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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 240215B: Fermi GBM Observation
  2. GRB 240218A: LBT H-band detection
  3. GRB 240218A: Swift-BAT refined analysis
  4. Fermi GRB 240220A: Global MASTER-Net observations report
  5. GRB 240220A: Fermi GBM Final Real-time Localization
  6. Konus-Wind detection of GRB 240218A
  7. GRB 240218A: Swift-XRT refined Analysis
  8. GRB 240218A: VLT/X-shooter redshift of z = 6.782
  9. GRB 240218A: Fermi GBM Detection
  10. GRB 240215A: Fermi GBM Observation
  11. GRB 240216A: GRBAlpha detection
  12. GRB 240215B: GRBAlpha detection
  13. IPN triangulation of GRB 240209A
  14. Fermi trigger No 729914426: Global MASTER-Net observations report
  15. GRB 240218A: VLT/FORS2 z-band detection
  16. GRB 240218A: Enhanced Swift-XRT position
  17. GRB 240218A: REM detection of a NIR afterglow candidate
  18. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  19. GRB 240213A: GRBAlpha detection
  20. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  21. GRB240218A: VLT/X-shooter upper limits
  22. GRB 240218A: Swift detection of a burst
  23. Swift GRB240218.08: Global MASTER-Net observations report
  24. GRB 240215C: Fermi GBM Final Real-time Localization
  25. GRB 240215B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  26. Fermi GRB 240216A: Global MASTER-Net observations report
  27. Swift Triggers 12156887-1215690 are not astrophysical events.
  28. GRB 240216A: Fermi GBM Final Real-time Localization
  29. Fermi trigger No 729719508: Global MASTER-Net observations report
  30. GRB 240215A: Tiled Swift observations
  31. GRB 240215A: Swift/BAT-GUANO localization of a burst
  32. Fermi trigger No 729703985: Global MASTER-Net observations report
  33. Fermi trigger No 729650855: Global MASTER-Net observations report
  34. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  35. GRB 240209A: Fermi GBM observation
  36. GRB 240213A: Glowbug gamma-ray detection
  37. The AGILE satellite ceased operations and re-entered today into the atmosphere
  38. The AGILE satellite ceased operations and re-entered today into the atmosphere
  39. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  40. GRB 240209A: Wendelstein Optical Observations
  41. GRB 240128A: Further Swift-XRT observations
  42. GRB 240214A: Tiled Swift observations
  43. GRB 240214A/1H 0451-560: MAXI/GSC detection
  44. GRB 240213A: BALROG localization (Fermi Trigger / GRB 240213841)
  45. Fermi GRB 240213A: Global MASTER-Net observations report
  46. GRB 240213A: Fermi GBM Final Real-time Localization
  47. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  48. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  49. GRB 240209A: GOTO optical counterpart candidate
  50. Konus-Wind detection of GRB 240204A
  51. Konus-Wind detection of GRB 240205A (short)
  52. GRB 240209A: Fermi GBM Final Localization
  53. Fermi trigger No 729152364: Global MASTER-Net observations report
  54. IPN triangulation of GRB 240205A (short)
  55. Fermi-LAT gamma-ray observations of IceCube-240204A
  56. GRB 240205B: PRIME near infrared detection
  57. GRB 240205A (short): Glowbug gamma-ray detection
  58. Swift Trigger 1213872 is not an astrophysical event
  59. GRB240204A: Swift/UVOT Upper Limits
  60. GRB 240205B: AstroSat CZTI detection
  61. Fermi trigger No 729012023: Global MASTER-Net observations report
  62. GRB 240205B: Swift-BAT refined analysis
  63. Konus-Wind detection of GRB 240205B (long / very soft)
  64. GRB 240207A: Fermi GBM Final Real-time Localization
  65. Konus-Wind detection of GRB 240125A
  66. GRB 240205B: VLT/X-shooter redshift
  67. GRB 240205B: CALET Gamma-Ray Burst Monitor detection
  68. GRB 240205B: BOOTES-6 optical afterglow follow-up
  69. GRB 240205B: ATCA detection of radio counterpart
  70. GRB 240205B: REM detection of the optical/NIR afterglow
  71. GRB 240205B: Fermi GBM Observation
  72. GRB 240204A: AstroSat CZTI detection
  73. GRB 240204A: Mondy optical afterglow observations
  74. GRB 240204A : OHP/T193/T120 optical afterglow fading detection
  75. GRB 240205B: GECAM detection of a long burst
  76. GRB 240204A: Swift-BAT refined analysis
  77. GRB 240205B: Skynet Optical Afterglow Observations
  78. GRB 240205B: BOOTES-7 optical afterglow follow-up
  79. Fermi trigger No 728749569: Global MASTER-Net observations report
  80. GRB 240205B: MASTER OT J232550.14-550704.6 counterpart detection
  81. GRB 240205B: Swift detection of a burst
  82. GRB 240205B: Fermi GBM Final Real-time Localization
  83. Swift GRB240205.93: Global MASTER-Net observations report
  84. GRB 240204A: Fermi GBM Observation
  85. GRB 240205A: Fermi GBM Final Real-time Localization
  86. GRB 240204a: Liverpool Telescope optical afterglow detection
  87. GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
  88. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  89. Fermi Gamma-ray Burst Monitor trigger 728740048/240204491 is not a GRB
  90. Fermi trigger No 728796365: Global MASTER-Net observations report
  91. GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
  92. GRB 240204A: Montarrenti Observatory optical observations
  93. GRB 240204A: Enhanced Swift-XRT position
  94. GRB 240204A: Mondy optical afterglow candidate
  95. Fermi Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
  96. Fermi GRB 240204A: Global MASTER-Net observations report
  97. Fermi trigger No 728706420: Global MASTER-Net observations report
  98. GRB 240204A: Swift detection of a burst
  99. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  100. GRB 240204A: Fermi GBM Final Real-time Localization

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