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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"

21458 results found.

  1. GRB 230827B: Swift ToO observations
  2. GRB 230827A: Fermi GBM Observation
  3. GRB 230826A: Swift-BAT refined analysis
  4. Swift Trigger 1188089 is not a GRB
  5. GRB 230827A: VZLUSAT-2 detection
  6. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  7. GRB 230826A: VZLUSAT-2 detection
  8. Subject: GRB230826A: Swift/UVOT upper limits
  9. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  10. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  11. GRB 230826A: GRBAlpha detection
  12. GRB 230826A: Fermi GBM Observation
  13. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  14. GRB 230826A: Enhanced Swift-XRT position
  15. GRB 230826A: Swift-XRT refined Analysis
  16. GRB 230826A: Mondy optical observations
  17. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  18. GRB 230826A: Swift detection of a burst
  19. Swift GRB230826.81: Global MASTER-Net observations report
  20. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  21. GRB 230824A: AKO Photometric Follow-up Observations
  22. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  23. Swift GRB230825.85: Global MASTER-Net observations report
  24. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  25. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  26. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  27. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  28. Swift GRB230825.75: Global MASTER-Net observations report
  29. Swift Trigger 1187199 is not an astrophysical event
  30. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  31. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  32. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  33. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  34. GRB 230824A: AKO Optical Afterglow Candidate
  35. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  36. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  37. GRB 230824A: Swift detection of a burst
  38. Swift GRB230824.58: Global MASTER-Net observations report
  39. Swift GRB230824.10: Global MASTER-Net observations report
  40. Swift Trigger 1186908 is not a GRB
  41. GRB 230822A: Fermi GBM Observation
  42. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  43. GRB 230822A: Swift/BAT-GUANO detection of a burst
  44. GRID detection of GRB 230818A
  45. GRB 230815A: ATCA detection of radio counterpart
  46. Swift GRB230821.64: Global MASTER-Net observations report
  47. GRB 230818A: Swift-BAT refined analysis
  48. Swift Trigger 1186391 is not a GRB
  49. Swift Trigger 1186390 is not a GRB
  50. Konus-Wind detection of GRB 230818A
  51. Swift Trigger 1186386 is not a GRB
  52. Swift triggers 1186294-1186304 are not astrophysical transients
  53. Swift GRB230820.81: Global MASTER-Net observations report
  54. Swift GRB230820.80: Global MASTER-Net observations report
  55. Swift GRB230820.82: Global MASTER-Net observations report
  56. Swift Triggers 1186280 and 1186291 are not GRBs
  57. GRB 230818A: Fermi GBM Observation
  58. GRB 230818A: SAO RAS 6-m telescope spectroscopy
  59. GRB 230818A: AKO Upper Limit
  60. GRB 230818A: AstroSat CZTI detection
  61. GRB 230818A: Leavitt Observatory upper limit
  62. GRB 230818A: Swift-XRT refined Analysis
  63. GRB 230818A: Bassano Bresciano Observatory optical observations
  64. GRB 230818A: KGO RC-25 optical observations
  65. GRB 230818A: Swift/UVOT Detection
  66. GRB 230818A: NOT photometry and spectroscopy
  67. GRB 230818A: Enhanced Swift-XRT position
  68. GRB 230818A: Swift detection of a burst
  69. Swift GRB230818.98: Global MASTER-Net observations report
  70. Swift GRB230818.98: Global MASTER-Net OT detection
  71. GRB 230816A: Swift-BAT refined analysis
  72. GRB 230816A: SVOM/C-GFT optical detection
  73. GRB 230816A: Swift-XRT refined Analysis
  74. GRB 230816A: Osservatorio Astronomico "Nastro Verde" optical observations
  75. GRB 230815A: VLT/HAWK-I near-infrared afterglow detection
  76. GRB 230816A: Enhanced Swift-XRT position
  77. GRB230816A: Possible host and GIT detection of optical counterpart
  78. Swift GRB230816.80: Global MASTER-Net observations report
  79. IPN triangulation of GRB 230815B
  80. GRB 230816A: Nanshan/HMT optical afterglow detection
  81. GRB 230815A: SOAR/Goodman follow-up imaging
  82. Swift GRB230816.67: Global MASTER-Net observations report
  83. GRB 230816A: Swift detection of a burst
  84. GRB 230815A: Swift-BAT refined analysis
  85. GRB230815A: Swift/UVOT upper limits
  86. GRB 230812B: GAD Observatory optical observations (upper limit)
  87. GRB 230815A: Swift-XRT refined Analysis
  88. GRB 230812B: iTelescope optical upper limit
  89. GRB230815A: BOOTES-6/DPRT optical upper limit
  90. GRB 230815A: Fermi GBM detection
  91. Swift GRB 230815A: Global MASTER-Net observations report
  92. GRB 230815A: Enhanced Swift-XRT position
  93. GRB 230815A: Swift detection of a burst
  94. GRB 230812B: Upper limits from a neutrino search with IceCube
  95. GRB 230812B: GIT optical follow-up
  96. GRB 230812B: Faulkes Telescope North optical afterglow follow-up
  97. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  98. GRB 230812B: OASDG optical observations
  99. GRB 230812B: Detected Optical Afterglow Candidate
  100. GRB230812B: AGILE/MCAL detection

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