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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"

45723 results found.

  1. GRB 260127A: Swift-BAT refined analysis
  2. GRB 260129B: Fermi GBM Final Localization
  3. GRB 260128B: SVOM detection of a burst through offline search
  4. GRB 260129A: Fermi GBM Final Localization
  5. IPN triangulation of GRB 260127B (short)
  6. GRB 260127B: Swift-XRT observations
  7. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  8. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  9. EP260128a: NOT optical counterpart candidate
  10. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  11. EP260128a: Liverpool Telescope optical observations and possible counterpart
  12. EP260128a: LCO optical upper limits
  13. EP260126a: SVOM/VT optical upperlimit
  14. EP260128a: Global MASTER-Net observations report
  15. EP260128a: Einstein Probe detection of an X-ray transient
  16. Fermi GRB 260127A: Global MASTER-Net observations report
  17. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  18. GRB 260127A: Fermi GBM Observation
  19. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 260127A: COLIBRÍ optical observations
  21. GRB 260127A: NOT optical observations
  22. GRB 260127B: Swift ToO observations
  23. EP260126a: Seimei/TriCCS optical upper limit
  24. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  25. GRB 260127A: Swift-XRT refined Analysis
  26. GRB 260127B: GOTO candidate optical counterpart
  27. GRB 260127A: SVOM/C-GFT optical observations
  28. The EP-WXT trigger 01709253145 is likely a flaring star
  29. GRB 260127A: Enhanced Swift-XRT position
  30. Fermi GRB 260127B: Global MASTER-Net observations report
  31. GRB 260127B: Fermi GBM Final Real-time Localization
  32. GRB 260127A: Prompt enhanced Swift-XRT position
  33. Swift GRB 260127A: Global MASTER-Net observations report
  34. GRB 260127A: LCO optical afterglow discovery
  35. GRB 260127A: Swift detection of a burst
  36. GRB 260127A: Fermi GBM Final Real-time Localization
  37. GRB 260125A: Swift-XRT observations
  38. EP260126a: EP-FXT follow-up observation
  39. EP260126a: Optical upper limit with Kinder observations
  40. EP260126a: Liverpool Telescope optical upper limits
  41. EP260126a: Further NOT optical upper limits
  42. EP260126a: COLIBRÍ optical upper limits
  43. EP260126a: NOT optical observations
  44. EP260126a: Einstein Probe detection of a fast X-ray transient
  45. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  46. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  47. Konus-Wind detection of GRB 260120B
  48. GRB 251222A: SVOM/ECLAIRs refined analysis
  49. GRB 260125A: Swift ToO observations
  50. GRB 260125A: GOTO candidate optical counterpart
  51. Fermi GRB 260125B: Global MASTER-Net observations report
  52. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  53. GRB 260125B: Fermi GBM Final Real-time Localization
  54. GRB 260125A: Fermi GBM Final Real-time Localization
  55. GRB 260114A: SVOM/VT optical upper limits
  56. GRB 260120A: AstroSat CZTI detection
  57. GRB 260122B: Swift-BAT refined analysis
  58. GRB 260120B: SVOM/GRM observation
  59. GRB 260120A: GECAM-B observation
  60. GRB 260120B: AstroSat CZTI detection
  61. GRB 260114A: Insight-HXMT/HE detection
  62. GRB 260122B: Swift detection of a burst
  63. Swift GRB260122.97: Global MASTER-Net observations report
  64. EP260119a: Assy AZT-20 optical observations
  65. EP260119a: Mondy and SAO RAS optical upper limits
  66. GRB 260122A: Fermi GBM Final Real-time Localization
  67. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  68. EP260119a: Xinglong optical upper limit
  69. The EP-WXT trigger 01709251871 is likely a flaring star
  70. Fermi GRB 260120C: Global MASTER-Net observations report
  71. GRB 260120B: Swift-BAT refined analysis
  72. GRB 260120B: Swift-XRT refined Analysis
  73. EP260116a: COLIBRÍ further observations
  74. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  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: Enhanced Swift-XRT position
  81. GRB 260120B: SVOM/C-GFT optical counterpart detection
  82. GRB 260120C: Fermi GBM Final Real-time Localization
  83. GRB 260101A: 239Alferov CubeSat detection
  84. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  85. GRB 260120B: Swift detection of a burst
  86. Swift GRB260120B: Global MASTER-Net observations report
  87. GRB 260120B: Fermi GBM Final Real-time Localization
  88. EP260119A: Mondy I-Band Observations
  89. Fermi trigger No 790601190: Global MASTER-Net observations report
  90. Fermi trigger No 790570272: Global MASTER-Net observations report
  91. GRB 260114A: Swift/UVOT Upper Limits
  92. EP260119a: Liverpool Telescope optical follow-up observations
  93. GRB 251202A: further radio observations with the VLA
  94. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  95. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  96. EP260119a: KAIT optical observations
  97. GRB 260120A: Fermi GBM Final Real-time Localization
  98. EP260119a: SVOM/VT optical observation
  99. EP260119a: update of EP-FXT follow-up observation
  100. EP260119a: NOT optical observations

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