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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"

2974 results found.

  1. Fermi GRB 250926A: Global MASTER-Net observations report
  2. Konus-Wind detection of GRB 250911A
  3. GRB 250916A: SAO RAS Zeiss-1000 optical observations
  4. GRB 250920C: Swift-BAT refined analysis
  5. GRB 250920B: Swift-BAT refined analysis
  6. GRB 250920A: Fermi GBM Final Localization
  7. Fermi GRB 250917B: Global MASTER-Net observations report
  8. GRB 250916A: GOTO optical counterpart candidate
  9. The EP-WXT trigger 01709240768 is likely a flaring star
  10. EP250911a: Global MASTER-Net observations report
  11. EP250911a: Upper limit from Fermi-GBM Observations
  12. GRB 250911A: Swift-BAT refined analysis
  13. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP#01709240653: Swift-XRT observations
  15. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  16. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  17. EP250908b: SVOM/VT optical candidate
  18. EP250908c: Global MASTER-Net observations report
  19. GRB 250903A: Swift-XRT afterglow detection
  20. IceCube Alert 250905.84: Global MASTER-Net observations report
  21. GRB 250903A: Swift/UVOT detection
  22. Swift GRB 250904A: Global MASTER-Net observations report
  23. GRB 250903A: Swift-XRT observations
  24. GRB 250903A: SVOM/VT optical confirmation with VHF data
  25. EP250901a: Mondy, Assy and SAO RAS optical limits
  26. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  27. GRB 250831A: Swift-XRT counterpart detection
  28. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  29. GRB 250830B: MAXI/GSC detection
  30. The EP-WXT trigger 01709200994 is likely a flaring star
  31. EP250828a: Global MASTER-Net observations report
  32. Fermi GRB 250827A: Global MASTER-Net observations report
  33. EP250827a: Global MASTER-Net observations report
  34. Fermi GRB 250824B: Global MASTER-Net observations report
  35. GRB 250823A: SVOM/VT optical observation
  36. GRB 250821A: KAIT optical upper limit
  37. LIGO/Virgo/KAGRA S250818k : Tautenburg observations, upper limits
  38. Fermi trigger No 776849714: Global MASTER-Net observations report
  39. GRB 250814A: Further GRAWITA TNG NIR observations
  40. Fermi trigger No 776818276: Global MASTER-Net observations report
  41. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  42. IceCube Alert 250813.14: Global MASTER-Net observations report
  43. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  44. EP250807a: COLIBRÍ optical upper limit
  45. EP250806a: Global MASTER-Net observations report
  46. GRB 250805A: Swift-BAT refined analysis
  47. GRB 250804C: AstroSat CZTI detection of a long burst
  48. GRB 250805A: Swift detection of a burst
  49. EP250711a: CrAO and Assy optical observations
  50. EP250730a: Global MASTER-Net observations report
  51. GRB 250727A: EP-FXT follow-up observation
  52. GRB 250725A: Swift-BAT refined analysis
  53. GRB 250720B: Fermi GBM Final Localization Correction
  54. Swift GRB250718.01: Global MASTER-Net observations report
  55. Fermi GRB 250716A: Global MASTER-Net observations report
  56. GRB 250706B/C: 7DT Follow-up Observations
  57. EP250711a: COLIBRÍ continuous optical observations
  58. Fermi GRB 250711A: Global MASTER-Net observations report
  59. GRB 250704B / EP250704a: VLA radio detection
  60. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  61. GRB 250702F: Leavitt Observatory optical observations
  62. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  63. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  64. GRB 250702F: Swift detection of a burst with an optical counterpart
  65. GRB 250628A: Swift detection of a burst
  66. Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
  67. GRB 250625A: Fermi GBM Final Real-time Localization
  68. Fermi GRB 250624A: Global MASTER-Net observations report
  69. Fermi GRB 250623A: Global MASTER-Net observations report
  70. Fermi trigger No 772190032: Global MASTER-Net observations report
  71. Fermi GRB 250621A: Global MASTER-Net observations report
  72. GRB 250619B: Fermi GBM Observation
  73. GRB250620C: Fermi GBM Observation
  74. EP250610a: Global MASTER-Net observations report
  75. GRB 250605A: Swift-BAT refined analysis
  76. Fermi trigger No 771072240: Global MASTER-Net observations report
  77. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  78. GRB 250527C: CrAO Optical Upper Limit
  79. EP/WXT 01709177873: GOTO observations confirm stellar variability
  80. Fermi trigger No 770867684: Global MASTER-Net observations report
  81. IPN triangulation of GRB 250529A
  82. Swift GRB250603.05: Global MASTER-Net observations report
  83. GRB 250601A: Swift/XRT candidate afterglow
  84. GRB 250601A: Swift-XRT observations
  85. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  86. GRB 250530A: SVOM/VT optical upper limit
  87. Fermi trigger No 770058372: Global MASTER-Net observations report
  88. EP250526a: Global MASTER-Net observations report
  89. Fermi trigger No 769611916: Global MASTER-Net observations report
  90. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  91. Fermi GRB 250516A: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 250512B / EP250512a
  93. Fermi GRB 250512A: Global MASTER-Net observations report
  94. EP250511a: Global MASTER-Net observations report
  95. Fermi GRB 250510C: Global MASTER-Net observations report
  96. EP250508a: REM optical/NIR observations
  97. GRB 250427B : SVOM detection of a burst through offline search
  98. GRB 250504A: Swift detection of a burst
  99. EP250428b: Global MASTER-Net observations report
  100. GRB 250424A: Swift-BAT refined analysis

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