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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"

45555 results found.

  1. EP260131a: Las Cumbres detection of an optical counterpart
  2. GRB 260127B: AstroSat CZTI detection
  3. GRB 260130A: Fermi GBM Detection
  4. EP260131a: Einstein Probe detection of an X-ray transient
  5. GRB 260127B: Fermi GBM Detection
  6. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  7. Fermi GRB 260130A: Global MASTER-Net observations report
  8. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  9. GRB 260130A: Fermi GBM Final Real-time Localization
  10. Fermi GRB 260129A: Global MASTER-Net observations report
  11. GRB 260128B: LCO optical upper limits
  12. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  13. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  14. IPN triangulation of GRB 260121A
  15. GRB 260127A: Swift-BAT refined analysis
  16. GRB 260129B: Fermi GBM Final Localization
  17. GRB 260128B: SVOM detection of a burst through offline search
  18. GRB 260129A: Fermi GBM Final Localization
  19. IPN triangulation of GRB 260127B (short)
  20. GRB 260127B: Swift-XRT observations
  21. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  22. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  23. EP260128a: NOT optical counterpart candidate
  24. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  25. EP260128a: Liverpool Telescope optical observations and possible counterpart
  26. EP260128a: LCO optical upper limits
  27. EP260126a: SVOM/VT optical upperlimit
  28. EP260128a: Global MASTER-Net observations report
  29. EP260128a: Einstein Probe detection of an X-ray transient
  30. Fermi GRB 260127A: Global MASTER-Net observations report
  31. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  32. GRB 260127A: Fermi GBM Observation
  33. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 260127A: COLIBRÍ optical observations
  35. GRB 260127A: NOT optical observations
  36. GRB 260127B: Swift ToO observations
  37. EP260126a: Seimei/TriCCS optical upper limit
  38. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  39. GRB 260127A: Swift-XRT refined Analysis
  40. GRB 260127B: GOTO candidate optical counterpart
  41. GRB 260127A: SVOM/C-GFT optical observations
  42. The EP-WXT trigger 01709253145 is likely a flaring star
  43. GRB 260127A: Enhanced Swift-XRT position
  44. Fermi GRB 260127B: Global MASTER-Net observations report
  45. GRB 260127B: Fermi GBM Final Real-time Localization
  46. GRB 260127A: Prompt enhanced Swift-XRT position
  47. Swift GRB 260127A: Global MASTER-Net observations report
  48. GRB 260127A: LCO optical afterglow discovery
  49. GRB 260127A: Swift detection of a burst
  50. GRB 260127A: Fermi GBM Final Real-time Localization
  51. GRB 260125A: Swift-XRT observations
  52. EP260126a: EP-FXT follow-up observation
  53. EP260126a: Optical upper limit with Kinder observations
  54. EP260126a: Liverpool Telescope optical upper limits
  55. EP260126a: Further NOT optical upper limits
  56. EP260126a: COLIBRÍ optical upper limits
  57. EP260126a: NOT optical observations
  58. EP260126a: Einstein Probe detection of a fast X-ray transient
  59. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  60. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  61. Konus-Wind detection of GRB 260120B
  62. GRB 251222A: SVOM/ECLAIRs refined analysis
  63. GRB 260125A: Swift ToO observations
  64. GRB 260125A: GOTO candidate optical counterpart
  65. Fermi GRB 260125B: Global MASTER-Net observations report
  66. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 260125B: Fermi GBM Final Real-time Localization
  68. GRB 260125A: Fermi GBM Final Real-time Localization
  69. GRB 260114A: SVOM/VT optical upper limits
  70. GRB 260120A: AstroSat CZTI detection
  71. GRB 260122B: Swift-BAT refined analysis
  72. GRB 260120B: SVOM/GRM observation
  73. GRB 260120A: GECAM-B observation
  74. GRB 260120B: AstroSat CZTI detection
  75. GRB 260114A: Insight-HXMT/HE detection
  76. GRB 260122B: Swift detection of a burst
  77. Swift GRB260122.97: Global MASTER-Net observations report
  78. EP260119a: Assy AZT-20 optical observations
  79. EP260119a: Mondy and SAO RAS optical upper limits
  80. GRB 260122A: Fermi GBM Final Real-time Localization
  81. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  82. EP260119a: Xinglong optical upper limit
  83. The EP-WXT trigger 01709251871 is likely a flaring star
  84. Fermi GRB 260120C: Global MASTER-Net observations report
  85. GRB 260120B: Swift-BAT refined analysis
  86. GRB 260120B: Swift-XRT refined Analysis
  87. EP260116a: COLIBRÍ further observations
  88. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  89. GRB 260120B: Fermi GBM Observation
  90. EP260105a: GTC/HiPERCAM optical observations
  91. GRB 260120B: Swift/UVOT Detection
  92. GRB 260120B: COLIBRÍ optical upper limits
  93. SVOM GRB260121.06: Global MASTER-Net observations report
  94. GRB 260120B: Enhanced Swift-XRT position
  95. GRB 260120B: SVOM/C-GFT optical counterpart detection
  96. GRB 260120C: Fermi GBM Final Real-time Localization
  97. GRB 260101A: 239Alferov CubeSat detection
  98. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  99. GRB 260120B: Swift detection of a burst
  100. Swift GRB260120B: Global MASTER-Net observations report

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