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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"

12084 results found.

  1. Fermi trigger No 701071944: Global MASTER-Net observations report
  2. SGR 1806-20: Correction to GCN 33494
  3. INTEGRAL detection of a burst from SGR 1806-200
  4. GRB 230321B: AstroSat CZTI detection
  5. GRB 230320B: AstroSat CZTI detection
  6. GRB 230320A: Fermi GBM Final Real-time Localization
  7. GRB 230314A: TURBO Optical Upper Limit
  8. Fermi trigger No 700976129: Global MASTER-Net observations report
  9. IPN triangulation of GRB 230309A
  10. Fermi GRB 230316A: Global MASTER-Net observations report
  11. GRB 230304D: AstroSat CZTI detection
  12. GRB 230313A: AstroSat CZTI detection
  13. VZLUSAT-2 detection of SGR 1806-20
  14. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  15. Fermi GRB 230313A: Global MASTER-Net observations report
  16. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  17. Further improved IPN localization for GRB 230307A
  18. Swift GRB230311.84: Global MASTER-Net observations report
  19. Trigger 1159327: Swift detection of SGR1806-20
  20. GRB 230310A: AstroSat CZTI detection
  21. GRB 230307A: GECKO optical observations and detections of the afterglow
  22. GRB 230307A: MAXI/GSC upper limit
  23. GRB 230307A: ASO-S/HXI detection
  24. GRB 230217A: ATCA rapid-response radio detection
  25. GRB 230307A: Upper limits from a neutrino search with IceCube
  26. Fermi GRB 230307A: Global MASTER-Net observations report
  27. Konus-Wind detection of GRB 230307A
  28. Fermi GRB 230308A: Global MASTER-Net observations report
  29. GRB 230307A: AstroSat CZTI detection
  30. Fermi-LAT gamma-ray observations of IceCube-230306A
  31. GRB 230307A: GECAM detection of an extremely bright burst
  32. GRB 230304C: AstroSat CZTI detection
  33. GRB 230304B: AstroSat CZTI detection
  34. GRB 230304A: AstroSat CZTI detection
  35. GRB 230304A: Fermi GBM Final Real-time Localization
  36. GRB 230228A: Swift/UVOT Upper Limits
  37. Fermi GRB 230301B: Global MASTER-Net observations report
  38. GRB 230228A: Fermi GBM Observation
  39. Fermi trigger No 699294715: Global MASTER-Net observations report
  40. GRB 230228A: Swift-XRT refined Analysis
  41. GRB 230228A: Swift detection of a possibly short burst
  42. Fermi trigger No 699029364: Global MASTER-Net observations report
  43. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  44. GRB 230216A Mondy Observations
  45. IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 230220A: Correction to GCN 33352
  47. Fermi-LAT gamma-ray observations of IceCube-230220A
  48. Fermi GRB 230220B: Global MASTER-Net observations report
  49. GRB 230217A: AstroSat CZTI detection
  50. GRB 230217A: 6 GHz VLA observations
  51. GRB 230220B: Fermi GBM Final Real-time Localization
  52. GRB 230217A: Gemini-South Optical Observation
  53. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  54. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  55. GRB 230220A: MAXI/GSC detection
  56. IceCube-230217A: BOOTES-4/MET Optical Observations
  57. Fermi-LAT gamma-ray observations of IceCube-230217A
  58. Konus-Wind detection of GRB 230217A
  59. GRB 230216B: AstroSat CZTI detection
  60. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 230216A: Swift-BAT refined analysis
  62. GRB 230216A: Swift detection of a burst
  63. Fermi trigger No 697904388: Global MASTER-Net observations report
  64. Fermi GRB 230209B: Global MASTER-Net observations report
  65. Fermi Gamma-ray Burst Monitor triggers 230206723/697396830 and 230206797/697403223 are not GRBs
  66. Fermi trigger No 697403223: Global MASTER-Net observations report
  67. Fermi trigger No 697396830: Global MASTER-Net observations report
  68. GRB 230205A: Swift-XRT refined Analysis
  69. GRB 230205A: BOOTES-5/JGT early optical upper limit
  70. GRB 230204B: AGILE detection
  71. GRB 230205A: Swift detection of a burst
  72. IceCube-230201A: BOOTES-4/MET Optical Upper Limits
  73. GRB 230204B: AstroSat CZTI detection
  74. GRB 230204B: MAXI/GSC detection
  75. Fermi trigger No 697208885: Global MASTER-Net observations report
  76. Fermi trigger No 697098930: Global MASTER-Net observations report
  77. IceCube-230201A: Upper limits from a search for additional neutrino events in IceCube
  78. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  79. Fermi GRB 230201B: Global MASTER-Net observations report
  80. Fermi-LAT gamma-ray observations of IceCube-230201A
  81. GRB 230126A: Detection by VZLUSAT-2
  82. IceCube-230201A - IceCube observation of a high-energy neutrino candidate track-like event
  83. ZTF23aaarlti/AT2023avj: Assy continued optical observations
  84. GRB 230129A: AstroSat CZTI detection
  85. IceCube-230122A: BOOTES-2/TELMA Optical Upper Limit
  86. AT2023avj ZTF Candidate: Assy optical observations
  87. GRB 230126A: Fermi GBM Final Real-time Localization
  88. GRB 230114B: Detection by VZLUSAT-2
  89. Fermi-LAT gamma-ray observations of IceCube-230122A
  90. GRB 230123A: Swift-XRT refined Analysis
  91. GRB 230123A: Swift detection of a burst
  92. GRB 230120A: AstroSat CZTI detection
  93. GRB 230116D: SAO RAS photometry
  94. Fermi GRB 230117A: Global MASTER-Net observations report
  95. GRB 230116D: GIT optical follow-up
  96. Swift GRB230116.88: Global MASTER-Net observations report
  97. Fermi-LAT gamma-ray observations of IceCube-230112A
  98. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  99. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  100. Fermi GRB 230112A: Global MASTER-Net observations report

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