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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. GRB050505: AAVSO observations
  2. GRB050416A : 1 GHz limit from GMRT
  3. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  4. GRB 050505 UVOT
  5. GRB050505: Optical Afterglow Candidate
  6. GRB 050505: Swift XRT Position
  7. GRB050505 Swift-BAT refined analysis
  8. GRB 050502a: Optical Observations
  9. GRB 050416b:Swift XRT afterglow upper limits
  10. GRB 050416b:Swift XRT afterglow upper limits
  11. Swift-BAT detection of GRB050505
  12. GRB 050504: Swift XRT position
  13. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  14. GRB050502b: Afterglow Confirmation
  15. GRB050502: P200 Observations (Correction)
  16. GRB050502: P200 Observations
  17. GRB 050504 : R band observation at Lulin observatory
  18. Swift UVOT observation of GRB 050504
  19. GRB 050504, R band Observations
  20. GRB050504: Faulkes North optical robotic limit
  21. GRB 050502b, V band Observations
  22. GRB050504: P60 Observations
  23. GRB 050504: A long GRB detected with INTEGRAL
  24. GRB (?) 050504: IR Observations, Intriguing Source
  25. GRB 050502b, Optical observations
  26. GRB050502a: P60 Observations (Correction)
  27. GRB050502a: P60 Observations
  28. Renewal of SGR 1806-20 activity
  29. GRB 050502a: RBO Observations
  30. GRB 050502A: WSRT Radio Observations
  31. GRB050502A: Optical Observations
  32. GRB050502B Swift-BAT refined analysis
  33. GRB050502B: I band source in XRT error circle
  34. Swift UVOT refined analysis
  35. Retraction of Swift-BAT trigger 116145
  36. GRB 050502a : R band observation at Lulin observatory
  37. GRB 050502b : optical observation at Lulin observatory
  38. GRB 050502b: Swift XRT Position
  39. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  40. GRB050502B: Optical Limits from ANU 1m
  41. Swift Detection of the Bright Burst GRB050502b
  42. GRB 050502: INTEGRAL results
  43. GRB050502: ANU 1m optical Observations
  44. GRB 050502: Confirmed variability of the afterglow candidate +
  45. GRB 050502: PAIRITEL IR Observations
  46. GRB050502 - Correction on the Optical Candidate from the Liverpool
  47. GRB050502 - Optical Candidate from the Liverpool Telescope
  48. GRB 050502 - A long GRB detected with INTEGRAL
  49. GRB 050502: ROTSE-III Detection of Possible Counterpart
  50. Swift-BAT Trigger 115881 is not a real GRB
  51. Swift/BAT possible detection of a weak burst GRB050430
  52. GRB 050401: Rc observation
  53. GRB050416a: Radio Detection
  54. GRB 050422: Swift-UVOT observation
  55. GRB 050422: Swift-BAT refined analysis
  56. GRB 050422: Swift XRT Position
  57. Swift Detection of GRB 050422
  58. GRB 050421: NIR observations
  59. GRB 050416: Optical/NIR observations
  60. GRB 050421: SLOTIS observations
  61. GRB 050421: Further Analysis of IR imaging
  62. GRB050421: Radio Observations
  63. GRB050421: Radio Observations
  64. GRB 050421: Swift-UVOT observation
  65. GRB 050421: IR Observations
  66. GRB 050421: Swift-BAT refined analysis
  67. GRB 050421: ROTSE-III Optical Limits
  68. GRB 050421: NIR observations re-examination
  69. GRB050421
  70. GRB 050421: early Swift XRT analysis results
  71. GRB 050421: NIR observations
  72. GRB050421: P60 Observations
  73. GRB 050421: BOOTES-2 simultaneous optical observations
  74. GRB 050421: Optical observations at the INT
  75. Swift Detection of GRB050421
  76. GRB 050416b: Tentative Swift XRT Position
  77. GRB 050315: potential host galaxy
  78. GRB050326: analysis of the XMM-Newton observation
  79. GRB050418: Null Optical Observations
  80. GRB 050412: Chandra observations
  81. GRB050416A, optical observations
  82. GRB 050418: Swift-BAT refined analysis
  83. Swift-BAT detection of the bright and long GRB 050418
  84. GRB 050416: Mitsume optical observation
  85. GRB 050416 : optical observation at Xinglong observatory
  86. GRB 050416B: optical observations
  87. GRB 050416b: Swift-BAT refined analysis
  88. GRB 050416b: LCO observations
  89. GRB 050416b: LCO observations
  90. GRB050416B: IR observations
  91. GRB 050416: Swift/UVOT refined analysis
  92. Swift-BAT detection of GRB 050416b
  93. IBAS GRB Alert # 2463: not a GRB
  94. GRB050412: Radio Observations
  95. GRB 050416: Swift/UVOT detection of afterglow emission
  96. GRB050416: Refined Swift-XRT analysis
  97. GRB050416: Maidanak optical observations
  98. GRB 050416: Swift-BAT refined analysis
  99. GRB 050416: ART observations
  100. GRB 050416,optical observation

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