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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"

19596 results found.

  1. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  2. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  3. Swift GRB230825.75: Global MASTER-Net observations report
  4. Swift Trigger 1187199 is not an astrophysical event
  5. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  6. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  7. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  8. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  9. GRB 230824A: AKO Optical Afterglow Candidate
  10. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  11. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  12. GRB 230824A: Swift detection of a burst
  13. Swift GRB230824.58: Global MASTER-Net observations report
  14. Swift GRB230824.10: Global MASTER-Net observations report
  15. Swift Trigger 1186908 is not a GRB
  16. GRB 230822A: Fermi GBM Observation
  17. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  18. GRB 230822A: Swift/BAT-GUANO detection of a burst
  19. GRID detection of GRB 230818A
  20. GRB 230815A: ATCA detection of radio counterpart
  21. Swift GRB230821.64: Global MASTER-Net observations report
  22. GRB 230818A: Swift-BAT refined analysis
  23. Swift Trigger 1186391 is not a GRB
  24. Swift Trigger 1186390 is not a GRB
  25. Konus-Wind detection of GRB 230818A
  26. Swift Trigger 1186386 is not a GRB
  27. Swift triggers 1186294-1186304 are not astrophysical transients
  28. Swift GRB230820.81: Global MASTER-Net observations report
  29. Swift GRB230820.80: Global MASTER-Net observations report
  30. Swift GRB230820.82: Global MASTER-Net observations report
  31. Swift Triggers 1186280 and 1186291 are not GRBs
  32. GRB 230818A: Fermi GBM Observation
  33. GRB 230818A: SAO RAS 6-m telescope spectroscopy
  34. GRB 230818A: AKO Upper Limit
  35. GRB 230818A: AstroSat CZTI detection
  36. GRB 230818A: Leavitt Observatory upper limit
  37. GRB 230818A: Swift-XRT refined Analysis
  38. GRB 230818A: Bassano Bresciano Observatory optical observations
  39. GRB 230818A: KGO RC-25 optical observations
  40. GRB 230818A: Swift/UVOT Detection
  41. GRB 230818A: NOT photometry and spectroscopy
  42. GRB 230818A: Enhanced Swift-XRT position
  43. GRB 230818A: Swift detection of a burst
  44. Swift GRB230818.98: Global MASTER-Net observations report
  45. Swift GRB230818.98: Global MASTER-Net OT detection
  46. GRB 230816A: Swift-BAT refined analysis
  47. GRB 230816A: SVOM/C-GFT optical detection
  48. GRB 230816A: Swift-XRT refined Analysis
  49. GRB 230816A: Osservatorio Astronomico "Nastro Verde" optical observations
  50. GRB 230816A: Enhanced Swift-XRT position
  51. GRB230816A: Possible host and GIT detection of optical counterpart
  52. Swift GRB230816.80: Global MASTER-Net observations report
  53. IPN triangulation of GRB 230815B
  54. GRB 230816A: Nanshan/HMT optical afterglow detection
  55. GRB 230815A: SOAR/Goodman follow-up imaging
  56. Swift GRB230816.67: Global MASTER-Net observations report
  57. GRB 230816A: Swift detection of a burst
  58. GRB 230815A: Swift-BAT refined analysis
  59. GRB230815A: Swift/UVOT upper limits
  60. GRB 230812B: GAD Observatory optical observations (upper limit)
  61. GRB 230815A: Swift-XRT refined Analysis
  62. GRB 230812B: iTelescope optical upper limit
  63. GRB230815A: BOOTES-6/DPRT optical upper limit
  64. GRB 230815A: Fermi GBM detection
  65. Swift GRB 230815A: Global MASTER-Net observations report
  66. GRB 230815A: Enhanced Swift-XRT position
  67. GRB 230815A: Swift detection of a burst
  68. GRB 230812B: Upper limits from a neutrino search with IceCube
  69. GRB 230812B: GIT optical follow-up
  70. GRB 230812B: Faulkes Telescope North optical afterglow follow-up
  71. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  72. GRB 230812B: OASDG optical observations
  73. GRB 230812B: Detected Optical Afterglow Candidate
  74. GRB230812B: AGILE/MCAL detection
  75. GRB 230812B: Swift-XRT afterglow detection
  76. GRB 230812: Swift/UVOT Detection
  77. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
  78. GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
  79. Fermi GRB 230812B: MASTER optical counterpart
  80. GRB 230812B: KAIT Optical Afterglow Candidate
  81. GRB 230812B: Improved Swift/XRT localization
  82. GRB 230812B: Preliminary Swift/XRT localization
  83. GRB 230812B: Tiled Swift observations
  84. GRB 230808A: Fermi GBM Detection
  85. GRB 230805B: Swift-BAT refined analysis
  86. GRB 230805B: Iota Scorpii Observatory, La Spezia, Italy upper limit
  87. GRB 230805B: AstroSat CZTI detection
  88. GRB 230808A: Swift/BAT-GUANO detection of a burst
  89. GRB 230805B : MITSuME Akeno optical upper limits
  90. LIGO/Virgo/KAGRA S230805x: Upper limits from Swift/BAT-GUANO
  91. GRB 230805B: Fermi GBM observation
  92. GRB 230805B: Enhanced Swift-XRT position
  93. GRB 230805B: Swift/UVOT Upper Limits
  94. GRB 230805B: Bassano Bresciano observatory upper limit
  95. GRB 230805B: BOOTES-6/DPRT optical upper limit and 1.5m OSN detection
  96. GRB 230805B: Swift-XRT refined Analysis
  97. Swift GRB 230805B: Global MASTER-Net observations report
  98. GRB 230805B: Swift detection of a burst
  99. GRB 230802A: Fermi GBM observation
  100. GRB 230802A: Swift-BAT refined analysis

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