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

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