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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-LAT gamma-ray observations of IceCube-240204A
  2. GRB 240205B: PRIME near infrared detection
  3. GRB 240205A (short): Glowbug gamma-ray detection
  4. Swift Trigger 1213872 is not an astrophysical event
  5. GRB240204A: Swift/UVOT Upper Limits
  6. GRB 240205B: AstroSat CZTI detection
  7. Fermi trigger No 729012023: Global MASTER-Net observations report
  8. GRB 240205B: Swift-BAT refined analysis
  9. Konus-Wind detection of GRB 240205B (long / very soft)
  10. GRB 240207A: Fermi GBM Final Real-time Localization
  11. Konus-Wind detection of GRB 240125A
  12. GRB 240205B: VLT/X-shooter redshift
  13. GRB 240205B: CALET Gamma-Ray Burst Monitor detection
  14. GRB 240205B: BOOTES-6 optical afterglow follow-up
  15. GRB 240205B: ATCA detection of radio counterpart
  16. GRB 240205B: REM detection of the optical/NIR afterglow
  17. GRB 240205B: Fermi GBM Observation
  18. GRB 240204A: AstroSat CZTI detection
  19. GRB 240204A: Mondy optical afterglow observations
  20. GRB 240204A : OHP/T193/T120 optical afterglow fading detection
  21. GRB 240205B: GECAM detection of a long burst
  22. GRB 240204A: Swift-BAT refined analysis
  23. GRB 240205B: Skynet Optical Afterglow Observations
  24. GRB 240205B: BOOTES-7 optical afterglow follow-up
  25. Fermi trigger No 728749569: Global MASTER-Net observations report
  26. GRB 240205B: MASTER OT J232550.14-550704.6 counterpart detection
  27. GRB 240205B: Swift detection of a burst
  28. GRB 240205B: Fermi GBM Final Real-time Localization
  29. Swift GRB240205.93: Global MASTER-Net observations report
  30. GRB 240204A: Fermi GBM Observation
  31. GRB 240205A: Fermi GBM Final Real-time Localization
  32. GRB 240204a: Liverpool Telescope optical afterglow detection
  33. GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
  34. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  35. Fermi Gamma-ray Burst Monitor trigger 728740048/240204491 is not a GRB
  36. Fermi trigger No 728796365: Global MASTER-Net observations report
  37. GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
  38. GRB 240204A: Montarrenti Observatory optical observations
  39. GRB 240204A: Enhanced Swift-XRT position
  40. GRB 240204A: Mondy optical afterglow candidate
  41. Fermi Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
  42. Fermi GRB 240204A: Global MASTER-Net observations report
  43. Fermi trigger No 728706420: Global MASTER-Net observations report
  44. GRB 240204A: Swift detection of a burst
  45. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 240204A: Fermi GBM Final Real-time Localization
  47. IceCube Alert 240204.38: Global MASTER-Net observations report
  48. Swift Trigger 1212791 is not an astrophysical event.
  49. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  50. GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
  51. Konus-Wind detection of GRB 240124B
  52. Konus-Wind detection of GRB 240123C
  53. IPN triangulation of GRB 240124B
  54. GRB 240201A: AstroSat CZTI detection
  55. GRB 240129A: Fermi GBM Observation
  56. IPN triangulation of GRB 240125B (short)
  57. GRB 240129A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  58. IPN triangulation of GRB 240125A (short)
  59. GRB 240128A: Glowbug gamma-ray detection
  60. GRB 240128A: Swift-XRT observations
  61. GRB 240128A: GRBAlpha detection
  62. GRB 240128A: Tiled Swift observations
  63. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  64. GRB 240128A: MAXI/GSC detection
  65. GRB 240125A: GRBAlpha detection
  66. Fermi GRB 240127A: Global MASTER-Net observations report
  67. GRB 240123C: GRBAlpha detection
  68. GRB 240122A: ATCA detection of radio counterpart
  69. GRB 240127A: Fermi GBM Final Real-time Localization
  70. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  71. GRB 240125A: CALET Gamma-Ray Burst Monitor detection
  72. Swift Trigger 1211211 and 1211212 are not astrophysical
  73. GRB 240125A: AstroSat CZTI detection of a short burst
  74. GRB 240124B: AstroSat CZTI detection
  75. GRB 240123C: AstroSat CZTI detection
  76. GRB 240125B: Fermi GBM Final Localization
  77. GRB240122A: PRIME near infrared detection
  78. GRB 240123B: Fermi GBM Observation
  79. GRB 240123A: Glowbug gamma-ray detection
  80. GRB 240125A (short): Glowbug gamma-ray detection
  81. GRB 240123B: Swift/BAT-GUANO detection of a long burst
  82. GRB 240123A: GRBAlpha detection
  83. IPN triangulation of GRB 240123C (short)
  84. Swift trigger 1210856 is not astrophysical
  85. Fermi-LAT gamma-ray observations of IceCube-240123A
  86. GRB 240123A: further SAO RAS optical observations
  87. GRB 240122B: CALET Gamma-Ray Burst Monitor detection
  88. GRB 240123A: Swift-BAT refined analysis
  89. IceCube Alert 240123.48: Global MASTER-Net observations report
  90. GRB 240123A: Mondy continued optical observations and the PL decay index
  91. GRB 240123A: SAO RAS optical observations
  92. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  93. Fermi/GBM trigger 727752941: BALROG analysis retraction
  94. GRB 240123A: Enhanced Swift-XRT position
  95. GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
  96. Fermi GRB 240123B: Global MASTER-Net observations report
  97. GRB 240122A: Swift/UVOT Upper Limits
  98. GRB 240123A: Swift-XRT refined Analysis
  99. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  100. Fermi GBM Sub-Threshold Detection of GRB 240123A

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