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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. IceCube-230506A: IceCube observation of a high-energy neutrino candidate
  2. GRB 230506C: Swift detection of a burst
  3. Swift GRB230506.71: Global MASTER-Net observations report
  4. GRB 230506B: Swift detection of a burst
  5. GRB 230506B: MASTER optical observations
  6. GRB 230506B: Swift detection of a burst
  7. GRB 230506A: Fermi GBM Final Real-time Localization
  8. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  9. Fermi trigger No 704837952: Global MASTER-Net observations report
  10. GRB 230430A: A short GRB from a neutron star merger
  11. GRB 230427A: Swift-BAT refined analysis
  12. GRB 230503A: Fermi GBM Final Real-time Localization
  13. Konus-Wind detection of GRB 230430A
  14. IceCube-Cascade 230430A: Upper limits from a search for additional neutrino events in IceCube
  15. IPN triangulation of GRB 230430A (short)
  16. GRB 230420A: AROMA-N Optical Upper Limit
  17. GRB 230430B: Fermi GBM Final Localization
  18. GRB 230430A: Fermi GBM observation
  19. GRB 230430A: AstroSat CZTI detection
  20. GRB 230430A: Fermi GBM Final Real-time Localization
  21. GRB 230427A: NOT optical upper limit
  22. GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
  23. GRB 230427A: Swift/UVOT Detection
  24. Duplicate of GCN 33369
  25. GRB 230427A: Gaoyazi/GOT optical upper limit
  26. GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
  27. GRB 230427A: Nanshan/HMT optical upper limit
  28. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  29. GRB 230427A: OSIRIS+/GTC observations
  30. GRB 230427A: Swift-XRT refined Analysis
  31. GRB 230426A: VZLUSAT-2 detection
  32. Fermi trigger No 704365743: Global MASTER-Net observations report
  33. GRB 230428A: Fermi GBM Final Real-time Localization
  34. GRB 230427A: GIT optical upper limit
  35. GRB 230427A: Bassano Bresciano Observatory upper limit
  36. GRB 230427A: GMG upper limit
  37. GRB 230427A : OHP/T193 optical upper limit
  38. GRB 230427A: BOOTES-5/JGT afterglow detection
  39. GRB 230423A(trigger #1165354): Swift-BAT refined analysis
  40. GRB 230427A: AKO Upper Limit
  41. Swift GRB230427.44: Global MASTER-Net observations report
  42. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  43. GRB 230427A: MITSuME Akeno optical upper limits
  44. GRB 230426A: Fermi GBM Detection
  45. GRB 230427A: Enhanced Swift-XRT position
  46. GRB 230427A: Swift detection of a burst with an optical counterpart
  47. GRB 230426A: AstroSat CZTI detection
  48. Fermi trigger No 704233744: Global MASTER-Net observations report
  49. GRB 230426A: Fermi GBM Final Real-time Localization
  50. GRB 230423A: Swift/UVOT Upper Limits
  51. GRB 230425A: Fermi GBM Final Real-time Localization
  52. GRB 230423A: Swift-XRT refined Analysis
  53. GRB 230420A: Lowell Discovery Telescope Optical Detection
  54. GRB 230423A: Swift-XRT afterglow detection
  55. Erroneous submission
  56. Swift Trigger 1165354 is probably not a GRB
  57. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  58. GRB 230421A: Fermi GBM observation
  59. Konus-Wind detection of GRB 230418A
  60. GRB 230420A: Swift/UVOT Upper Limits
  61. GRB 230421: Swift/BAT-GUANO arcminute localization
  62. GRB230420A: VLT optical observation
  63. GRB 230420A: Swift-BAT refined analysis
  64. Duplicate of GCN 33668
  65. GRB 230421A: Fermi GBM Final Real-time Localization
  66. GRB 230420A: Swift-XRT refined Analysis
  67. GRB 230420A: MITSuME Akeno optical observation
  68. GRB 230420A: NOT optical afterglow confirmation
  69. GRB 230420A: Gaoyazi/GOT optical upper limit
  70. GRB 230420A: BOOTES-5/JGT optical afterglow detection
  71. GRB 230420A: LCOGT Optical Upper Limit
  72. GRB 230420A: Enhanced Swift-XRT position
  73. GRB230414B: VIRT Optical Upper Limit
  74. IPN triangulation of GRB 230418A (short)
  75. GRB 230420A: Swift detection of a burst
  76. GRB 230418A: AstroSat CZTI detection
  77. GRB 230418A: AGILE detection
  78. GRB 230402A: Fermi GBM detection
  79. GRB 230419A: Fermi GBM Final Real-time Localization
  80. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  81. GRB 230418A: Fermi GBM Observation
  82. IceCube-Cascade 230417A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 230402A: Fermi-LAT detection
  84. Fermi-LAT gamma-ray observations of IceCube-230416A
  85. GRB 230414B: Nickel and KAIT telescope optical observations
  86. Duplicate of GCN 33640
  87. Duplicate of GCN 33640
  88. GRB 230414B Swift-BAT refined analysis
  89. Duplicate of GCN 33642
  90. GRB 230415A: Fermi GBM detection
  91. GRB 230414B: Swift/UVOT Detection
  92. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  93. IceCube-230416A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 230415A: Swift/BAT-GUANO detection
  95. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  96. VIRT optical transient detection
  97. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  98. GRB 230307A: iTelescope optical upper limit (likely)
  99. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  100. IceCube-230416A: IceCube observation of a high-energy neutrino candidate

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