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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

14326 results found.

  1. Konus-Wind detection of GRB 260131A/B
  2. EP260131a: Xinglong optical upper limit
  3. EP260131a: COLIBRÍ observations of slow optical fading
  4. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  5. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  6. GRB 260131B: MAXI/GSC detection
  7. GRB 260131A: Fermi GBM Final Real-time Localization
  8. EP260131a: Las Cumbres detection of an optical counterpart
  9. GRB 260127B: AstroSat CZTI detection
  10. GRB 260130A: Fermi GBM Detection
  11. EP260131a: Einstein Probe detection of an X-ray transient
  12. GRB 260127B: Fermi GBM Detection
  13. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  14. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  15. GRB 260130A: Fermi GBM Final Real-time Localization
  16. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  17. GRB 260129B: Fermi GBM Final Localization
  18. GRB 260128B: SVOM detection of a burst through offline search
  19. GRB 260129A: Fermi GBM Final Localization
  20. IPN triangulation of GRB 260127B (short)
  21. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  22. EP260128a: NOT optical counterpart candidate
  23. EP260128a: Liverpool Telescope optical observations and possible counterpart
  24. EP260126a: SVOM/VT optical upperlimit
  25. EP260128a: Einstein Probe detection of an X-ray transient
  26. GRB 260127A: NOT optical observations
  27. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  28. GRB 260127A: SVOM/C-GFT optical observations
  29. GRB 260127B: Fermi GBM Final Real-time Localization
  30. GRB 260127A: Swift detection of a burst
  31. GRB 260127A: Fermi GBM Final Real-time Localization
  32. EP260126a: EP-FXT follow-up observation
  33. EP260126a: Liverpool Telescope optical upper limits
  34. EP260126a: Further NOT optical upper limits
  35. EP260126a: NOT optical observations
  36. EP260126a: Einstein Probe detection of a fast X-ray transient
  37. Konus-Wind detection of GRB 260120B
  38. GRB 260125A: GOTO candidate optical counterpart
  39. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260125B: Fermi GBM Final Real-time Localization
  41. GRB 260125A: Fermi GBM Final Real-time Localization
  42. GRB 260114A: SVOM/VT optical upper limits
  43. GRB 260120A: AstroSat CZTI detection
  44. GRB 260120B: AstroSat CZTI detection
  45. GRB 260114A: Insight-HXMT/HE detection
  46. GRB 260122B: Swift detection of a burst
  47. GRB 260122A: Fermi GBM Final Real-time Localization
  48. EP260119a: Xinglong optical upper limit
  49. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  50. EP260105a: GTC/HiPERCAM optical observations
  51. GRB 260120B: Swift/UVOT Detection
  52. GRB 260120B: COLIBRÍ optical upper limits
  53. GRB 260120B: SVOM/C-GFT optical counterpart detection
  54. GRB 260120C: Fermi GBM Final Real-time Localization
  55. GRB 260101A: 239Alferov CubeSat detection
  56. GRB 260120B: Swift detection of a burst
  57. GRB 260120B: Fermi GBM Final Real-time Localization
  58. EP260119a: Liverpool Telescope optical follow-up observations
  59. GRB 251202A: further radio observations with the VLA
  60. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  61. GRB 260120A: Fermi GBM Final Real-time Localization
  62. EP260119a: update of EP-FXT follow-up observation
  63. EP260119a: NOT optical observations
  64. EP260116a: COLIBRÍ detection of a fading optical source
  65. GRB 260117A: Swift-XRT afterglow detection
  66. GRB 260115A: AstroSat CZTI detection
  67. EP260119a: preliminary result from the EP-FXT observation
  68. GRB 260110A: SVOM detection of a burst through offline search
  69. EP260119a: EP-WXT detection of a fast X-ray transient
  70. GRB 260117A: SVOM detection of a long faint burst
  71. EP260116A: 1.3m DFOT optical upper limit
  72. EP260116a: Xinglong optical upper limit
  73. EP260116a: Einstein Probe detection of an X-ray transient
  74. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  75. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 260115A: Fermi GBM Final Real-time Localization
  77. GRB 251222A: radio detection with the VLA
  78. Konus-Wind detection of GRB 260114A
  79. Konus-Wind detection of GRB 251230A / EP251230a
  80. GRB 260114A: Swift detection of a short burst
  81. GRB 260114A: Fermi GBM Final Real-time Localization
  82. EP260110a: TRT optical upper limits
  83. Konus-Wind detection of GRB 260101A
  84. Swift Trigger 1439093: is probably not GRB 260113A
  85. GRB 260111A: COLIBRÍ optical afterglow candidate
  86. GRB 260112B: Fermi GBM Final Real-time Localization
  87. GRB 251230A: Mondy Optical Observations
  88. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  89. GRB 260112A: Fermi GBM Final Real-time Localization
  90. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 260111A: Fermi GBM Final Real-time Localization
  92. EP260110a: BOOTES-5/JGU optical upper limit
  93. EP260110a: Einstein Probe detection of an X-ray transient
  94. GRB 260109C: LCO optical upper limits
  95. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  96. GRB 260109B: Fermi GBM Final Real-time Localization
  97. GRB 260102A: Swift-XRT afterglow detection
  98. GRB 260109A: Fermi GBM Final Real-time Localization
  99. Swift GRB 251230A: Global MASTER-Net OT detection
  100. GRB 260107A: Fermi GBM Final Real-time Localization

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