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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 230307A: Erratum of the GCN 33441
  2. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  3. GRB 230308A: Fermi GBM detection
  4. GRB 230307A: Possible optical afterglow
  5. GRB 230307A: ASO-S/HXI detection
  6. GRB 230307A: AstroSat LAXPC detection
  7. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  8. GRB 230308A: AGILE/MCAL detection
  9. GRB 230307A: optical upper limit
  10. GRB 230217A: ATCA rapid-response radio detection
  11. Swift Trigger 1159108 is not a GRB
  12. GRB 230307A: Swift/BAT upper limits on the early afterglow
  13. GRB 230307A: Upper limits from a neutrino search with IceCube
  14. GRB 230307A: Swift-XRT observations
  15. Fermi GRB 230307A: Global MASTER-Net observations report
  16. Konus-Wind detection of GRB 230307A
  17. GRB 230228A: VIRT Optical Upper Limit
  18. Improved IPN localization for GRB 230307A
  19. GRB 230307A: VZLUSAT-2 detection
  20. GRB 230304B: CALET Gamma-Ray Burst Monitor detection
  21. Fermi GRB 230308A: Global MASTER-Net observations report
  22. GRB 230308A: BALROG localization (Fermi Trigger 699975152 / GRB 230308564)
  23. GRB 230308A: Fermi GBM Final Real-time Localization
  24. GRB 230307A: Tiled Swift observations
  25. GRB 230307A: Detection by GRBAlpha
  26. GRB 230305A: Detection by GRBAlpha
  27. GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  28. GRB 230307A: AstroSat CZTI detection
  29. GRB 230307A: possibly the second highest GRB energy fluence ever identified
  30. IPN triangulation of GRB 230307A (long/very bright)
  31. GRB 230307A: AGILE/MCAL detection
  32. GRB 230307A: Fermi GBM Observation of a very bright burst
  33. Solar Orbiter STIX observation of GRB 230307A
  34. IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
  35. Fermi-LAT gamma-ray observations of IceCube-230306A
  36. GRB 230307A: Fermi GBM detection of a very bright GRB
  37. GRB 230307A: GECAM detection of an extremely bright burst
  38. GRB 230307A: Fermi GBM Final Real-time Localization
  39. Fermi trigger No 699811746: Global MASTER-Net observations report
  40. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  41. IceCube Alert 230306.46: Global MASTER-Net observations report
  42. GRB 230304C: AstroSat CZTI detection
  43. GRB 230304B: AstroSat CZTI detection
  44. GRB 230304A: AstroSat CZTI detection
  45. GRB 230304B: Detection by GRBAlpha
  46. GRB 230304C: Fermi GBM Final Real-time Localization
  47. GRB 230304B: Fermi GBM Final Real-time Localization
  48. GRB 230304A: Fermi GBM Final Real-time Localization
  49. GRB 230228A: 6 GHz VLA radio upper limit
  50. GRB 230228A: Swift-BAT refined analysis
  51. GRB 230228A: Swift/UVOT Upper Limits
  52. Fermi GRB 230301B: Global MASTER-Net observations report
  53. GRB 230301B: Fermi GBM Final Real-time Localization
  54. GRB 230228A: Fermi GBM Observation
  55. Fermi trigger No 699294715: Global MASTER-Net observations report
  56. GRB 230228A: OSN optical upper limit
  57. Fermi trigger No 699311646: Global MASTER-Net observations report
  58. GRB 230301A: Fermi GBM Final Real-time Localization
  59. GRB 230228A: Swift-XRT refined Analysis
  60. GRB 230228A: Mondy optical upper limit
  61. GRB 230228A: Enhanced Swift-XRT position
  62. GRB 230228A: Nanshan/NEXT optical upper limit
  63. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  64. GRB 230228A: Prompt enhanced Swift-XRT position
  65. GRB 230228A: Swift detection of a possibly short burst
  66. Fermi GRB 230227A: Global MASTER-Net observations report
  67. GRB 230227A: Fermi GBM Final Real-time Localization
  68. Fermi trigger No 699029364: Global MASTER-Net observations report
  69. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  70. GRB 230216A Mondy Observations
  71. GRB 230205A: VLA radio afterglow confirmation
  72. IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 230217A: Swift/UVOT Upper Limits
  74. GRB 230216A: Swift/UVOT Upper Limits
  75. GRB 230217A: Continued Gemini Observations
  76. GRB 230220A: Correction to GCN 33352
  77. GRB 230222A: Fermi GBM Final Real-time Localization
  78. GRB 230217A: Swift-XRT afterglow detection
  79. Fermi-LAT gamma-ray observations of IceCube-230220A
  80. GRB 230217A: Swift-BAT refined analysis
  81. Fermi GRB 230220B: Global MASTER-Net observations report
  82. GRB 230217A: AstroSat CZTI detection
  83. GRB 230217A: Gemini South optical upper limits
  84. GRB 230216B: CALET Gamma-Ray Burst Monitor detection
  85. GRB 230217A: 6 GHz VLA observations
  86. GRB 230220B: Fermi GBM Final Real-time Localization
  87. GRB 230217A: Gemini-South Optical Observation
  88. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  89. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  90. GRB 230217A: Fermi GBM observation
  91. GRB 230220A: MAXI/GSC detection
  92. IceCube-230217A: BOOTES-4/MET Optical Observations
  93. Fermi-LAT gamma-ray observations of IceCube-230217A
  94. Konus-Wind detection of GRB 230217A
  95. GRB 230217A: Swift-XRT observations
  96. Fermi trigger No 698427992: Global MASTER-Net observations report
  97. IceCube Alert 230217.87: Global MASTER-Net observations report
  98. GRB 230218A is not a GRB
  99. GRB 230218A: Fermi GBM Final Real-time Localization
  100. GRB 230217A: AGILE/MCAL detection

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