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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"

27784 results found.

  1. EP260126a: Liverpool Telescope optical upper limits
  2. EP260126a: Further NOT optical upper limits
  3. EP260126a: Einstein Probe detection of a fast X-ray transient
  4. Konus-Wind detection of GRB 260120B
  5. GRB 260125A: Swift ToO observations
  6. GRB 260125A: GOTO candidate optical counterpart
  7. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB 260125B: Fermi GBM Final Real-time Localization
  9. GRB 260125A: Fermi GBM Final Real-time Localization
  10. GRB 260114A: SVOM/VT optical upper limits
  11. GRB 260120A: AstroSat CZTI detection
  12. GRB 260122B: Swift-BAT refined analysis
  13. GRB 260120B: SVOM/GRM observation
  14. GRB 260120B: AstroSat CZTI detection
  15. GRB 260114A: Insight-HXMT/HE detection
  16. GRB 260122B: Swift detection of a burst
  17. Swift GRB260122.97: Global MASTER-Net observations report
  18. GRB 260122A: Fermi GBM Final Real-time Localization
  19. EP260119a: Xinglong optical upper limit
  20. GRB 260120B: Swift-BAT refined analysis
  21. GRB 260120B: Swift-XRT refined Analysis
  22. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  23. GRB 260120B: Fermi GBM Observation
  24. EP260105a: GTC/HiPERCAM optical observations
  25. GRB 260120B: Swift/UVOT Detection
  26. GRB 260120B: COLIBRÍ optical upper limits
  27. GRB 260120B: Enhanced Swift-XRT position
  28. GRB 260120B: SVOM/C-GFT optical counterpart detection
  29. GRB 260120C: Fermi GBM Final Real-time Localization
  30. GRB 260101A: 239Alferov CubeSat detection
  31. GRB 260120B: Swift detection of a burst
  32. Swift GRB260120B: Global MASTER-Net observations report
  33. GRB 260120B: Fermi GBM Final Real-time Localization
  34. GRB 260114A: Swift/UVOT Upper Limits
  35. EP260119a: Liverpool Telescope optical follow-up observations
  36. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  37. GRB 260120A: Fermi GBM Final Real-time Localization
  38. EP260119a: update of EP-FXT follow-up observation
  39. EP260116a: COLIBRÍ detection of a fading optical source
  40. GRB 260117A: Swift-XRT afterglow detection
  41. GRB 260115A: AstroSat CZTI detection
  42. GRB 260117A: ZTSh optical upper limit
  43. EP260119a: preliminary result from the EP-FXT observation
  44. GRB 260110A: SVOM detection of a burst through offline search
  45. EP260119a: EP-WXT detection of a fast X-ray transient
  46. Swift GRB260118.48: Global MASTER-Net observations report
  47. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  48. Swift trigger on the HMXB 1A 1118-61
  49. GRB 260117A: SVOM/VT optical candidate
  50. GRB 260117A: SVOM/C-GFT upper limit
  51. GRB 260117A: Swift-XRT observations
  52. GRB 260117A: Swift ToO observations
  53. GRB 260117A: SVOM detection of a long faint burst
  54. Swift triggered on the HMXB 1A 1118-61
  55. EP260116A: 1.3m DFOT optical upper limit
  56. GRB 260114A: VLT/MUSE spectroscopic observations
  57. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  58. EP260116a: Xinglong optical upper limit
  59. EP260116a: Einstein Probe detection of an X-ray transient
  60. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  61. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  62. GRB 260115A: Fermi GBM Final Real-time Localization
  63. GRB260114A: STEP/T80S optical limits
  64. GRB 251222A: radio detection with the VLA
  65. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  66. Konus-Wind detection of GRB 260114A
  67. GRB 260114A: Swift-XRT refined Analysis
  68. GRB 260114A: 6 GHz VLA observations
  69. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  70. GRB 260114A : MITSuME Akeno optical upper limits
  71. GRB 260114A: COLIBRÍ optical upper limits
  72. GRB 260114A: TNG NIR upper limit
  73. GRB 260114A: NOT optical observations
  74. Konus-Wind detection of GRB 251230A / EP251230a
  75. GRB 260114A: SVOM/GRM observation of a short burst
  76. Swift GRB 260114A: Global MASTER-Net observations report
  77. GRB 260114A: GECAM-B observation of a short burst
  78. GRB 260114A: Mondy optical observations
  79. GRB 260114A: Fermi GBM observation
  80. GRB 260114A: GMG Optical Observation
  81. GRB 260114A: Swift detection of a short burst
  82. GRB 260114A: Fermi GBM Final Real-time Localization
  83. Swift GRB260113.43: Global MASTER-Net observations report
  84. EP260110a: TRT optical upper limits
  85. Konus-Wind detection of GRB 260101A
  86. GRB 260111A: Swift-XRT observations
  87. Swift Trigger 1439093: is probably not GRB 260113A
  88. GRB 260111A: COLIBRÍ optical afterglow candidate
  89. GRB 260111A: Fermi GBM Observation
  90. Swift Trigger 1434591 is not a GRB
  91. GRB 260112B: Fermi GBM Final Real-time Localization
  92. GRB 260111A: Swift ToO observations
  93. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  94. GRB 260112A: Fermi GBM Final Real-time Localization
  95. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 260111A: Fermi GBM Final Real-time Localization
  97. Swift trigger 1436759 is not an astrophysical event
  98. EP260110a: BOOTES-5/JGU optical upper limit
  99. EP260110a: Einstein Probe detection of an X-ray transient
  100. GRB 260109C: LCO optical upper limits

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