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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"

42319 results found.

  1. Swift GRB 260127A: Global MASTER-Net observations report
  2. GRB 260127A: LCO optical afterglow discovery
  3. GRB 260127A: Swift detection of a burst
  4. GRB 260127A: Fermi GBM Final Real-time Localization
  5. GRB 260125A: Swift-XRT observations
  6. EP260126a: EP-FXT follow-up observation
  7. EP260126a: Optical upper limit with Kinder observations
  8. EP260126a: Liverpool Telescope optical upper limits
  9. EP260126a: Further NOT optical upper limits
  10. EP260126a: COLIBRÍ optical upper limits
  11. EP260126a: NOT optical observations
  12. EP260126a: Einstein Probe detection of a fast X-ray transient
  13. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  14. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  15. Konus-Wind detection of GRB 260120B
  16. GRB 251222A: SVOM/ECLAIRs refined analysis
  17. GRB 260125A: Swift ToO observations
  18. GRB 260125A: GOTO candidate optical counterpart
  19. Fermi GRB 260125B: Global MASTER-Net observations report
  20. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB 260125B: Fermi GBM Final Real-time Localization
  22. GRB 260125A: Fermi GBM Final Real-time Localization
  23. GRB 260114A: SVOM/VT optical upper limits
  24. GRB 260120A: AstroSat CZTI detection
  25. GRB 260122B: Swift-BAT refined analysis
  26. GRB 260120B: SVOM/GRM observation
  27. GRB 260120A: GECAM-B observation
  28. GRB 260120B: AstroSat CZTI detection
  29. GRB 260114A: Insight-HXMT/HE detection
  30. GRB 260122B: Swift detection of a burst
  31. Swift GRB260122.97: Global MASTER-Net observations report
  32. EP260119a: Assy AZT-20 optical observations
  33. EP260119a: Mondy and SAO RAS optical upper limits
  34. GRB 260122A: Fermi GBM Final Real-time Localization
  35. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  36. EP260119a: Xinglong optical upper limit
  37. The EP-WXT trigger 01709251871 is likely a flaring star
  38. Fermi GRB 260120C: Global MASTER-Net observations report
  39. GRB 260120B: Swift-BAT refined analysis
  40. GRB 260120B: Swift-XRT refined Analysis
  41. EP260116a: COLIBRÍ further observations
  42. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  43. GRB 260120B: Fermi GBM Observation
  44. EP260105a: GTC/HiPERCAM optical observations
  45. GRB 260120B: Swift/UVOT Detection
  46. GRB 260120B: COLIBRÍ optical upper limits
  47. SVOM GRB260121.06: Global MASTER-Net observations report
  48. GRB 260120B: Enhanced Swift-XRT position
  49. GRB 260120B: SVOM/C-GFT optical counterpart detection
  50. GRB 260120C: Fermi GBM Final Real-time Localization
  51. GRB 260101A: 239Alferov CubeSat detection
  52. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  53. GRB 260120B: Swift detection of a burst
  54. Swift GRB260120B: Global MASTER-Net observations report
  55. GRB 260120B: Fermi GBM Final Real-time Localization
  56. EP260119A: Mondy I-Band Observations
  57. Fermi trigger No 790601190: Global MASTER-Net observations report
  58. Fermi trigger No 790570272: Global MASTER-Net observations report
  59. GRB 260114A: Swift/UVOT Upper Limits
  60. EP260119a: Liverpool Telescope optical follow-up observations
  61. GRB 251202A: further radio observations with the VLA
  62. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  63. EP260119a: KAIT optical observations
  64. GRB 260120A: Fermi GBM Final Real-time Localization
  65. EP260119a: SVOM/VT optical observation
  66. EP260119a: update of EP-FXT follow-up observation
  67. EP260119a: NOT optical observations
  68. EP260119a: SAO RAS optical observations
  69. SVOM GRB260119.92: Global MASTER-Net observations report
  70. SVOM GRB260119.92: Global MASTER-Net observations report
  71. SVOM GRB260119.90: Global MASTER-Net observations report
  72. EP260116a: COLIBRÍ detection of a fading optical source
  73. GRB 251208D: SVOM/ECLAIRs refined analysis
  74. GRB 251208D: SVOM/ECLAIRs refined analysis
  75. GRB 260117A: Swift-XRT afterglow detection
  76. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  77. EP260119a: Global MASTER-Net observations report
  78. GRB 260115A: AstroSat CZTI detection
  79. EP260119a: LCO optical observations
  80. GRB 260117A: ZTSh optical upper limit
  81. EP260119a: COLIBRÍ optical counterpart candidate
  82. EP260119a: preliminary result from the EP-FXT observation
  83. GRB 260110A: SVOM detection of a burst through offline search
  84. EP260119a: EP-WXT detection of a fast X-ray transient
  85. Swift GRB260118.48: Global MASTER-Net observations report
  86. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  87. SVOM GRB260117.82: Global MASTER-Net observations report
  88. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  89. Swift trigger on the HMXB 1A 1118-61
  90. GRB 260117A: SVOM/VT optical candidate
  91. GRB 260117A: SVOM/C-GFT upper limit
  92. GRB 260117A: Swift-XRT observations
  93. GRB 260117A: Swift ToO observations
  94. GRB 260117A: SVOM detection of a long faint burst
  95. EP 260116a: COLIBRÍ optical upper limit
  96. Swift triggered on the HMXB 1A 1118-61
  97. GRB 260115A: GECAM-B observation
  98. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  99. EP260116a: Liverpool Telescope upper limits
  100. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A

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