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

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