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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 050713A: RAPTOR detection of early optical emission
  2. GRB050713B :Swift/UVOT observations
  3. GRB050713b: XRT refined analysis
  4. GRB050712: TNG R-band observations
  5. GRB 050713B: Swift-BAT Refined Analysis
  6. Swift-BAT Trigger 145729 is not a GRB
  7. GRB 050713A: Swift/UVOT observation
  8. GRB 050713A : Swift-BAT Refined Analysis
  9. GRB050712: Swift UVOT Observation of Afterglow Emission
  10. GRB 050713A : Lulin R-band observation
  11. GRB 050713A XMM-Newton observation
  12. GRB 050713b : Lulin R-band observations
  13. GRB050713B: Faulkes North Telescope observation
  14. RBO RI observations of GRB 050713A
  15. GRB 050713B
  16. GRB050709 : Chandra source optical counterpart
  17. GRB050713: Liverpool Telescope prompt observations
  18. GRB 050712, optical observations
  19. GRB 050713 : Planned XMM-Newton observation
  20. GRB050709: Candidate X-ray Afterglow from Chandra
  21. GRB 050713, R-band observations at NOT
  22. GRB 050713: ARC NIR Detections and Identification of Fading
  23. GRB050713: possible I-band afterglow
  24. GRB 050713: Swift detection of Bright Burst
  25. GRB 050713A: ROTSE-III Optical Limits
  26. GRB050712: XRT refined analysis
  27. GRB050709: Radio Observations
  28. GRB 050709: Swift UVOT and XRT observations
  29. GRB 050712: Swift-BAT Refined Analysis
  30. GRB050712: UVOT candidate optical counterpart
  31. GRB 050712: Swift XRT afterglow position
  32. GRB 050712: Swift detection of a weak burst
  33. GRB 050709: LCO40 Observations
  34. GRB050709, optical observations
  35. GRB050709: A Possible Short-Hard GRB Localized by HETE
  36. PROMPT Rc Observations of GRB 050709
  37. GRB 050525a: PROMPT VRcIc Detections
  38. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  39. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  40. GRB 050626 optical observations
  41. GRB 050626: Swift XRT observations
  42. GRB 050701
  43. GRB 050701, optical observations
  44. GRB 050408: ARC 3.5-meter NIR Observations
  45. GRB 050701: Refined XRT analysis
  46. Swift UVOT observations of GRB 050701
  47. GRB050701: Swift-BAT Refined analysis
  48. GRB 050701: Swift XRT afterglow position
  49. Swift trigger 143708 is really GRB 050701
  50. GRB 050607, radio observations
  51. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  52. GRB 050626 - Correction to GCN 3552
  53. GRB 050626 - a long GRB detected with INTEGRAL
  54. GRB 050525A: Swift Late-Time Decay Rate
  55. GRB050525a: HST Observations
  56. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  57. H3804: A Possible New XRB Detected by HETE
  58. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  59. XRF 050509c: Optical monitoring
  60. Konus-Wind observation of an intermediate burst from SGR 1806-20
  61. IBAS Alert #2512 is NOT a GRB
  62. XRF050509c: Radio Detection
  63. GRB 050416(a): Host Galaxy Redshift Determination
  64. GRB 050607: MDM Observation
  65. GRB 050607 optical decay
  66. GRB 050607: RTT150 optical observations
  67. GRB050607: refined analysis of prompt REM observations
  68. Swift/UVOT observations of GRB050607
  69. GRB 050607 : Lulin R-band observation
  70. GRB 050607: PROMPT VRcIc Observations
  71. GRB 050607: RAPTOR-S Early Optical Limits
  72. GRB050607: KAIT optical limits
  73. GRB 050525a, Mid-Infrared Observations
  74. GRB 050607: Optical decay and spectral slope
  75. GRB 050607: MDM Observations
  76. GRB050607,optical observation
  77. GRB 050607 - XRT refined data analysis
  78. Optical Afterglow of GRB 050607
  79. GRB050607 optical limit by "Pi of the Sky"
  80. GRB050607: Swift Detection of a long GRB
  81. GRB050607: P60 Observations
  82. GRB050607: prompt REM observations
  83. GRB 050603: prediction of t_break
  84. Limits on a SN in the field of GRB 050509b
  85. GRB 050603: Redshift
  86. GRB 050603 - XRT data analysis of the first day
  87. Konus-Wind observation of GRB 050603
  88. GRB 050603: Analysis of UVOT data
  89. GRB050603: Fading Afterglow observed by Swift UVOT
  90. GRB050603, submillimetre observations
  91. GRB 050603: Swift XRT Position
  92. GRB050603: Radio Detection
  93. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  94. GRB 050603: Afterglow Identification from LCO
  95. GRB 050603: INTEGRAL shows it is not a short GRB
  96. Swift/BAT Detection of GRB050603
  97. GRB 050408: jet break in the XRT light curve
  98. GRB 050525a, infrared observations
  99. GRB 050525a, SMARTS optical/IR afterglow observations
  100. GRB050528, XRT observations

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