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

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