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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

29100 results found.

  1. GRB 260131A: Fermi GBM Final Real-time Localization
  2. EP260131a: COLIBRÍ optical observations of the counterpart
  3. EP260131a: Las Cumbres detection of an optical counterpart
  4. GRB 260127B: AstroSat CZTI detection
  5. GRB 260130A: Fermi GBM Detection
  6. GRB 260127B: Fermi GBM Detection
  7. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  8. Fermi GRB 260130A: Global MASTER-Net observations report
  9. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  10. GRB 260130A: Fermi GBM Final Real-time Localization
  11. Fermi GRB 260129A: Global MASTER-Net observations report
  12. GRB 260128B: LCO optical upper limits
  13. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  14. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  15. IPN triangulation of GRB 260121A
  16. GRB 260127A: Swift-BAT refined analysis
  17. GRB 260129B: Fermi GBM Final Localization
  18. GRB 260128B: SVOM detection of a burst through offline search
  19. GRB 260129A: Fermi GBM Final Localization
  20. IPN triangulation of GRB 260127B (short)
  21. GRB 260127B: Swift-XRT observations
  22. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  23. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  24. EP260128a: NOT optical counterpart candidate
  25. EP260128a: LCO optical upper limits
  26. EP260126a: SVOM/VT optical upperlimit
  27. EP260128a: Global MASTER-Net observations report
  28. Fermi GRB 260127A: Global MASTER-Net observations report
  29. GRB 260127A: Fermi GBM Observation
  30. GRB 260127A: COLIBRÍ optical observations
  31. GRB 260127A: NOT optical observations
  32. GRB 260127B: Swift ToO observations
  33. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  34. GRB 260127A: Swift-XRT refined Analysis
  35. GRB 260127B: GOTO candidate optical counterpart
  36. GRB 260127A: SVOM/C-GFT optical observations
  37. The EP-WXT trigger 01709253145 is likely a flaring star
  38. Fermi GRB 260127B: Global MASTER-Net observations report
  39. GRB 260127B: Fermi GBM Final Real-time Localization
  40. Swift GRB 260127A: Global MASTER-Net observations report
  41. GRB 260127A: LCO optical afterglow discovery
  42. GRB 260127A: Swift detection of a burst
  43. GRB 260127A: Fermi GBM Final Real-time Localization
  44. GRB 260125A: Swift-XRT observations
  45. EP260126a: Optical upper limit with Kinder observations
  46. EP260126a: Further NOT optical upper limits
  47. EP260126a: COLIBRÍ optical upper limits
  48. EP260126a: NOT optical observations
  49. EP260126a: Einstein Probe detection of a fast X-ray transient
  50. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  51. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  52. Konus-Wind detection of GRB 260120B
  53. GRB 260125A: Swift ToO observations
  54. GRB 260125A: GOTO candidate optical counterpart
  55. Fermi GRB 260125B: Global MASTER-Net observations report
  56. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 260125B: Fermi GBM Final Real-time Localization
  58. GRB 260125A: Fermi GBM Final Real-time Localization
  59. GRB 260114A: SVOM/VT optical upper limits
  60. GRB 260120A: AstroSat CZTI detection
  61. GRB 260122B: Swift-BAT refined analysis
  62. GRB 260120B: SVOM/GRM observation
  63. GRB 260120A: GECAM-B observation
  64. GRB 260120B: AstroSat CZTI detection
  65. GRB 260114A: Insight-HXMT/HE detection
  66. GRB 260122B: Swift detection of a burst
  67. Swift GRB260122.97: Global MASTER-Net observations report
  68. GRB 260122A: Fermi GBM Final Real-time Localization
  69. EP260119a: Xinglong optical upper limit
  70. The EP-WXT trigger 01709251871 is likely a flaring star
  71. Fermi GRB 260120C: Global MASTER-Net observations report
  72. GRB 260120B: Swift-BAT refined analysis
  73. GRB 260120B: Swift-XRT refined Analysis
  74. EP260116a: COLIBRÍ further observations
  75. GRB 260120B: Fermi GBM Observation
  76. EP260105a: GTC/HiPERCAM optical observations
  77. GRB 260120B: Swift/UVOT Detection
  78. GRB 260120B: COLIBRÍ optical upper limits
  79. SVOM GRB260121.06: Global MASTER-Net observations report
  80. GRB 260120B: SVOM/C-GFT optical counterpart detection
  81. GRB 260120C: Fermi GBM Final Real-time Localization
  82. GRB 260101A: 239Alferov CubeSat detection
  83. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  84. GRB 260120B: Swift detection of a burst
  85. Swift GRB260120B: Global MASTER-Net observations report
  86. GRB 260120B: Fermi GBM Final Real-time Localization
  87. Fermi trigger No 790601190: Global MASTER-Net observations report
  88. Fermi trigger No 790570272: Global MASTER-Net observations report
  89. GRB 260114A: Swift/UVOT Upper Limits
  90. EP260119a: Liverpool Telescope optical follow-up observations
  91. GRB 251202A: further radio observations with the VLA
  92. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  93. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  94. GRB 260120A: Fermi GBM Final Real-time Localization
  95. EP260119a: SVOM/VT optical observation
  96. EP260119a: NOT optical observations
  97. SVOM GRB260119.92: Global MASTER-Net observations report
  98. SVOM GRB260119.92: Global MASTER-Net observations report
  99. SVOM GRB260119.90: Global MASTER-Net observations report
  100. EP260116a: COLIBRÍ detection of a fading optical source

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