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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 050717: Swift-BAT refined analysis
  2. GRB 050717: Refined XRT analysis.
  3. GRB050712: optical limits
  4. GRB050717: Swift XRT position
  5. Swift detection of GRB 050717
  6. GRB 050716 - UKIRT identification of candidate afterglow
  7. Swift UVOT Observations of GRB 050716
  8. GRB 050716: Refined XRT analysis.
  9. GRB050716: Refined analysis of the Swift-BAT burst
  10. GRB 050716: Lulin B and R band optical observations
  11. GRB050716, optical observation
  12. GRB 050716: Optical Observations
  13. GRB050716: Faulkes North Telescope observation
  14. GRB050716: Correction to sign in XRT coordinate
  15. Swift/BAT detection of GRB 050716
  16. GRB050715: Refined analysis of the Swift-BAT burst
  17. GRB 050715: Swift-BAT detection
  18. Swift UVOT Observations of GRB 050714B
  19. Konus-Wind observation of GRB 050713A
  20. GRB 050714B: refined XRT analysis
  21. GRB 050713b: RTT150 optical observations
  22. GRB 050714B: candidate afterglow does not fade
  23. GRB050714B: Refined analysis of the Swift-BAT burst
  24. GRB 050714B: optical afterglow
  25. Swift detection of a long transient (GRB 050714B?)
  26. GRB 050709: optical afterglow candidate
  27. GRB 050714, R-band candidate
  28. GRB 050714: Swift XRT afterglow position
  29. GRB 050714, optical observations
  30. GRB 050714A: ROTSE-III Optical Limits
  31. GRB 050714 - A long GRB detected with INTEGRAL
  32. GRB 050713A: XRT refined analysis
  33. GRB 050709: Spectroscopy
  34. GRB 050713A: RAPTOR detection of early optical emission
  35. GRB050713B :Swift/UVOT observations
  36. GRB050713b: XRT refined analysis
  37. GRB050712: TNG R-band observations
  38. GRB 050713B: Swift-BAT Refined Analysis
  39. Swift-BAT Trigger 145729 is not a GRB
  40. GRB 050713A: Swift/UVOT observation
  41. GRB 050713A : Swift-BAT Refined Analysis
  42. GRB050712: Swift UVOT Observation of Afterglow Emission
  43. GRB 050713A : Lulin R-band observation
  44. GRB 050713A XMM-Newton observation
  45. GRB 050713b : Lulin R-band observations
  46. GRB050713B: Faulkes North Telescope observation
  47. RBO RI observations of GRB 050713A
  48. GRB 050713B
  49. GRB050709 : Chandra source optical counterpart
  50. GRB050713: Liverpool Telescope prompt observations
  51. GRB 050712, optical observations
  52. GRB 050713 : Planned XMM-Newton observation
  53. GRB050709: Candidate X-ray Afterglow from Chandra
  54. GRB 050713, R-band observations at NOT
  55. GRB 050713: ARC NIR Detections and Identification of Fading
  56. GRB050713: possible I-band afterglow
  57. GRB 050713: Swift detection of Bright Burst
  58. GRB 050713A: ROTSE-III Optical Limits
  59. GRB050712: XRT refined analysis
  60. GRB050709: Radio Observations
  61. GRB 050709: Swift UVOT and XRT observations
  62. GRB 050712: Swift-BAT Refined Analysis
  63. GRB050712: UVOT candidate optical counterpart
  64. GRB 050712: Swift XRT afterglow position
  65. GRB 050712: Swift detection of a weak burst
  66. GRB 050709: LCO40 Observations
  67. GRB050709, optical observations
  68. GRB050709: A Possible Short-Hard GRB Localized by HETE
  69. PROMPT Rc Observations of GRB 050709
  70. GRB 050525a: PROMPT VRcIc Detections
  71. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  72. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  73. GRB 050626 optical observations
  74. GRB 050626: Swift XRT observations
  75. GRB 050701
  76. GRB 050701, optical observations
  77. GRB 050408: ARC 3.5-meter NIR Observations
  78. GRB 050701: Refined XRT analysis
  79. Swift UVOT observations of GRB 050701
  80. GRB050701: Swift-BAT Refined analysis
  81. GRB 050701: Swift XRT afterglow position
  82. Swift trigger 143708 is really GRB 050701
  83. GRB 050607, radio observations
  84. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  85. GRB 050626 - Correction to GCN 3552
  86. GRB 050626 - a long GRB detected with INTEGRAL
  87. GRB 050525A: Swift Late-Time Decay Rate
  88. GRB050525a: HST Observations
  89. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  90. H3804: A Possible New XRB Detected by HETE
  91. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  92. XRF 050509c: Optical monitoring
  93. Konus-Wind observation of an intermediate burst from SGR 1806-20
  94. IBAS Alert #2512 is NOT a GRB
  95. XRF050509c: Radio Detection
  96. GRB 050416(a): Host Galaxy Redshift Determination
  97. GRB 050607: MDM Observation
  98. GRB 050607 optical decay
  99. GRB 050607: RTT150 optical observations
  100. GRB050607: refined analysis of prompt REM observations

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