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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. GRB050709: Candidate X-ray Afterglow from Chandra
  2. GRB 050713, R-band observations at NOT
  3. GRB 050713: ARC NIR Detections and Identification of Fading
  4. GRB050713: possible I-band afterglow
  5. GRB 050713: Swift detection of Bright Burst
  6. GRB 050713A: ROTSE-III Optical Limits
  7. GRB050712: XRT refined analysis
  8. GRB050709: Radio Observations
  9. GRB 050709: Swift UVOT and XRT observations
  10. GRB 050712: Swift-BAT Refined Analysis
  11. GRB050712: UVOT candidate optical counterpart
  12. GRB 050712: Swift XRT afterglow position
  13. GRB 050712: Swift detection of a weak burst
  14. GRB 050709: LCO40 Observations
  15. GRB050709, optical observations
  16. GRB050709: A Possible Short-Hard GRB Localized by HETE
  17. PROMPT Rc Observations of GRB 050709
  18. GRB 050525a: PROMPT VRcIc Detections
  19. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  20. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  21. GRB 050626 optical observations
  22. GRB 050626: Swift XRT observations
  23. GRB 050701
  24. GRB 050701, optical observations
  25. GRB 050408: ARC 3.5-meter NIR Observations
  26. GRB 050701: Refined XRT analysis
  27. Swift UVOT observations of GRB 050701
  28. GRB050701: Swift-BAT Refined analysis
  29. GRB 050701: Swift XRT afterglow position
  30. Swift trigger 143708 is really GRB 050701
  31. GRB 050607, radio observations
  32. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  33. GRB 050626 - Correction to GCN 3552
  34. GRB 050626 - a long GRB detected with INTEGRAL
  35. GRB 050525A: Swift Late-Time Decay Rate
  36. GRB050525a: HST Observations
  37. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  38. H3804: A Possible New XRB Detected by HETE
  39. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  40. XRF 050509c: Optical monitoring
  41. Konus-Wind observation of an intermediate burst from SGR 1806-20
  42. IBAS Alert #2512 is NOT a GRB
  43. XRF050509c: Radio Detection
  44. GRB 050416(a): Host Galaxy Redshift Determination
  45. GRB 050607: MDM Observation
  46. GRB 050607 optical decay
  47. GRB 050607: RTT150 optical observations
  48. GRB050607: refined analysis of prompt REM observations
  49. Swift/UVOT observations of GRB050607
  50. GRB 050607 : Lulin R-band observation
  51. GRB 050607: PROMPT VRcIc Observations
  52. GRB 050607: RAPTOR-S Early Optical Limits
  53. GRB050607: KAIT optical limits
  54. GRB 050525a, Mid-Infrared Observations
  55. GRB 050607: Optical decay and spectral slope
  56. GRB 050607: MDM Observations
  57. GRB050607,optical observation
  58. GRB 050607 - XRT refined data analysis
  59. Optical Afterglow of GRB 050607
  60. GRB050607 optical limit by "Pi of the Sky"
  61. GRB050607: Swift Detection of a long GRB
  62. GRB050607: P60 Observations
  63. GRB050607: prompt REM observations
  64. GRB 050603: prediction of t_break
  65. Limits on a SN in the field of GRB 050509b
  66. GRB 050603: Redshift
  67. GRB 050603 - XRT data analysis of the first day
  68. Konus-Wind observation of GRB 050603
  69. GRB 050603: Analysis of UVOT data
  70. GRB050603: Fading Afterglow observed by Swift UVOT
  71. GRB050603, submillimetre observations
  72. GRB 050603: Swift XRT Position
  73. GRB050603: Radio Detection
  74. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  75. GRB 050603: Afterglow Identification from LCO
  76. GRB 050603: INTEGRAL shows it is not a short GRB
  77. Swift/BAT Detection of GRB050603
  78. GRB 050408: jet break in the XRT light curve
  79. GRB 050525a, infrared observations
  80. GRB 050525a, SMARTS optical/IR afterglow observations
  81. GRB050528, XRT observations
  82. Correction to GCN Circ 3502 on GRB 050528
  83. GRB050528: updated Liverpool Telescope limits
  84. Swift-BAT GRB 050528: a soft burst
  85. Update on Swift-BAT GRB 050528 (Trigger 130679)
  86. GRB050528: BOOTES optical candidate (retraction)
  87. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  88. GRB050528: BOOTES optical candidate
  89. Possible GRB050528: no candidate from Liverpool Telescope
  90. Swift-BAT detection of possible GRB 050528
  91. GRB050525a: Radio Observations
  92. GRB 050509b: refined XRT/Chandra afterglow position analysis
  93. GRB 050525: RTT150, Optical observations
  94. GRB050525a: optical upper limits
  95. GRB 050525a: SARA Observations
  96. GRB 050525B: Swift-BAT observations
  97. GRB 050525: MITSuME Optical Observation in VRI
  98. GRB 050525a: MDM Observations
  99. GRB050525A,optical observation
  100. GRB 050525 : Lulin optical afterglow observations

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