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

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