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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. IPN triangulation of GRB 240125A (short)
  2. GRB 240128A: Glowbug gamma-ray detection
  3. GRB 240128A: Swift-XRT observations
  4. GRB 240128A: GRBAlpha detection
  5. GRB 240128A: Tiled Swift observations
  6. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  7. GRB 240128A: MAXI/GSC detection
  8. GRB 240125A: GRBAlpha detection
  9. Fermi GRB 240127A: Global MASTER-Net observations report
  10. GRB 240123C: GRBAlpha detection
  11. GRB 240122A: ATCA detection of radio counterpart
  12. GRB 240127A: Fermi GBM Final Real-time Localization
  13. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 240125A: CALET Gamma-Ray Burst Monitor detection
  15. Swift Trigger 1211211 and 1211212 are not astrophysical
  16. GRB 240125A: AstroSat CZTI detection of a short burst
  17. GRB 240124B: AstroSat CZTI detection
  18. GRB 240123C: AstroSat CZTI detection
  19. GRB 240125B: Fermi GBM Final Localization
  20. GRB240122A: PRIME near infrared detection
  21. GRB 240123B: Fermi GBM Observation
  22. GRB 240123A: Glowbug gamma-ray detection
  23. GRB 240125A (short): Glowbug gamma-ray detection
  24. GRB 240123B: Swift/BAT-GUANO detection of a long burst
  25. GRB 240123A: GRBAlpha detection
  26. IPN triangulation of GRB 240123C (short)
  27. Swift trigger 1210856 is not astrophysical
  28. Fermi-LAT gamma-ray observations of IceCube-240123A
  29. GRB 240123A: further SAO RAS optical observations
  30. GRB 240122B: CALET Gamma-Ray Burst Monitor detection
  31. GRB 240123A: Swift-BAT refined analysis
  32. IceCube Alert 240123.48: Global MASTER-Net observations report
  33. GRB 240123A: Mondy continued optical observations and the PL decay index
  34. GRB 240123A: SAO RAS optical observations
  35. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  36. Fermi/GBM trigger 727752941: BALROG analysis retraction
  37. GRB 240123A: Enhanced Swift-XRT position
  38. GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
  39. Fermi GRB 240123B: Global MASTER-Net observations report
  40. GRB 240122A: Swift/UVOT Upper Limits
  41. GRB 240123A: Swift-XRT refined Analysis
  42. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  43. Fermi GBM Sub-Threshold Detection of GRB 240123A
  44. GRB 240123A: Mondy continued optical observations + correction of the GRB name in GCN 35605
  45. GRB 240123B: Fermi GBM Final Real-time Localization
  46. GRB 240118A: Swift/UVOT Upper Limits
  47. GRB 240122B: Glowbug gamma-ray detection
  48. GRB 240123A: Mondy optical afterglow observations
  49. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  50. Konus-Wind detection of GRB 240112A
  51. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  52. Swift GRB240123.46: Global MASTER-Net observations report
  53. GRB 240122A: Swift-XRT afterglow detection
  54. GRB 240122A: VLT/X-shooter redshift confirmation
  55. GRB 240122A: Redshift from OSIRIS+/GTC
  56. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  57. GRB 240122A: GOTO optical counterpart candidate
  58. GRB 240122A: Tiled Swift observations
  59. Konus-Wind detection of GRB 240119A (short/hard)
  60. GRB 240122A: MAXI/GSC detection
  61. IPN triangulation of GRB 240119A (short)
  62. GRB 240119A: GECAM detection of a short burst
  63. GRB 240118C: GECAM-B detection of a long burst
  64. GRB 240119A: AstroSat CZTI detection of a short burst
  65. GRB 240118A: Mondy optical observations
  66. GRB 240118A: Swift-XRT afterglow detection
  67. GRB 240118C: Fermi GBM Observation
  68. Fermi GRB 240119A: Global MASTER-Net observations report
  69. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  70. GRB 240119A: Fermi GBM Final Localization
  71. GRB 240117A: CALET Gamma-Ray Burst Monitor detection
  72. GRB 240118C: Swift/BAT-GUANO detection of a burst
  73. GRB 240118A: GRBAlpha detection
  74. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A: correction on the localization
  75. GRB 240115A: Fermi GBM Observation
  76. Swift triggers 1209631, 1209632, 1209635 and 1209644 are not interesting astrophysical events
  77. GRB 240118C: Fermi GBM Final Localization
  78. GRB 240118D: AstroSat CZTI detection
  79. GRB 240117A: AstroSat CZTI detection
  80. GRB 240118A: Swift ToO observations
  81. GRB 240118A: AbAO optical upper limit
  82. Fermi GRB 240118B: Global MASTER-Net observations report
  83. GRB 240118A: NuSTAR Offline Analysis of the GRB
  84. GRB 240117A: Glowbug gamma-ray detection
  85. GRB 240118A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  86. Konus-Wind detection of GRB 240118A
  87. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A
  88. GRB 240118C: BALROG localization (Fermi Trigger 727291408 / GRB 240118725)
  89. GRB 240118A: NuSTAR Detection of a Long GRB
  90. GRB 240118A: Fermi GBM Observation
  91. GRB 240118B: Fermi GBM Final Real-time Localization
  92. LAT GRB240118.08: Global MASTER-Net observations report
  93. GRB 240118A: Fermi-LAT detection
  94. GRID detection of GRB 231230A
  95. GRB 240118A: Fermi GBM Final Real-time Localization
  96. GRB 240115A: Swift/BAT-GUANO detection of a short burst
  97. Swift Trigger 1209406 is not an astrophysical event
  98. Swift Triggers 1209401 and 1209403 are not astrophysical events
  99. IPN triangulation of GRB 240112A (long)
  100. Swift Triggers 1209371 through 1209374 are not astrophysical events

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