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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"

42429 results found.

  1. EP260126a: Seimei/TriCCS optical upper limit
  2. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  3. GRB 260127A: Swift-XRT refined Analysis
  4. GRB 260127B: GOTO candidate optical counterpart
  5. GRB 260127A: SVOM/C-GFT optical observations
  6. The EP-WXT trigger 01709253145 is likely a flaring star
  7. GRB 260127A: Enhanced Swift-XRT position
  8. Fermi GRB 260127B: Global MASTER-Net observations report
  9. GRB 260127B: Fermi GBM Final Real-time Localization
  10. GRB 260127A: Prompt enhanced Swift-XRT position
  11. Swift GRB 260127A: Global MASTER-Net observations report
  12. GRB 260127A: LCO optical afterglow discovery
  13. GRB 260127A: Swift detection of a burst
  14. GRB 260127A: Fermi GBM Final Real-time Localization
  15. GRB 260125A: Swift-XRT observations
  16. EP260126a: EP-FXT follow-up observation
  17. EP260126a: Optical upper limit with Kinder observations
  18. EP260126a: Liverpool Telescope optical upper limits
  19. EP260126a: Further NOT optical upper limits
  20. EP260126a: COLIBRÍ optical upper limits
  21. EP260126a: NOT optical observations
  22. EP260126a: Einstein Probe detection of a fast X-ray transient
  23. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  24. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  25. Konus-Wind detection of GRB 260120B
  26. GRB 251222A: SVOM/ECLAIRs refined analysis
  27. GRB 260125A: Swift ToO observations
  28. GRB 260125A: GOTO candidate optical counterpart
  29. Fermi GRB 260125B: Global MASTER-Net observations report
  30. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  31. GRB 260125B: Fermi GBM Final Real-time Localization
  32. GRB 260125A: Fermi GBM Final Real-time Localization
  33. GRB 260114A: SVOM/VT optical upper limits
  34. GRB 260120A: AstroSat CZTI detection
  35. GRB 260122B: Swift-BAT refined analysis
  36. GRB 260120B: SVOM/GRM observation
  37. GRB 260120A: GECAM-B observation
  38. GRB 260120B: AstroSat CZTI detection
  39. GRB 260114A: Insight-HXMT/HE detection
  40. GRB 260122B: Swift detection of a burst
  41. Swift GRB260122.97: Global MASTER-Net observations report
  42. EP260119a: Assy AZT-20 optical observations
  43. EP260119a: Mondy and SAO RAS optical upper limits
  44. GRB 260122A: Fermi GBM Final Real-time Localization
  45. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  46. EP260119a: Xinglong optical upper limit
  47. The EP-WXT trigger 01709251871 is likely a flaring star
  48. Fermi GRB 260120C: Global MASTER-Net observations report
  49. GRB 260120B: Swift-BAT refined analysis
  50. GRB 260120B: Swift-XRT refined Analysis
  51. EP260116a: COLIBRÍ further observations
  52. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  53. GRB 260120B: Fermi GBM Observation
  54. EP260105a: GTC/HiPERCAM optical observations
  55. GRB 260120B: Swift/UVOT Detection
  56. GRB 260120B: COLIBRÍ optical upper limits
  57. SVOM GRB260121.06: Global MASTER-Net observations report
  58. GRB 260120B: Enhanced Swift-XRT position
  59. GRB 260120B: SVOM/C-GFT optical counterpart detection
  60. GRB 260120C: Fermi GBM Final Real-time Localization
  61. GRB 260101A: 239Alferov CubeSat detection
  62. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  63. GRB 260120B: Swift detection of a burst
  64. Swift GRB260120B: Global MASTER-Net observations report
  65. GRB 260120B: Fermi GBM Final Real-time Localization
  66. EP260119A: Mondy I-Band Observations
  67. Fermi trigger No 790601190: Global MASTER-Net observations report
  68. Fermi trigger No 790570272: Global MASTER-Net observations report
  69. GRB 260114A: Swift/UVOT Upper Limits
  70. EP260119a: Liverpool Telescope optical follow-up observations
  71. GRB 251202A: further radio observations with the VLA
  72. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  73. EP260119a: KAIT optical observations
  74. GRB 260120A: Fermi GBM Final Real-time Localization
  75. EP260119a: SVOM/VT optical observation
  76. EP260119a: update of EP-FXT follow-up observation
  77. EP260119a: NOT optical observations
  78. EP260119a: SAO RAS optical observations
  79. SVOM GRB260119.92: Global MASTER-Net observations report
  80. SVOM GRB260119.92: Global MASTER-Net observations report
  81. SVOM GRB260119.90: Global MASTER-Net observations report
  82. EP260116a: COLIBRÍ detection of a fading optical source
  83. GRB 251208D: SVOM/ECLAIRs refined analysis
  84. GRB 251208D: SVOM/ECLAIRs refined analysis
  85. GRB 260117A: Swift-XRT afterglow detection
  86. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  87. EP260119a: Global MASTER-Net observations report
  88. GRB 260115A: AstroSat CZTI detection
  89. EP260119a: LCO optical observations
  90. GRB 260117A: ZTSh optical upper limit
  91. EP260119a: COLIBRÍ optical counterpart candidate
  92. EP260119a: preliminary result from the EP-FXT observation
  93. GRB 260110A: SVOM detection of a burst through offline search
  94. EP260119a: EP-WXT detection of a fast X-ray transient
  95. Swift GRB260118.48: Global MASTER-Net observations report
  96. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  97. SVOM GRB260117.82: Global MASTER-Net observations report
  98. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  99. Swift trigger on the HMXB 1A 1118-61
  100. GRB 260117A: SVOM/VT optical candidate

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