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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. Swift-BAT detection of GRB 050507
  2. GRB 050505: Keck I-band Magnitude
  3. GRB 050505: early time observations
  4. GRB 050505 - Faulkes Telescope North observations
  5. GRB 050502a: Swift XRT Upper Limit
  6. GRB 050505, simultaneous optical observation
  7. GRB050505: Infrared observations
  8. GRB 050505: Further Swift UVOT observations.
  9. GRB050505: AAVSO observations
  10. GRB050416A : 1 GHz limit from GMRT
  11. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  12. GRB 050505 UVOT
  13. GRB050505: Optical Afterglow Candidate
  14. GRB 050505: Swift XRT Position
  15. GRB050505 Swift-BAT refined analysis
  16. GRB 050502a: Optical Observations
  17. GRB 050416b:Swift XRT afterglow upper limits
  18. GRB 050416b:Swift XRT afterglow upper limits
  19. Swift-BAT detection of GRB050505
  20. GRB 050504: Swift XRT position
  21. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  22. GRB050502b: Afterglow Confirmation
  23. GRB050502: P200 Observations (Correction)
  24. GRB050502: P200 Observations
  25. GRB 050504 : R band observation at Lulin observatory
  26. Swift UVOT observation of GRB 050504
  27. GRB 050504, R band Observations
  28. GRB050504: Faulkes North optical robotic limit
  29. GRB 050502b, V band Observations
  30. GRB050504: P60 Observations
  31. GRB 050504: A long GRB detected with INTEGRAL
  32. GRB (?) 050504: IR Observations, Intriguing Source
  33. GRB 050502b, Optical observations
  34. GRB050502a: P60 Observations (Correction)
  35. GRB050502a: P60 Observations
  36. Renewal of SGR 1806-20 activity
  37. GRB 050502a: RBO Observations
  38. GRB 050502A: WSRT Radio Observations
  39. GRB050502A: Optical Observations
  40. GRB050502B Swift-BAT refined analysis
  41. GRB050502B: I band source in XRT error circle
  42. Swift UVOT refined analysis
  43. Retraction of Swift-BAT trigger 116145
  44. GRB 050502a : R band observation at Lulin observatory
  45. GRB 050502b : optical observation at Lulin observatory
  46. GRB 050502b: Swift XRT Position
  47. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  48. GRB050502B: Optical Limits from ANU 1m
  49. Swift Detection of the Bright Burst GRB050502b
  50. GRB 050502: INTEGRAL results
  51. GRB050502: ANU 1m optical Observations
  52. GRB 050502: Confirmed variability of the afterglow candidate +
  53. GRB 050502: PAIRITEL IR Observations
  54. GRB050502 - Correction on the Optical Candidate from the Liverpool
  55. GRB050502 - Optical Candidate from the Liverpool Telescope
  56. GRB 050502 - A long GRB detected with INTEGRAL
  57. GRB 050502: ROTSE-III Detection of Possible Counterpart
  58. Swift-BAT Trigger 115881 is not a real GRB
  59. Swift/BAT possible detection of a weak burst GRB050430
  60. GRB 050401: Rc observation
  61. GRB050416a: Radio Detection
  62. GRB 050422: Swift-UVOT observation
  63. GRB 050422: Swift-BAT refined analysis
  64. GRB 050422: Swift XRT Position
  65. Swift Detection of GRB 050422
  66. GRB 050421: NIR observations
  67. GRB 050416: Optical/NIR observations
  68. GRB 050421: SLOTIS observations
  69. GRB 050421: Further Analysis of IR imaging
  70. GRB050421: Radio Observations
  71. GRB050421: Radio Observations
  72. GRB 050421: Swift-UVOT observation
  73. GRB 050421: IR Observations
  74. GRB 050421: Swift-BAT refined analysis
  75. GRB 050421: ROTSE-III Optical Limits
  76. GRB 050421: NIR observations re-examination
  77. GRB050421
  78. GRB 050421: early Swift XRT analysis results
  79. GRB 050421: NIR observations
  80. GRB050421: P60 Observations
  81. GRB 050421: BOOTES-2 simultaneous optical observations
  82. GRB 050421: Optical observations at the INT
  83. Swift Detection of GRB050421
  84. GRB 050416b: Tentative Swift XRT Position
  85. GRB 050315: potential host galaxy
  86. GRB050326: analysis of the XMM-Newton observation
  87. GRB050418: Null Optical Observations
  88. GRB 050412: Chandra observations
  89. GRB050416A, optical observations
  90. GRB 050418: Swift-BAT refined analysis
  91. Swift-BAT detection of the bright and long GRB 050418
  92. GRB 050416: Mitsume optical observation
  93. GRB 050416 : optical observation at Xinglong observatory
  94. GRB 050416B: optical observations
  95. GRB 050416b: Swift-BAT refined analysis
  96. GRB 050416b: LCO observations
  97. GRB 050416b: LCO observations
  98. GRB050416B: IR observations
  99. GRB 050416: Swift/UVOT refined analysis
  100. Swift-BAT detection of GRB 050416b

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