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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 240129A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  2. IPN triangulation of GRB 240125A (short)
  3. GRB 240128A: Glowbug gamma-ray detection
  4. GRB 240128A: Swift-XRT observations
  5. GRB 240128A: GRBAlpha detection
  6. GRB 240128A: Tiled Swift observations
  7. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  8. GRB 240128A: MAXI/GSC detection
  9. GRB 240125A: GRBAlpha detection
  10. Fermi GRB 240127A: Global MASTER-Net observations report
  11. GRB 240123C: GRBAlpha detection
  12. GRB 240122A: ATCA detection of radio counterpart
  13. GRB 240127A: Fermi GBM Final Real-time Localization
  14. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 240125A: CALET Gamma-Ray Burst Monitor detection
  16. Swift Trigger 1211211 and 1211212 are not astrophysical
  17. GRB 240125A: AstroSat CZTI detection of a short burst
  18. GRB 240124B: AstroSat CZTI detection
  19. GRB 240123C: AstroSat CZTI detection
  20. GRB 240125B: Fermi GBM Final Localization
  21. GRB240122A: PRIME near infrared detection
  22. GRB 240123B: Fermi GBM Observation
  23. GRB 240123A: Glowbug gamma-ray detection
  24. GRB 240125A (short): Glowbug gamma-ray detection
  25. GRB 240123B: Swift/BAT-GUANO detection of a long burst
  26. GRB 240123A: GRBAlpha detection
  27. IPN triangulation of GRB 240123C (short)
  28. Swift trigger 1210856 is not astrophysical
  29. Fermi-LAT gamma-ray observations of IceCube-240123A
  30. GRB 240123A: further SAO RAS optical observations
  31. GRB 240122B: CALET Gamma-Ray Burst Monitor detection
  32. GRB 240123A: Swift-BAT refined analysis
  33. IceCube Alert 240123.48: Global MASTER-Net observations report
  34. GRB 240123A: Mondy continued optical observations and the PL decay index
  35. GRB 240123A: SAO RAS optical observations
  36. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  37. Fermi/GBM trigger 727752941: BALROG analysis retraction
  38. GRB 240123A: Enhanced Swift-XRT position
  39. GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
  40. Fermi GRB 240123B: Global MASTER-Net observations report
  41. GRB 240122A: Swift/UVOT Upper Limits
  42. GRB 240123A: Swift-XRT refined Analysis
  43. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  44. Fermi GBM Sub-Threshold Detection of GRB 240123A
  45. GRB 240123A: Mondy continued optical observations + correction of the GRB name in GCN 35605
  46. GRB 240123B: Fermi GBM Final Real-time Localization
  47. GRB 240118A: Swift/UVOT Upper Limits
  48. GRB 240122B: Glowbug gamma-ray detection
  49. GRB 240123A: Mondy optical afterglow observations
  50. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  51. Konus-Wind detection of GRB 240112A
  52. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  53. Swift GRB240123.46: Global MASTER-Net observations report
  54. GRB 240122A: Swift-XRT afterglow detection
  55. GRB 240122A: VLT/X-shooter redshift confirmation
  56. GRB 240122A: Redshift from OSIRIS+/GTC
  57. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  58. GRB 240122A: GOTO optical counterpart candidate
  59. GRB 240122A: Tiled Swift observations
  60. Konus-Wind detection of GRB 240119A (short/hard)
  61. GRB 240122A: MAXI/GSC detection
  62. IPN triangulation of GRB 240119A (short)
  63. GRB 240119A: GECAM detection of a short burst
  64. GRB 240118C: GECAM-B detection of a long burst
  65. GRB 240119A: AstroSat CZTI detection of a short burst
  66. GRB 240118A: Mondy optical observations
  67. GRB 240118A: Swift-XRT afterglow detection
  68. GRB 240118C: Fermi GBM Observation
  69. Fermi GRB 240119A: Global MASTER-Net observations report
  70. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  71. GRB 240119A: Fermi GBM Final Localization
  72. GRB 240117A: CALET Gamma-Ray Burst Monitor detection
  73. GRB 240118C: Swift/BAT-GUANO detection of a burst
  74. GRB 240118A: GRBAlpha detection
  75. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A: correction on the localization
  76. GRB 240115A: Fermi GBM Observation
  77. Swift triggers 1209631, 1209632, 1209635 and 1209644 are not interesting astrophysical events
  78. GRB 240118C: Fermi GBM Final Localization
  79. GRB 240118D: AstroSat CZTI detection
  80. GRB 240117A: AstroSat CZTI detection
  81. GRB 240118A: Swift ToO observations
  82. GRB 240118A: AbAO optical upper limit
  83. Fermi GRB 240118B: Global MASTER-Net observations report
  84. GRB 240118A: NuSTAR Offline Analysis of the GRB
  85. GRB 240117A: Glowbug gamma-ray detection
  86. GRB 240118A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  87. Konus-Wind detection of GRB 240118A
  88. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A
  89. GRB 240118C: BALROG localization (Fermi Trigger 727291408 / GRB 240118725)
  90. GRB 240118A: NuSTAR Detection of a Long GRB
  91. GRB 240118A: Fermi GBM Observation
  92. GRB 240118B: Fermi GBM Final Real-time Localization
  93. LAT GRB240118.08: Global MASTER-Net observations report
  94. GRB 240118A: Fermi-LAT detection
  95. GRID detection of GRB 231230A
  96. GRB 240118A: Fermi GBM Final Real-time Localization
  97. GRB 240115A: Swift/BAT-GUANO detection of a short burst
  98. Swift Trigger 1209406 is not an astrophysical event
  99. Swift Triggers 1209401 and 1209403 are not astrophysical events
  100. IPN triangulation of GRB 240112A (long)

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