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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 050713b: RTT150 optical observations
  2. GRB 050714B: candidate afterglow does not fade
  3. GRB050714B: Refined analysis of the Swift-BAT burst
  4. GRB 050714B: optical afterglow
  5. Swift detection of a long transient (GRB 050714B?)
  6. GRB 050709: optical afterglow candidate
  7. GRB 050714, R-band candidate
  8. GRB 050714: Swift XRT afterglow position
  9. GRB 050714, optical observations
  10. GRB 050714A: ROTSE-III Optical Limits
  11. GRB 050714 - A long GRB detected with INTEGRAL
  12. GRB 050713A: XRT refined analysis
  13. GRB 050709: Spectroscopy
  14. GRB 050713A: RAPTOR detection of early optical emission
  15. GRB050713B :Swift/UVOT observations
  16. GRB050713b: XRT refined analysis
  17. GRB050712: TNG R-band observations
  18. GRB 050713B: Swift-BAT Refined Analysis
  19. Swift-BAT Trigger 145729 is not a GRB
  20. GRB 050713A: Swift/UVOT observation
  21. GRB 050713A : Swift-BAT Refined Analysis
  22. GRB050712: Swift UVOT Observation of Afterglow Emission
  23. GRB 050713A : Lulin R-band observation
  24. GRB 050713A XMM-Newton observation
  25. GRB 050713b : Lulin R-band observations
  26. GRB050713B: Faulkes North Telescope observation
  27. RBO RI observations of GRB 050713A
  28. GRB 050713B
  29. GRB050709 : Chandra source optical counterpart
  30. GRB050713: Liverpool Telescope prompt observations
  31. GRB 050712, optical observations
  32. GRB 050713 : Planned XMM-Newton observation
  33. GRB050709: Candidate X-ray Afterglow from Chandra
  34. GRB 050713, R-band observations at NOT
  35. GRB 050713: ARC NIR Detections and Identification of Fading
  36. GRB050713: possible I-band afterglow
  37. GRB 050713: Swift detection of Bright Burst
  38. GRB 050713A: ROTSE-III Optical Limits
  39. GRB050712: XRT refined analysis
  40. GRB050709: Radio Observations
  41. GRB 050709: Swift UVOT and XRT observations
  42. GRB 050712: Swift-BAT Refined Analysis
  43. GRB050712: UVOT candidate optical counterpart
  44. GRB 050712: Swift XRT afterglow position
  45. GRB 050712: Swift detection of a weak burst
  46. GRB 050709: LCO40 Observations
  47. GRB050709, optical observations
  48. GRB050709: A Possible Short-Hard GRB Localized by HETE
  49. PROMPT Rc Observations of GRB 050709
  50. GRB 050525a: PROMPT VRcIc Detections
  51. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  52. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  53. GRB 050626 optical observations
  54. GRB 050626: Swift XRT observations
  55. GRB 050701
  56. GRB 050701, optical observations
  57. GRB 050408: ARC 3.5-meter NIR Observations
  58. GRB 050701: Refined XRT analysis
  59. Swift UVOT observations of GRB 050701
  60. GRB050701: Swift-BAT Refined analysis
  61. GRB 050701: Swift XRT afterglow position
  62. Swift trigger 143708 is really GRB 050701
  63. GRB 050607, radio observations
  64. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  65. GRB 050626 - Correction to GCN 3552
  66. GRB 050626 - a long GRB detected with INTEGRAL
  67. GRB 050525A: Swift Late-Time Decay Rate
  68. GRB050525a: HST Observations
  69. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  70. H3804: A Possible New XRB Detected by HETE
  71. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  72. XRF 050509c: Optical monitoring
  73. Konus-Wind observation of an intermediate burst from SGR 1806-20
  74. IBAS Alert #2512 is NOT a GRB
  75. XRF050509c: Radio Detection
  76. GRB 050416(a): Host Galaxy Redshift Determination
  77. GRB 050607: MDM Observation
  78. GRB 050607 optical decay
  79. GRB 050607: RTT150 optical observations
  80. GRB050607: refined analysis of prompt REM observations
  81. Swift/UVOT observations of GRB050607
  82. GRB 050607 : Lulin R-band observation
  83. GRB 050607: PROMPT VRcIc Observations
  84. GRB 050607: RAPTOR-S Early Optical Limits
  85. GRB050607: KAIT optical limits
  86. GRB 050525a, Mid-Infrared Observations
  87. GRB 050607: Optical decay and spectral slope
  88. GRB 050607: MDM Observations
  89. GRB050607,optical observation
  90. GRB 050607 - XRT refined data analysis
  91. Optical Afterglow of GRB 050607
  92. GRB050607 optical limit by "Pi of the Sky"
  93. GRB050607: Swift Detection of a long GRB
  94. GRB050607: P60 Observations
  95. GRB050607: prompt REM observations
  96. GRB 050603: prediction of t_break
  97. Limits on a SN in the field of GRB 050509b
  98. GRB 050603: Redshift
  99. GRB 050603 - XRT data analysis of the first day
  100. Konus-Wind observation of GRB 050603

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