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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 191031D: Chandra upper limit
  2. Swift trigger 933276 MASTER observation
  3. Fermi trigger No 594592184: Global MASTER-Net observations report
  4. Fermi trigger No 594523229: Global MASTER-Net observations report
  5. Trigger 933285: Swift detection of the brightest burst so far from SGR 1935+2154
  6. Swift GRB191105.01: Global MASTER-Net observations report
  7. Trigger 933276: Swift detection of further activity from SGR 1935+2154
  8. Swift GRB191105.01: Global MASTER-Net OT detection
  9. GRB 191101A: Swift-BAT refined analysis
  10. Fermi GBM GRB 191104C (trigger 594592184 / 191104854) is not a GRB
  11. GRB 191104C: Fermi GBM Final Real-time Localization
  12. GRB 191101A: Swift/UVOT Upper Limits
  13. Fermi GBM GRBs 191104 A, B, C and triggers 594534420/191104185 and 594563923/191104527 are not GRBs
  14. SGR 1935+2154: Swift-BAT refined analysis
  15. Fermi trigger No 594563923: Global MASTER-Net observations report
  16. GRB 191104B/GRB 191104C are SGR 1935+2154
  17. Fermi trigger No 594557071: Global MASTER-Net observations report
  18. GRB 191104C: BALROG localization (Fermi Trigger 594557071 / GRB 191104448)
  19. GRB 191104C: Fermi GBM Final Real-time Localization
  20. Fermi trigger No 594551878: Global MASTER-Net observations report
  21. Fermi trigger No 594528816: Global MASTER-Net observations report
  22. GRB 191104B: Fermi GBM Final Real-time Localization
  23. Trigger 933083: Swift detection of SGR 1935+2154
  24. Fermi GBM triggers 594523229/191104056 and 594528816/191104120 are not GRBs
  25. GRB 191104A: Fermi GBM Final Real-time Localization
  26. GRB 191031D: Zwicky Transient Facility Follow-Up of a Swift Short GRB (Trigger 594249816/191031891)
  27. Konus-Wind observation of GRB 191031D: correction to GCN 26126
  28. GRB 191031E: Insight-HXMT/HE detection
  29. GRB 191031D: Gemini optical upper limit
  30. GRB 191031C: Insight-HXMT/HE detection
  31. GRB 191101A: iTelescope optical limit
  32. GRB 191101A: Swift-XRT refined Analysis
  33. Baksan Neutrino Observatory Alert 191102.06: Global MASTER-Net observations report
  34. GRB 191101A: VIRT Optical Upper Limits
  35. Fermi trigger No 594336535: Global MASTER-Net observations report
  36. GRB 191101A: Enhanced Swift-XRT position
  37. Swift GRB191101.88: Global MASTER-Net observations report
  38. Fermi trigger No 594227699: Global MASTER-Net observations report
  39. GRB 191101A: Prompt enhanced Swift-XRT position
  40. GRB 191101B: Fermi GBM Final Real-time Localization
  41. GRB 191101A: Swift detection of a burst
  42. GRB 191031D: MMT Binospec Optical Upper Limit
  43. GRB 191031D: Swift-BAT refined analysis
  44. GRB 191031C: Swift-BAT refined analysis
  45. GRB 191031A: Swift-BAT refined analysis
  46. GRB 191031C: Swift-XRT refined Analysis
  47. GRB 191031D: AstroSat CZTI detection
  48. GRB 191031D: Swift/UVOT Upper Limits
  49. GRB 191031C: Swift/UVOT Detection
  50. Konus-Wind observation of GRB 191031D
  51. GRB 191031D: MITSuME Akeno optical upper limits
  52. GRB 191031D: Swift-XRT refined Analysis
  53. GRB 191031D: AGILE/MCAL observations
  54. GRB 191031D: COATLI Optical Observations
  55. GRB 191031D: RATIR Optical and NIR Observations
  56. GRB 191031D: VLA 9.8 GHz upper limit
  57. GRB 191031C: Fermi GBM detection
  58. GRB 191031D: Fermi GBM detection
  59. GRB 191031D: Enhanced Swift-XRT position
  60. GRB 191031A: Fermi GBM detection
  61. GRB 191031C: Enhanced Swift-XRT position
  62. Correction in name: GRB 191031D (not GRB 191031C)
  63. Swift GRB191031.89: Global MASTER-Net observations report
  64. GRB 191031D: Swift detection of a short hard burst
  65. GRB 191031C: Fermi GBM Final Real-time Localization
  66. GRB 191029A: Swift-BAT refined analysis
  67. GRB 191031C: Prompt enhanced Swift-XRT position
  68. GRB 191031C: Swift detection of a burst
  69. GRB 191031C: Fermi GBM Final Real-time Localization
  70. GRB 191025B: AstroSat CZTI detection
  71. Fermi trigger No 594175000: Global MASTER-Net observations report
  72. GRB 191031B: Fermi GBM Final Real-time Localization
  73. GRB 191031A: COATLI Optical Observations
  74. GRB 191031A: Fermi GBM Final Real-time Localization
  75. GRB 191031A: Swift detection of a burst
  76. Konus-Wind observation of GRB 191027A
  77. GRB 191029A: CORRECTED Swift-XRT refined analysis
  78. GRB 191019A: Zadko Telescope optical observations
  79. GRB 191029A: Swift/UVOT Upper Limits
  80. Correction to GCN 26079 regarding GRB 191027A
  81. GRB 191029A: Enhanced Swift-XRT position
  82. GRB 191029A: Swift-XRT refined Analysis
  83. GRB 191028B: MASTER optical observation
  84. GRB 191029A: BOOTES-4/MET optical limit
  85. GRB 191029A: iTelescope optical upper limits
  86. GRB 191029A: Swift-XRT observations
  87. Konus-Wind observation of GRB 191025B
  88. GRB 191029A: Swift detection of a burst
  89. IPN triangulation of GRB 191027A
  90. IPN triangulation of GRB 191025B (short)
  91. GRB 191028B: BALROG localization (Fermi Trigger 593964489 / GRB 191028589)
  92. GRB 191028B: Fermi GBM Final Real-time Localization
  93. Fermi GBM trigger 593931926/191028212 is not a GRB
  94. GRB 191028A: Fermi GBM Final Real-time Localization
  95. GRB 191025B: Insight-HXMT/HE detection
  96. Swift/BAT Trigger 931384 is not a GRB ( 191025A )
  97. GRB 191027A: BALROG localization (Fermi Trigger 593882352 / GRB 191027638)
  98. GRB 191027A: Fermi GBM Final Real-time Localization
  99. GRB 191026B: AstroSat CZTI detection
  100. GRB 191026A: Fermi GBM Final Real-time Localization

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