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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"

26559 results found.

  1. GRB 260127A: Swift-BAT refined analysis
  2. GRB 260128B: SVOM detection of a burst through offline search
  3. IPN triangulation of GRB 260127B (short)
  4. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  5. EP260128a: NOT optical counterpart candidate
  6. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  7. EP260126a: SVOM/VT optical upperlimit
  8. EP260128a: Einstein Probe detection of an X-ray transient
  9. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  10. GRB 260127A: Fermi GBM Observation
  11. GRB 260127A: COLIBRÍ optical observations
  12. GRB 260127A: NOT optical observations
  13. EP260126a: Seimei/TriCCS optical upper limit
  14. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  15. GRB 260127B: GOTO candidate optical counterpart
  16. GRB 260127A: SVOM/C-GFT optical observations
  17. GRB 260127A: Enhanced Swift-XRT position
  18. GRB 260127A: Prompt enhanced Swift-XRT position
  19. GRB 260127A: LCO optical afterglow discovery
  20. GRB 260127A: Swift detection of a burst
  21. EP260126a: EP-FXT follow-up observation
  22. EP260126a: Optical upper limit with Kinder observations
  23. EP260126a: COLIBRÍ optical upper limits
  24. EP260126a: Einstein Probe detection of a fast X-ray transient
  25. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  26. Konus-Wind detection of GRB 260120B
  27. GRB 251222A: SVOM/ECLAIRs refined analysis
  28. GRB 260125A: GOTO candidate optical counterpart
  29. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 260114A: SVOM/VT optical upper limits
  31. GRB 260120A: AstroSat CZTI detection
  32. GRB 260122B: Swift-BAT refined analysis
  33. GRB 260120B: SVOM/GRM observation
  34. GRB 260120A: GECAM-B observation
  35. GRB 260120B: AstroSat CZTI detection
  36. GRB 260114A: Insight-HXMT/HE detection
  37. GRB 260122B: Swift detection of a burst
  38. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  39. EP260119a: Xinglong optical upper limit
  40. GRB 260120B: Swift-BAT 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 260101A: 239Alferov CubeSat detection
  51. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  52. GRB 260120B: Swift detection of a burst
  53. EP260119A: Mondy I-Band Observations
  54. EP260119a: Liverpool Telescope optical follow-up observations
  55. GRB 251202A: further radio observations with the VLA
  56. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  57. EP260119a: SVOM/VT optical observation
  58. EP260119a: update of EP-FXT follow-up observation
  59. SVOM GRB260119.92: Global MASTER-Net observations report
  60. SVOM GRB260119.92: Global MASTER-Net observations report
  61. SVOM GRB260119.90: Global MASTER-Net observations report
  62. EP260116a: COLIBRÍ detection of a fading optical source
  63. GRB 251208D: SVOM/ECLAIRs refined analysis
  64. GRB 251208D: SVOM/ECLAIRs refined analysis
  65. GRB 260117A: Swift-XRT afterglow detection
  66. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  67. GRB 260115A: AstroSat CZTI detection
  68. EP260119a: LCO optical observations
  69. GRB 260117A: ZTSh optical upper limit
  70. EP260119a: COLIBRÍ optical counterpart candidate
  71. EP260119a: preliminary result from the EP-FXT observation
  72. GRB 260110A: SVOM detection of a burst through offline search
  73. EP260119a: EP-WXT detection of a fast X-ray transient
  74. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  75. SVOM GRB260117.82: Global MASTER-Net observations report
  76. Swift trigger on the HMXB 1A 1118-61
  77. GRB 260117A: SVOM/VT optical candidate
  78. GRB 260117A: SVOM/C-GFT upper limit
  79. GRB 260117A: Swift-XRT observations
  80. GRB 260117A: Swift ToO observations
  81. GRB 260117A: SVOM detection of a long faint burst
  82. EP 260116a: COLIBRÍ optical upper limit
  83. Swift triggered on the HMXB 1A 1118-61
  84. GRB 260115A: GECAM-B observation
  85. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  86. EP260116A: 1.3m DFOT optical upper limit
  87. GRB 260114A: VLT/MUSE spectroscopic observations
  88. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  89. EP260116a: Xinglong optical upper limit
  90. EP260116a: Einstein Probe detection of an X-ray transient
  91. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  92. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB260114A: STEP/T80S optical limits
  94. GRB 251222A: radio detection with the VLA
  95. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  96. Konus-Wind detection of GRB 260114A
  97. GRB 260114A: 6 GHz VLA observations
  98. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  99. GRB 260114A : MITSuME Akeno optical upper limits
  100. GRB 260114A: COLIBRÍ optical upper limits

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