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

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