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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 050502b: Swift XRT Position
  2. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  3. GRB050502B: Optical Limits from ANU 1m
  4. Swift Detection of the Bright Burst GRB050502b
  5. GRB 050502: INTEGRAL results
  6. GRB050502: ANU 1m optical Observations
  7. GRB 050502: Confirmed variability of the afterglow candidate +
  8. GRB 050502: PAIRITEL IR Observations
  9. GRB050502 - Correction on the Optical Candidate from the Liverpool
  10. GRB050502 - Optical Candidate from the Liverpool Telescope
  11. GRB 050502 - A long GRB detected with INTEGRAL
  12. GRB 050502: ROTSE-III Detection of Possible Counterpart
  13. Swift-BAT Trigger 115881 is not a real GRB
  14. Swift/BAT possible detection of a weak burst GRB050430
  15. GRB 050401: Rc observation
  16. GRB050416a: Radio Detection
  17. GRB 050422: Swift-UVOT observation
  18. GRB 050422: Swift-BAT refined analysis
  19. GRB 050422: Swift XRT Position
  20. Swift Detection of GRB 050422
  21. GRB 050421: NIR observations
  22. GRB 050416: Optical/NIR observations
  23. GRB 050421: SLOTIS observations
  24. GRB 050421: Further Analysis of IR imaging
  25. GRB050421: Radio Observations
  26. GRB050421: Radio Observations
  27. GRB 050421: Swift-UVOT observation
  28. GRB 050421: IR Observations
  29. GRB 050421: Swift-BAT refined analysis
  30. GRB 050421: ROTSE-III Optical Limits
  31. GRB 050421: NIR observations re-examination
  32. GRB050421
  33. GRB 050421: early Swift XRT analysis results
  34. GRB 050421: NIR observations
  35. GRB050421: P60 Observations
  36. GRB 050421: BOOTES-2 simultaneous optical observations
  37. GRB 050421: Optical observations at the INT
  38. Swift Detection of GRB050421
  39. GRB 050416b: Tentative Swift XRT Position
  40. GRB 050315: potential host galaxy
  41. GRB050326: analysis of the XMM-Newton observation
  42. GRB050418: Null Optical Observations
  43. GRB 050412: Chandra observations
  44. GRB050416A, optical observations
  45. GRB 050418: Swift-BAT refined analysis
  46. Swift-BAT detection of the bright and long GRB 050418
  47. GRB 050416: Mitsume optical observation
  48. GRB 050416 : optical observation at Xinglong observatory
  49. GRB 050416B: optical observations
  50. GRB 050416b: Swift-BAT refined analysis
  51. GRB 050416b: LCO observations
  52. GRB 050416b: LCO observations
  53. GRB050416B: IR observations
  54. GRB 050416: Swift/UVOT refined analysis
  55. Swift-BAT detection of GRB 050416b
  56. IBAS GRB Alert # 2463: not a GRB
  57. GRB050412: Radio Observations
  58. GRB 050416: Swift/UVOT detection of afterglow emission
  59. GRB050416: Refined Swift-XRT analysis
  60. GRB050416: Maidanak optical observations
  61. GRB 050416: Swift-BAT refined analysis
  62. GRB 050416: ART observations
  63. GRB 050416,optical observation
  64. GRB 050416: KAIT observations
  65. GRB050416: P200 NIR Observations
  66. GRB 050416: Swift XRT Position
  67. GRB 050416: Radio observations
  68. Confirmation of OT for GRB050416
  69. GRB050416: P60 Afterglow Candidate
  70. Swift BAT/XRT Detection of GRB 050416
  71. GRB 050412: Subaru observations
  72. GRB 050408: RTT150 optical observations
  73. GRB050408: optical observation
  74. GRB 050412: PROMPT VRcIc Observations
  75. GRB 050408: Kuiper 1.5m observations
  76. GRB 050412: optical limit
  77. GRB 050412: optical observations
  78. GRB 050408: refined XRT analysis, no jet break seen yet
  79. GRB 050412: early Swift XRT analysis results
  80. GRB 050412 : XingLong optical observation
  81. GRB 050412: Swift-BAT refined analysis
  82. GRB 050412: ANU 2.3m observations
  83. GRB 050412: Early Optical/Ultraviolet Observations with
  84. GRB 050412: retraction of UVOT transient report
  85. GRB 050412: UVOT transient not in XRT error circle
  86. GRB 050408: SDSS Field Calibration
  87. GRB 050412: Optical limit
  88. GRB 050412: LCO Optical Observations
  89. GRB 050412: Optical observations
  90. GRB050412: P60 Observations
  91. GRB 050412: Swift XRT Position
  92. GRB050412: optical limit before and during GRB
  93. GRB 050412: LCO optical observations
  94. GRB050412: ROTSE-III Optical Limits
  95. Swift-BAT Detection of GRB 050412: A Bright, Long Burst
  96. GRB 050412: IR and Optical observations
  97. GRB 050412: IR Observations
  98. GRB050408: Radio Observations
  99. GRB 050401: Optical limit
  100. GRB 050408: Optical limit

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