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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"

21455 results found.

  1. EP240408a: GROND detection of a candidate counterpart
  2. EP240408a: Swift follow-up observation
  3. Swift Trigger 1220736: detection of 4U 1543-62.
  4. Swift satellite resumes pointed science observations
  5. GRB 240318A: Fermi GBM Observation
  6. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  7. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  8. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  9. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  10. GRB 240317B: Swift/BAT-GUANO Angular Error Correction
  11. GRB 240317B: Fermi GBM Observation
  12. Swift satellite in safe mode
  13. GRB 240317B: Swift/BAT-GUANO arcminute localization of a burst
  14. Einstein Probe detected of a fast X-ray transient EP240315a
  15. GRID detection of GRB 240306A
  16. Swift Triggers 1220155, 1220156, 1220157, 1220158, 1220160 and 1220161 were not astrophysical
  17. Swift Triggers 1220093, 1220094, 1220095 and 1220096 are not astrophysical
  18. Swift Triggers 1220090, 1220091 and 1220092 are not astrophysical
  19. GRB240204A: VIRT optical upper limit
  20. Swift triggers 1219917, 1219917 and 1219922 were not astrophysical
  21. Swift Trigger 1219909 and 1219910 are not a astrophysical
  22. Swift Trigger 1219905 is not a GRB
  23. Swift Trigger 1219874 is not astrophysical
  24. Swift GRB240309.61: Global MASTER-Net observations report
  25. Swift Trigger 1219325 is not a GRB
  26. GRB 240306A: Fermi GBM observation
  27. Konus-Wind detection of GRB 231118A
  28. GRB 240306A: AstroSat CZTI detection
  29. GRB 240306A: Swift/BAT-GUANO detection of a burst
  30. GRB 240305A: Fermi GBM observation
  31. Swift GRB240305.18: Global MASTER-Net observations report
  32. Swift GRB240305.16: Global MASTER-Net observations report
  33. GRB 240305A: Swift/BAT-GUANO arcminute localization of a burst
  34. GRB 240218A: Chandra Detection and Jet Break Confirmation
  35. Swift Trigger 1218701: Yes, we triggered on Swift J151857.0-572147 again
  36. Swift Trigger 1218696: Another trigger on Swift J151857.0-572147
  37. Swift Trigger 1218645: Another detection of Swift J151857.0-572147
  38. Swift J151857.0-572147: Swift-BAT refined analysis
  39. GRB 240225B: Swift-XRT afterglow detection
  40. Swift detection of Swift J151857.0-572147
  41. Swift GRB 240303A: Global MASTER-Net observations report
  42. Swift J151857.0-572147: Confirmation of a new galactic transient
  43. GRB 240215A: Swift-XRT afterglow detection
  44. GRB 240303A: Swift detection of a burst
  45. GRB 240225A (short): Glowbug gamma-ray detection
  46. Swift BAT Triggers 1218081 and 1218082 are not astrophysical
  47. GRB 240225B: Swift ToO observations
  48. GRB 240225B: 3.6m DOT observation
  49. Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
  50. Swift Trigger 1217799 is not a GRB
  51. GRB 240218A: CMO SAI NIR upper limit
  52. Swift-BAT triggers 1217733 - 1217736 are not astrophysical events
  53. Swift-BAT triggers 1217729-1217732 are not astrophysical
  54. GRB 240225B: Nanshan/HMT optical afterglow detection
  55. GRB 240225B: Swift-XRT observations
  56. GRB 240225B: GOTO detection of a candidate optical afterglow
  57. GRB 240222A: ATCA radio observations
  58. GRB 240225B: Tiled Swift observations
  59. Transient EPW20240219aa: Xinglong-2.16m optical upper limit
  60. GRB 240225A: Swift/BAT-GUANO detection of a short burst
  61. GRB 240222A: GRBAlpha detection
  62. Swift-BAT triggers 1217218-1217222 are not astrophysical
  63. Transient EPW20240219aa: Mondy optical observations
  64. Insight-HXMT/HE Sub-Threshold Detection of Transient EPW20240219aa
  65. Swift BAT Sub-Threshold Detection of EPW20240219aa
  66. GRB 240222A: GECAM detection of a burst
  67. GRB 240222A: Swift-BAT refined analysis
  68. GRB 240222A: Swift-XRT refined Analysis
  69. Swift-BAT triggers 1216907-1216911 are not astrophysical
  70. GRB 240222A: Fermi GBM Observation
  71. GRB 240222A: Swift/UVOT Upper Limits
  72. Swift GRB 240222A: Global MASTER-Net observations report
  73. Swift Trigger 1216864 is not an astrophysical event
  74. GRB 240222A: REM optical and NIR early-time observations
  75. GRB 240222A: Swift detection of a burst
  76. Swift-BAT triggers 1216751 and 1216753 are not astrophysical events
  77. Swift-BAT triggers 1216743-1216748 are not astrophysical
  78. Swift GRB240221.92: Global MASTER-Net observations report
  79. GRB 240218A: MeerLICHT upper limits
  80. GRB 240215B: Fermi GBM Observation
  81. GRB 240218A: LBT H-band detection
  82. GRB 240218A: Swift-BAT refined analysis
  83. Konus-Wind detection of GRB 240218A
  84. GRB 240218A: Swift-XRT refined Analysis
  85. GRB 240218A: VLT/X-shooter redshift of z = 6.782
  86. GRB 240218A: Fermi GBM Detection
  87. GRB 240215A: Fermi GBM Observation
  88. GRB 240215B: GRBAlpha detection
  89. IPN triangulation of GRB 240209A
  90. GRB 240218A: Enhanced Swift-XRT position
  91. GRB 240218A: REM detection of a NIR afterglow candidate
  92. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  93. GRB240218A: VLT/X-shooter upper limits
  94. GRB 240218A: Swift detection of a burst
  95. Swift GRB240218.08: Global MASTER-Net observations report
  96. GRB 240215B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  97. Swift Triggers 12156887-1215690 are not astrophysical events.
  98. GRB 240215A: Tiled Swift observations
  99. GRB 240215A: Swift/BAT-GUANO localization of a burst
  100. GRB 240128A: Further Swift-XRT observations

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