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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 230421A: Fermi GBM observation
  2. Konus-Wind detection of GRB 230418A
  3. GRB 230420A: Swift/UVOT Upper Limits
  4. GRB 230421: Swift/BAT-GUANO arcminute localization
  5. GRB230420A: VLT optical observation
  6. GRB 230420A: Swift-BAT refined analysis
  7. Duplicate of GCN 33668
  8. GRB 230421A: Fermi GBM Final Real-time Localization
  9. GRB 230420A: Swift-XRT refined Analysis
  10. GRB 230420A: MITSuME Akeno optical observation
  11. GRB 230420A: NOT optical afterglow confirmation
  12. GRB 230420A: Gaoyazi/GOT optical upper limit
  13. GRB 230420A: BOOTES-5/JGT optical afterglow detection
  14. GRB 230420A: LCOGT Optical Upper Limit
  15. GRB 230420A: Enhanced Swift-XRT position
  16. GRB230414B: VIRT Optical Upper Limit
  17. IPN triangulation of GRB 230418A (short)
  18. GRB 230420A: Swift detection of a burst
  19. GRB 230418A: AstroSat CZTI detection
  20. GRB 230418A: AGILE detection
  21. GRB 230402A: Fermi GBM detection
  22. GRB 230419A: Fermi GBM Final Real-time Localization
  23. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  24. GRB 230418A: Fermi GBM Observation
  25. IceCube-Cascade 230417A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 230402A: Fermi-LAT detection
  27. Fermi-LAT gamma-ray observations of IceCube-230416A
  28. GRB 230414B: Nickel and KAIT telescope optical observations
  29. Duplicate of GCN 33640
  30. Duplicate of GCN 33640
  31. GRB 230414B Swift-BAT refined analysis
  32. Duplicate of GCN 33642
  33. GRB 230415A: Fermi GBM detection
  34. GRB 230414B: Swift/UVOT Detection
  35. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  36. IceCube-230416A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 230415A: Swift/BAT-GUANO detection
  38. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  39. VIRT optical transient detection
  40. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  41. GRB 230307A: iTelescope optical upper limit (likely)
  42. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  43. IceCube-230416A: IceCube observation of a high-energy neutrino candidate
  44. Fermi trigger No 703284533: Global MASTER-Net observations report
  45. GRB 230414B: Lulin 40cm-SLT optical limit
  46. GRB 230414B: Bassano Bresciano Observatory optical observations
  47. GRB 230414B: Redshift from OSIRIS/GTC
  48. GRB 230414B: AbAO optical observations
  49. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  50. GRB 230414B: Swift-XRT refined Analysis
  51. GRB 230414B: Dabancheng/GHOST optical observations
  52. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  53. GRB 230414B: slow optical light curve decay
  54. GRB 230414B: SAO RAS optical observations
  55. GRB 230414B: Enhanced Swift-XRT position
  56. GRB 230414B: 1.3m DFOT Optical observations
  57. Fermi GRB 230414A: Global MASTER-Net observations report
  58. GRB 230414B: GROWTH India Telescope afterglow confirmation
  59. GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
  60. GRB 230414B: Nanshan/HMT optical afterglow detection
  61. GRB 230414A: Mondy optical afterglow candidate
  62. Swift GRB 230414B: Global MASTER-Net observations report
  63. GRB 230414B: Prompt enhanced Swift-XRT position
  64. GRB 230414B: Swift detection of a burst
  65. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  66. GRB 230414A: Fermi GBM Final Real-time Localization
  67. GRB 230328B: redshift lower limit estimating
  68. GRB 230409B: Mondy optical upper limit
  69. GRB 230409B: OHP/T193 optical upper limit
  70. GRB 230410B: VZLUSAT-2 detection
  71. GRB 230409D: VZLUSAT-2 detection
  72. GRB 230410B: AGILE detection of a burst
  73. GRB 230410A: Fermi GBM Final Real-time Localization
  74. Fermi GRB 230409C: Global MASTER-Net observations report
  75. Fermi GRB 230409A: Global MASTER-Net observations report
  76. GRB 230409C: Fermi GBM Final Real-time Localization
  77. GRB 230409B: Swift-XRT refined Analysis
  78. GRB 230409B: Swift-BAT refined analysis
  79. Fermi trigger No 702745263: Global MASTER-Net observations report
  80. Swift GRB 230409B: Global MASTER-Net observations report
  81. GRB 230409B: Swift/UVOT Detection
  82. GRB 230409B: Enhanced Swift-XRT position
  83. MAXI GRB230408.82: Global MASTER-Net observations report
  84. GRB 230409B: Swift detection of a burst
  85. GRB 230409A: Fermi GBM Final Real-time Localization
  86. GRB 230405B: VZLUSAT-2 detection
  87. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  88. Fermi-LAT gamma-ray observations of IceCube-230405A
  89. Konus-Wind detection of GRB 230405B
  90. GRB 230405B: AGILE detection
  91. GRB 230405B: Swift-XRT refined Analysis
  92. GRB 230405B: Fermi GBM Observation
  93. GRB 230405B: MeerLICHT upper limits
  94. IceCube Alert 230405.56: Global MASTER-Net observations report
  95. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  96. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  97. GRB 230307A: good match with kilonova models
  98. GRB 230307A: short mininum variability timescale compatible with a merger origin
  99. GRB 230405B: Swift/UVOT Upper Limits
  100. GRB 230405B: AstroSat CZTI detection

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