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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"
  1. GRB 050721A: Swift-BAT refined analysis
  2. Correction to GCN Circ 3474 on GRB050525A
  3. GRB 050721A: Early Swift XRT analysis results
  4. GRB050721A: optical decay
  5. GRB 050721: optical afterglow confirmed
  6. Swift BAT Trigger 146986 is SWIFT J1753.5-0127
  7. GRB 050721a: Optical Observations
  8. GRB050721A: Swift-BAT detection of a weak burst
  9. GRB 050709: Refined Spectral and Temporal Properties
  10. GRB 050717: PROMPT RcIc Observations
  11. GRB050714b: Radio Observation
  12. GRB050712: Radio Observations
  13. GRB 050714a: Refined XRT analysis and afterglow confirmation
  14. GRB050713a: Radio Observation
  15. Swift-BAT trigger 146731 is not a real GRB
  16. GRB 050712, Tautenburg optical afterglow observations
  17. Swift-BAT detection of a possible GRB
  18. GRB 050714B: VLT R-band observations
  19. GRB 050717: Additional LCO observations
  20. GRB050717
  21. GRB 050716; J-band observations
  22. Konus-Wind observation of GRB 050717
  23. GRB 050717: LCO near-IR observations
  24. Swift/UVOT Observations of GRB 050717
  25. GRB 050717: Swift-BAT refined analysis
  26. GRB 050717: Refined XRT analysis.
  27. GRB050712: optical limits
  28. GRB050717: Swift XRT position
  29. Swift detection of GRB 050717
  30. GRB 050716 - UKIRT identification of candidate afterglow
  31. Swift UVOT Observations of GRB 050716
  32. GRB 050716: Refined XRT analysis.
  33. GRB050716: Refined analysis of the Swift-BAT burst
  34. GRB 050716: Lulin B and R band optical observations
  35. GRB050716, optical observation
  36. GRB 050716: Optical Observations
  37. GRB050716: Faulkes North Telescope observation
  38. GRB050716: Correction to sign in XRT coordinate
  39. Swift/BAT detection of GRB 050716
  40. GRB050715: Refined analysis of the Swift-BAT burst
  41. GRB 050715: Swift-BAT detection
  42. Swift UVOT Observations of GRB 050714B
  43. Konus-Wind observation of GRB 050713A
  44. GRB 050714B: refined XRT analysis
  45. GRB 050713b: RTT150 optical observations
  46. GRB 050714B: candidate afterglow does not fade
  47. GRB050714B: Refined analysis of the Swift-BAT burst
  48. GRB 050714B: optical afterglow
  49. Swift detection of a long transient (GRB 050714B?)
  50. GRB 050709: optical afterglow candidate
  51. GRB 050714, R-band candidate
  52. GRB 050714: Swift XRT afterglow position
  53. GRB 050714, optical observations
  54. GRB 050714A: ROTSE-III Optical Limits
  55. GRB 050714 - A long GRB detected with INTEGRAL
  56. GRB 050713A: XRT refined analysis
  57. GRB 050709: Spectroscopy
  58. GRB 050713A: RAPTOR detection of early optical emission
  59. GRB050713B :Swift/UVOT observations
  60. GRB050713b: XRT refined analysis
  61. GRB050712: TNG R-band observations
  62. GRB 050713B: Swift-BAT Refined Analysis
  63. Swift-BAT Trigger 145729 is not a GRB
  64. GRB 050713A: Swift/UVOT observation
  65. GRB 050713A : Swift-BAT Refined Analysis
  66. GRB050712: Swift UVOT Observation of Afterglow Emission
  67. GRB 050713A : Lulin R-band observation
  68. GRB 050713A XMM-Newton observation
  69. GRB 050713b : Lulin R-band observations
  70. GRB050713B: Faulkes North Telescope observation
  71. RBO RI observations of GRB 050713A
  72. GRB 050713B
  73. GRB050709 : Chandra source optical counterpart
  74. GRB050713: Liverpool Telescope prompt observations
  75. GRB 050712, optical observations
  76. GRB 050713 : Planned XMM-Newton observation
  77. GRB050709: Candidate X-ray Afterglow from Chandra
  78. GRB 050713, R-band observations at NOT
  79. GRB 050713: ARC NIR Detections and Identification of Fading
  80. GRB050713: possible I-band afterglow
  81. GRB 050713: Swift detection of Bright Burst
  82. GRB 050713A: ROTSE-III Optical Limits
  83. GRB050712: XRT refined analysis
  84. GRB050709: Radio Observations
  85. GRB 050709: Swift UVOT and XRT observations
  86. GRB 050712: Swift-BAT Refined Analysis
  87. GRB050712: UVOT candidate optical counterpart
  88. GRB 050712: Swift XRT afterglow position
  89. GRB 050712: Swift detection of a weak burst
  90. GRB 050709: LCO40 Observations
  91. GRB050709, optical observations
  92. GRB050709: A Possible Short-Hard GRB Localized by HETE
  93. PROMPT Rc Observations of GRB 050709
  94. GRB 050525a: PROMPT VRcIc Detections
  95. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  96. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  97. GRB 050626 optical observations
  98. GRB 050626: Swift XRT observations
  99. GRB 050701
  100. GRB 050701, optical observations

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