowbug gamma-ray detection
  41. Swift Trigger 1213872 is not an astrophysical event
  42. GRB240204A: Swift/UVOT Upper Limits
  43. GRB 240205B: AstroSat CZTI detection
  44. Fermi trigger No 729012023: Global MASTER-Net observations report
  45. GRB 240205B: Swift-BAT refined analysis
  46. Konus-Wind detection of GRB 240205B (long / very soft)
  47. GRB 240207A: Fermi GBM Final Real-time Localization
  48. Konus-Wind detection of GRB 240125A
  49. GRB 240205B: VLT/X-shooter redshift
  50. GRB 240205B: CALET Gamma-Ray Burst Monitor detection
  51. GRB 240205B: BOOTES-6 optical afterglow follow-up
  52. GRB 240205B: ATCA detection of radio counterpart
  53. GRB 240205B: REM detection of the optical/NIR afterglow
  54. GRB 240205B: Fermi GBM Observation
  55. GRB 240204A: AstroSat CZTI detection
  56. GRB 240204A: Mondy optical afterglow observations
  57. GRB 240204A : OHP/T193/T120 optical afterglow fading detection
  58. GRB 240205B: GECAM detection of a long burst
  59. GRB 240204A: Swift-BAT refined analysis
  60. GRB 240205B: Skynet Optical Afterglow Observations
  61. GRB 240205B: BOOTES-7 optical afterglow follow-up
  62. Fermi trigger No 728749569: Global MASTER-Net observations report
  63. GRB 240205B: MASTER OT J232550.14-550704.6 counterpart detection
  64. GRB 240205B: Swift detection of a burst
  65. GRB 240205B: Fermi GBM Final Real-time Localization
  66. Swift GRB240205.93: Global MASTER-Net observations report
  67. GRB 240204A: Fermi GBM Observation
  68. GRB 240205A: Fermi GBM Final Real-time Localization
  69. GRB 240204a: Liverpool Telescope optical afterglow detection
  70. GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
  71. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  72. Fermi Gamma-ray Burst Monitor trigger 728740048/240204491 is not a GRB
  73. Fermi trigger No 728796365: Global MASTER-Net observations report
  74. GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
  75. GRB 240204A: Montarrenti Observatory optical observations
  76. GRB 240204A: Enhanced Swift-XRT position
  77. GRB 240204A: Mondy optical afterglow candidate
  78. Fermi Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
  79. Fermi GRB 240204A: Global MASTER-Net observations report
  80. Fermi trigger No 728706420: Global MASTER-Net observations report
  81. GRB 240204A: Swift detection of a burst
  82. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  83. GRB 240204A: Fermi GBM Final Real-time Localization
  84. IceCube Alert 240204.38: Global MASTER-Net observations report
  85. Swift Trigger 1212791 is not an astrophysical event.
  86. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  87. GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
  88. Konus-Wind detection of GRB 240124B
  89. Konus-Wind detection of GRB 240123C
  90. IPN triangulation of GRB 240124B
  91. GRB 240201A: AstroSat CZTI detection
  92. GRB 240129A: Fermi GBM Observation
  93. IPN triangulation of GRB 240125B (short)
  94. GRB 240129A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  95. IPN triangulation of GRB 240125A (short)
  96. GRB 240128A: Glowbug gamma-ray detection
  97. GRB 240128A: Swift-XRT observations
  98. GRB 240128A: GRBAlpha detection
  99. GRB 240128A: Tiled Swift observations
  100. GRB 240128A: CALET Gamma-Ray Burst Monitor detection

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