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

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