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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"

27774 results found.

  1. GRB 260120A: AstroSat CZTI detection
  2. GRB 260122B: Swift-BAT refined analysis
  3. GRB 260120B: SVOM/GRM observation
  4. GRB 260120B: AstroSat CZTI detection
  5. GRB 260114A: Insight-HXMT/HE detection
  6. GRB 260122B: Swift detection of a burst
  7. Swift GRB260122.97: Global MASTER-Net observations report
  8. GRB 260122A: Fermi GBM Final Real-time Localization
  9. EP260119a: Xinglong optical upper limit
  10. GRB 260120B: Swift-BAT refined analysis
  11. GRB 260120B: Swift-XRT refined Analysis
  12. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  13. GRB 260120B: Fermi GBM Observation
  14. EP260105a: GTC/HiPERCAM optical observations
  15. GRB 260120B: Swift/UVOT Detection
  16. GRB 260120B: COLIBRÍ optical upper limits
  17. GRB 260120B: Enhanced Swift-XRT position
  18. GRB 260120B: SVOM/C-GFT optical counterpart detection
  19. GRB 260120C: Fermi GBM Final Real-time Localization
  20. GRB 260101A: 239Alferov CubeSat detection
  21. GRB 260120B: Swift detection of a burst
  22. Swift GRB260120B: Global MASTER-Net observations report
  23. GRB 260120B: Fermi GBM Final Real-time Localization
  24. GRB 260114A: Swift/UVOT Upper Limits
  25. EP260119a: Liverpool Telescope optical follow-up observations
  26. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  27. GRB 260120A: Fermi GBM Final Real-time Localization
  28. EP260119a: update of EP-FXT follow-up observation
  29. EP260116a: COLIBRÍ detection of a fading optical source
  30. GRB 260117A: Swift-XRT afterglow detection
  31. GRB 260115A: AstroSat CZTI detection
  32. GRB 260117A: ZTSh optical upper limit
  33. EP260119a: preliminary result from the EP-FXT observation
  34. GRB 260110A: SVOM detection of a burst through offline search
  35. EP260119a: EP-WXT detection of a fast X-ray transient
  36. Swift GRB260118.48: Global MASTER-Net observations report
  37. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  38. Swift trigger on the HMXB 1A 1118-61
  39. GRB 260117A: SVOM/VT optical candidate
  40. GRB 260117A: SVOM/C-GFT upper limit
  41. GRB 260117A: Swift-XRT observations
  42. GRB 260117A: Swift ToO observations
  43. GRB 260117A: SVOM detection of a long faint burst
  44. Swift triggered on the HMXB 1A 1118-61
  45. EP260116A: 1.3m DFOT optical upper limit
  46. GRB 260114A: VLT/MUSE spectroscopic observations
  47. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  48. EP260116a: Xinglong optical upper limit
  49. EP260116a: Einstein Probe detection of an X-ray transient
  50. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  51. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  52. GRB 260115A: Fermi GBM Final Real-time Localization
  53. GRB260114A: STEP/T80S optical limits
  54. GRB 251222A: radio detection with the VLA
  55. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  56. Konus-Wind detection of GRB 260114A
  57. GRB 260114A: Swift-XRT refined Analysis
  58. GRB 260114A: 6 GHz VLA observations
  59. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  60. GRB 260114A : MITSuME Akeno optical upper limits
  61. GRB 260114A: COLIBRÍ optical upper limits
  62. GRB 260114A: TNG NIR upper limit
  63. GRB 260114A: NOT optical observations
  64. Konus-Wind detection of GRB 251230A / EP251230a
  65. GRB 260114A: SVOM/GRM observation of a short burst
  66. Swift GRB 260114A: Global MASTER-Net observations report
  67. GRB 260114A: GECAM-B observation of a short burst
  68. GRB 260114A: Mondy optical observations
  69. GRB 260114A: Fermi GBM observation
  70. GRB 260114A: GMG Optical Observation
  71. GRB 260114A: Swift detection of a short burst
  72. GRB 260114A: Fermi GBM Final Real-time Localization
  73. Swift GRB260113.43: Global MASTER-Net observations report
  74. EP260110a: TRT optical upper limits
  75. Konus-Wind detection of GRB 260101A
  76. GRB 260111A: Swift-XRT observations
  77. Swift Trigger 1439093: is probably not GRB 260113A
  78. GRB 260111A: COLIBRÍ optical afterglow candidate
  79. GRB 260111A: Fermi GBM Observation
  80. Swift Trigger 1434591 is not a GRB
  81. GRB 260112B: Fermi GBM Final Real-time Localization
  82. GRB 260111A: Swift ToO observations
  83. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  84. GRB 260112A: Fermi GBM Final Real-time Localization
  85. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  86. GRB 260111A: Fermi GBM Final Real-time Localization
  87. Swift trigger 1436759 is not an astrophysical event
  88. EP260110a: BOOTES-5/JGU optical upper limit
  89. EP260110a: Einstein Probe detection of an X-ray transient
  90. GRB 260109C: LCO optical upper limits
  91. GRB 260109C: Kilonova-Catcher optical upper limit
  92. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  93. Swift Trigger 1434591: possible GRB 260109C
  94. GRB 260109B: Fermi GBM Final Real-time Localization
  95. GRB 260102A: Swift-XRT afterglow detection
  96. GRB 260109A: Fermi GBM Final Real-time Localization
  97. GRB 260104A: Swift-BAT refined analysis
  98. GRB 260101A: Swift-BAT refined analysis
  99. Swift GRB 251230A: Global MASTER-Net OT detection
  100. GRB 260107A: Fermi GBM Final Real-time Localization

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