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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. Fermi trigger No 728749569: Global MASTER-Net observations report
  2. GRB 240205B: MASTER OT J232550.14-550704.6 counterpart detection
  3. GRB 240205B: Swift detection of a burst
  4. GRB 240205B: Fermi GBM Final Real-time Localization
  5. Swift GRB240205.93: Global MASTER-Net observations report
  6. GRB 240204A: Fermi GBM Observation
  7. GRB 240205A: Fermi GBM Final Real-time Localization
  8. GRB 240204a: Liverpool Telescope optical afterglow detection
  9. GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
  10. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  11. Fermi Gamma-ray Burst Monitor trigger 728740048/240204491 is not a GRB
  12. Fermi trigger No 728796365: Global MASTER-Net observations report
  13. GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
  14. GRB 240204A: Montarrenti Observatory optical observations
  15. GRB 240204A: Enhanced Swift-XRT position
  16. GRB 240204A: Mondy optical afterglow candidate
  17. Fermi Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
  18. Fermi GRB 240204A: Global MASTER-Net observations report
  19. Fermi trigger No 728706420: Global MASTER-Net observations report
  20. GRB 240204A: Swift detection of a burst
  21. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 240204A: Fermi GBM Final Real-time Localization
  23. IceCube Alert 240204.38: Global MASTER-Net observations report
  24. Swift Trigger 1212791 is not an astrophysical event.
  25. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  26. GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
  27. Konus-Wind detection of GRB 240124B
  28. Konus-Wind detection of GRB 240123C
  29. IPN triangulation of GRB 240124B
  30. GRB 240201A: AstroSat CZTI detection
  31. GRB 240129A: Fermi GBM Observation
  32. IPN triangulation of GRB 240125B (short)
  33. GRB 240129A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  34. IPN triangulation of GRB 240125A (short)
  35. GRB 240128A: Glowbug gamma-ray detection
  36. GRB 240128A: Swift-XRT observations
  37. GRB 240128A: GRBAlpha detection
  38. GRB 240128A: Tiled Swift observations
  39. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  40. GRB 240128A: MAXI/GSC detection
  41. GRB 240125A: GRBAlpha detection
  42. Fermi GRB 240127A: Global MASTER-Net observations report
  43. GRB 240123C: GRBAlpha detection
  44. GRB 240122A: ATCA detection of radio counterpart
  45. GRB 240127A: Fermi GBM Final Real-time Localization
  46. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 240125A: CALET Gamma-Ray Burst Monitor detection
  48. Swift Trigger 1211211 and 1211212 are not astrophysical
  49. GRB 240125A: AstroSat CZTI detection of a short burst
  50. GRB 240124B: AstroSat CZTI detection
  51. GRB 240123C: AstroSat CZTI detection
  52. GRB 240125B: Fermi GBM Final Localization
  53. GRB240122A: PRIME near infrared detection
  54. GRB 240123B: Fermi GBM Observation
  55. GRB 240123A: Glowbug gamma-ray detection
  56. GRB 240125A (short): Glowbug gamma-ray detection
  57. GRB 240123B: Swift/BAT-GUANO detection of a long burst
  58. GRB 240123A: GRBAlpha detection
  59. IPN triangulation of GRB 240123C (short)
  60. Swift trigger 1210856 is not astrophysical
  61. Fermi-LAT gamma-ray observations of IceCube-240123A
  62. GRB 240123A: further SAO RAS optical observations
  63. GRB 240122B: CALET Gamma-Ray Burst Monitor detection
  64. GRB 240123A: Swift-BAT refined analysis
  65. IceCube Alert 240123.48: Global MASTER-Net observations report
  66. GRB 240123A: Mondy continued optical observations and the PL decay index
  67. GRB 240123A: SAO RAS optical observations
  68. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  69. Fermi/GBM trigger 727752941: BALROG analysis retraction
  70. GRB 240123A: Enhanced Swift-XRT position
  71. GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
  72. Fermi GRB 240123B: Global MASTER-Net observations report
  73. GRB 240122A: Swift/UVOT Upper Limits
  74. GRB 240123A: Swift-XRT refined Analysis
  75. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  76. Fermi GBM Sub-Threshold Detection of GRB 240123A
  77. GRB 240123A: Mondy continued optical observations + correction of the GRB name in GCN 35605
  78. GRB 240123B: Fermi GBM Final Real-time Localization
  79. GRB 240118A: Swift/UVOT Upper Limits
  80. GRB 240122B: Glowbug gamma-ray detection
  81. GRB 240123A: Mondy optical afterglow observations
  82. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  83. Konus-Wind detection of GRB 240112A
  84. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  85. Swift GRB240123.46: Global MASTER-Net observations report
  86. GRB 240122A: Swift-XRT afterglow detection
  87. GRB 240122A: VLT/X-shooter redshift confirmation
  88. GRB 240122A: Redshift from OSIRIS+/GTC
  89. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  90. GRB 240122A: GOTO optical counterpart candidate
  91. GRB 240122A: Tiled Swift observations
  92. Konus-Wind detection of GRB 240119A (short/hard)
  93. GRB 240122A: MAXI/GSC detection
  94. IPN triangulation of GRB 240119A (short)
  95. GRB 240119A: GECAM detection of a short burst
  96. GRB 240118C: GECAM-B detection of a long burst
  97. GRB 240119A: AstroSat CZTI detection of a short burst
  98. GRB 240118A: Mondy optical observations
  99. GRB 240118A: Swift-XRT afterglow detection
  100. GRB 240118C: Fermi GBM Observation

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