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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. Swift-BAT detection of a possible GRB
  2. GRB 050714B: VLT R-band observations
  3. GRB 050717: Additional LCO observations
  4. GRB050717
  5. GRB 050716; J-band observations
  6. Konus-Wind observation of GRB 050717
  7. GRB 050717: LCO near-IR observations
  8. Swift/UVOT Observations of GRB 050717
  9. GRB 050717: Swift-BAT refined analysis
  10. GRB 050717: Refined XRT analysis.
  11. GRB050712: optical limits
  12. GRB050717: Swift XRT position
  13. Swift detection of GRB 050717
  14. GRB 050716 - UKIRT identification of candidate afterglow
  15. Swift UVOT Observations of GRB 050716
  16. GRB 050716: Refined XRT analysis.
  17. GRB050716: Refined analysis of the Swift-BAT burst
  18. GRB 050716: Lulin B and R band optical observations
  19. GRB050716, optical observation
  20. GRB 050716: Optical Observations
  21. GRB050716: Faulkes North Telescope observation
  22. GRB050716: Correction to sign in XRT coordinate
  23. Swift/BAT detection of GRB 050716
  24. GRB050715: Refined analysis of the Swift-BAT burst
  25. GRB 050715: Swift-BAT detection
  26. Swift UVOT Observations of GRB 050714B
  27. Konus-Wind observation of GRB 050713A
  28. GRB 050714B: refined XRT analysis
  29. GRB 050713b: RTT150 optical observations
  30. GRB 050714B: candidate afterglow does not fade
  31. GRB050714B: Refined analysis of the Swift-BAT burst
  32. GRB 050714B: optical afterglow
  33. Swift detection of a long transient (GRB 050714B?)
  34. GRB 050709: optical afterglow candidate
  35. GRB 050714, R-band candidate
  36. GRB 050714: Swift XRT afterglow position
  37. GRB 050714, optical observations
  38. GRB 050714A: ROTSE-III Optical Limits
  39. GRB 050714 - A long GRB detected with INTEGRAL
  40. GRB 050713A: XRT refined analysis
  41. GRB 050709: Spectroscopy
  42. GRB 050713A: RAPTOR detection of early optical emission
  43. GRB050713B :Swift/UVOT observations
  44. GRB050713b: XRT refined analysis
  45. GRB050712: TNG R-band observations
  46. GRB 050713B: Swift-BAT Refined Analysis
  47. Swift-BAT Trigger 145729 is not a GRB
  48. GRB 050713A: Swift/UVOT observation
  49. GRB 050713A : Swift-BAT Refined Analysis
  50. GRB050712: Swift UVOT Observation of Afterglow Emission
  51. GRB 050713A : Lulin R-band observation
  52. GRB 050713A XMM-Newton observation
  53. GRB 050713b : Lulin R-band observations
  54. GRB050713B: Faulkes North Telescope observation
  55. RBO RI observations of GRB 050713A
  56. GRB 050713B
  57. GRB050709 : Chandra source optical counterpart
  58. GRB050713: Liverpool Telescope prompt observations
  59. GRB 050712, optical observations
  60. GRB 050713 : Planned XMM-Newton observation
  61. GRB050709: Candidate X-ray Afterglow from Chandra
  62. GRB 050713, R-band observations at NOT
  63. GRB 050713: ARC NIR Detections and Identification of Fading
  64. GRB050713: possible I-band afterglow
  65. GRB 050713: Swift detection of Bright Burst
  66. GRB 050713A: ROTSE-III Optical Limits
  67. GRB050712: XRT refined analysis
  68. GRB050709: Radio Observations
  69. GRB 050709: Swift UVOT and XRT observations
  70. GRB 050712: Swift-BAT Refined Analysis
  71. GRB050712: UVOT candidate optical counterpart
  72. GRB 050712: Swift XRT afterglow position
  73. GRB 050712: Swift detection of a weak burst
  74. GRB 050709: LCO40 Observations
  75. GRB050709, optical observations
  76. GRB050709: A Possible Short-Hard GRB Localized by HETE
  77. PROMPT Rc Observations of GRB 050709
  78. GRB 050525a: PROMPT VRcIc Detections
  79. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  80. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  81. GRB 050626 optical observations
  82. GRB 050626: Swift XRT observations
  83. GRB 050701
  84. GRB 050701, optical observations
  85. GRB 050408: ARC 3.5-meter NIR Observations
  86. GRB 050701: Refined XRT analysis
  87. Swift UVOT observations of GRB 050701
  88. GRB050701: Swift-BAT Refined analysis
  89. GRB 050701: Swift XRT afterglow position
  90. Swift trigger 143708 is really GRB 050701
  91. GRB 050607, radio observations
  92. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  93. GRB 050626 - Correction to GCN 3552
  94. GRB 050626 - a long GRB detected with INTEGRAL
  95. GRB 050525A: Swift Late-Time Decay Rate
  96. GRB050525a: HST Observations
  97. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  98. H3804: A Possible New XRB Detected by HETE
  99. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  100. XRF 050509c: Optical monitoring

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