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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"

27811 results found.

  1. Swift GRB 250924A: Global MASTER-Net observations report
  2. GRB 250924A: DDOTI Detection of the Optical Counterpart
  3. GRB 250924A: Swift detection of a burst with an optical counterpart
  4. GRB 250920B: AbAO optical upper limits
  5. Konus-Wind detection of GRB 250920C
  6. GRB 250920C: VLT redshift confirmation z = 1.399
  7. GRB 250920B: CrAO ZTSH optical observations
  8. GRB 250920C: COLIBRÍ optical observations
  9. GRB 250922C: AstroSat CZTI detection of a short burst
  10. GRB 250922B: Fermi GBM Final Real-time Localization
  11. GRB 250920C: PRIME near-infrared detection
  12. Konus-Wind detection of GRB 250920B
  13. Konus-Wind detection of GRB 250920A
  14. IPN triangulation of GRB 250920A (long/bright)
  15. Konus-Wind detection of GRB 250911A
  16. GRB 250916A: Swift/UVOT Detection
  17. GRB 250920B: Glowbug gamma-ray detection
  18. GRB 250920C: Swift-XRT refined Analysis
  19. GRB 250922A: Fermi GBM Final Localization
  20. GRB 250920B: Kitab-ISON optical upper limit
  21. GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
  22. GRB 250920C: SVOM/GRM observation
  23. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  24. GRB 250917B: KAIT optical upper limit
  25. GRB 250920A: NuSTAR detection of bright prompt emission
  26. GRB 250920C: GROWTH-India Telescope optical observations
  27. GRB 250920C: Swift-BAT refined analysis
  28. GRB 250920B: Swift-BAT refined analysis
  29. GRB 250920C: Enhanced Swift-XRT position
  30. GRB 250920C: Swift/UVOT Detection
  31. GRB 250920B: Fermi GBM Observation
  32. GRB 250920A: Fermi GBM Detection
  33. GRB 250920C: Fermi GBM Observation
  34. Swift GRB 250920C: Global MASTER-Net observations report
  35. GRB 250920B: Swift/UVOT Detection
  36. GRB 250920C: Optical counterpart detection by LCO
  37. GRB250920C: LCOGT Optical Detection
  38. GRB 250920B: Enhanced Swift-XRT position
  39. GRB 250920B: Swift-XRT refined Analysis
  40. GRB 250920B: SVOM/C-GFT optical observations
  41. GRB 250920C: GOTO optical counterpart candidate
  42. Konus-Wind detection of GRB 250919A
  43. GRB 250920C: Swift detection of a burst
  44. GRB 250920C: Fermi GBM Final Real-time Localization
  45. Swift GRB 250920B: Global MASTER-Net observations report
  46. GRB 250919A / EP250919a: Insight-HXMT detection
  47. GRB 250920A: AstroSat CZTI detection
  48. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  49. GRB 250920B: Fermi GBM Final Real-time Localization
  50. GRB 250920A: Fermi GBM Final Localization
  51. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  52. GRB 250916A: Mondy R-band optical observations
  53. GRB 250919A: Glowbug gamma-ray detection
  54. GRB 250919A: Fermi GBM Observation
  55. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  56. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  57. GRB 250919A: Swift-XRT afterglow detection
  58. GRB 250919A: Fermi-LAT detection
  59. EP250919a: Einstein Probe detection of an X-ray transient
  60. GRB 250919A: Fermi GBM Final Real-time Localization
  61. GRB 250916A: NuSTAR detection of the prompt emission
  62. GRB 250917B: Swift-BAT refined analysis
  63. GRB 250918A: Fermi GBM Final Real-time Localization
  64. GRB 250917B: Swift/UVOT Upper Limits
  65. GRB 250916A: Swift-XRT observations
  66. EP250916a: EP-FXT follow-up observation
  67. GRB 250916A: Glowbug gamma-ray detection
  68. GRB250917B: WFST optical observations
  69. GRB 250916A: Swift ToO observations
  70. GRB 250917B: Fermi GBM Observation
  71. GRB 250917B: Swift-XRT observations
  72. GRB 250917B: Swift detection of a short burst
  73. GRB 250916A: GOTO optical counterpart candidate
  74. GRB 250917B: Fermi GBM Final Real-time Localization
  75. GRB 250917A: Fermi GBM Final Real-time Localization
  76. GRB 250916A: AstroSat CZTI detection of a bright long burst
  77. EP250916a: Einstein Probe detection of an X-ray transient
  78. GRB 250916A: Fermi GBM Final Real-time Localization
  79. SVOM/sb25091517: SVOM detection of an X-ray transient
  80. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  81. GRB 250912A: Swift-XRT observations
  82. GRB 250912A: VLT observations
  83. GRB 250911A: Insight-HXMT detection
  84. GRB 250912A: SVOM detection of a burst
  85. GRB 250912A: Fermi GBM Final Real-time Localization
  86. GRB 250911A: GECAM-B detection
  87. GRB 250911A: Swift-BAT refined analysis
  88. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  89. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  90. EP250911a: SVOM/VT optical observation
  91. GRB 250911A: MASTER optical counterpart observations
  92. GRB 250911A: Swift-XRT refined Analysis
  93. GRB 250910C: Fermi GBM Final Localization Correction
  94. EP250911a: Swift-XRT observations
  95. EP250911a: Optical detection with Kinder observations
  96. GRB 250911A: Swift/UVOT Detection
  97. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  98. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  99. GRB 250909B: Insight-HXMT detection
  100. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery

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