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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 Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
  2. Fermi GRB 240204A: Global MASTER-Net observations report
  3. Fermi trigger No 728706420: Global MASTER-Net observations report
  4. GRB 240204A: Swift detection of a burst
  5. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  6. GRB 240204A: Fermi GBM Final Real-time Localization
  7. IceCube Alert 240204.38: Global MASTER-Net observations report
  8. Swift Trigger 1212791 is not an astrophysical event.
  9. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  10. GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
  11. Konus-Wind detection of GRB 240124B
  12. Konus-Wind detection of GRB 240123C
  13. IPN triangulation of GRB 240124B
  14. GRB 240201A: AstroSat CZTI detection
  15. GRB 240129A: Fermi GBM Observation
  16. IPN triangulation of GRB 240125B (short)
  17. GRB 240129A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  18. IPN triangulation of GRB 240125A (short)
  19. GRB 240128A: Glowbug gamma-ray detection
  20. GRB 240128A: Swift-XRT observations
  21. GRB 240128A: GRBAlpha detection
  22. GRB 240128A: Tiled Swift observations
  23. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  24. GRB 240128A: MAXI/GSC detection
  25. GRB 240125A: GRBAlpha detection
  26. Fermi GRB 240127A: Global MASTER-Net observations report
  27. GRB 240123C: GRBAlpha detection
  28. GRB 240122A: ATCA detection of radio counterpart
  29. GRB 240127A: Fermi GBM Final Real-time Localization
  30. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 240125A: CALET Gamma-Ray Burst Monitor detection
  32. Swift Trigger 1211211 and 1211212 are not astrophysical
  33. GRB 240125A: AstroSat CZTI detection of a short burst
  34. GRB 240124B: AstroSat CZTI detection
  35. GRB 240123C: AstroSat CZTI detection
  36. GRB 240125B: Fermi GBM Final Localization
  37. GRB240122A: PRIME near infrared detection
  38. GRB 240123B: Fermi GBM Observation
  39. GRB 240123A: Glowbug gamma-ray detection
  40. GRB 240125A (short): Glowbug gamma-ray detection
  41. GRB 240123B: Swift/BAT-GUANO detection of a long burst
  42. GRB 240123A: GRBAlpha detection
  43. IPN triangulation of GRB 240123C (short)
  44. Swift trigger 1210856 is not astrophysical
  45. Fermi-LAT gamma-ray observations of IceCube-240123A
  46. GRB 240123A: further SAO RAS optical observations
  47. GRB 240122B: CALET Gamma-Ray Burst Monitor detection
  48. GRB 240123A: Swift-BAT refined analysis
  49. IceCube Alert 240123.48: Global MASTER-Net observations report
  50. GRB 240123A: Mondy continued optical observations and the PL decay index
  51. GRB 240123A: SAO RAS optical observations
  52. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  53. Fermi/GBM trigger 727752941: BALROG analysis retraction
  54. GRB 240123A: Enhanced Swift-XRT position
  55. GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
  56. Fermi GRB 240123B: Global MASTER-Net observations report
  57. GRB 240122A: Swift/UVOT Upper Limits
  58. GRB 240123A: Swift-XRT refined Analysis
  59. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  60. Fermi GBM Sub-Threshold Detection of GRB 240123A
  61. GRB 240123A: Mondy continued optical observations + correction of the GRB name in GCN 35605
  62. GRB 240123B: Fermi GBM Final Real-time Localization
  63. GRB 240118A: Swift/UVOT Upper Limits
  64. GRB 240122B: Glowbug gamma-ray detection
  65. GRB 240123A: Mondy optical afterglow observations
  66. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  67. Konus-Wind detection of GRB 240112A
  68. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  69. Swift GRB240123.46: Global MASTER-Net observations report
  70. GRB 240122A: Swift-XRT afterglow detection
  71. GRB 240122A: VLT/X-shooter redshift confirmation
  72. GRB 240122A: Redshift from OSIRIS+/GTC
  73. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  74. GRB 240122A: GOTO optical counterpart candidate
  75. GRB 240122A: Tiled Swift observations
  76. Konus-Wind detection of GRB 240119A (short/hard)
  77. GRB 240122A: MAXI/GSC detection
  78. IPN triangulation of GRB 240119A (short)
  79. GRB 240119A: GECAM detection of a short burst
  80. GRB 240118C: GECAM-B detection of a long burst
  81. GRB 240119A: AstroSat CZTI detection of a short burst
  82. GRB 240118A: Mondy optical observations
  83. GRB 240118A: Swift-XRT afterglow detection
  84. GRB 240118C: Fermi GBM Observation
  85. Fermi GRB 240119A: Global MASTER-Net observations report
  86. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  87. GRB 240119A: Fermi GBM Final Localization
  88. GRB 240117A: CALET Gamma-Ray Burst Monitor detection
  89. GRB 240118C: Swift/BAT-GUANO detection of a burst
  90. GRB 240118A: GRBAlpha detection
  91. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A: correction on the localization
  92. GRB 240115A: Fermi GBM Observation
  93. Swift triggers 1209631, 1209632, 1209635 and 1209644 are not interesting astrophysical events
  94. GRB 240118C: Fermi GBM Final Localization
  95. GRB 240118D: AstroSat CZTI detection
  96. GRB 240117A: AstroSat CZTI detection
  97. GRB 240118A: Swift ToO observations
  98. GRB 240118A: AbAO optical upper limit
  99. Fermi GRB 240118B: Global MASTER-Net observations report
  100. GRB 240118A: NuSTAR Offline Analysis of the GRB

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