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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 050509b: PAIRITEL and WIYN Observations
  2. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  3. GRB 050509b: optical observations
  4. GRB 050509b: Swift XRT Position
  5. GRB 050509B: ROTSE-III Optical Limits
  6. Swift Detection of GRB050509b: A short duration burst
  7. GRB 050509a: Swift XRT Position
  8. Swift Detection of the Burst GRB050509
  9. Swift-BAT detection of GRB 050507
  10. GRB 050505: Keck I-band Magnitude
  11. GRB 050505: early time observations
  12. GRB 050505 - Faulkes Telescope North observations
  13. GRB 050502a: Swift XRT Upper Limit
  14. GRB 050505, simultaneous optical observation
  15. GRB050505: Infrared observations
  16. GRB 050505: Further Swift UVOT observations.
  17. GRB050505: AAVSO observations
  18. GRB050416A : 1 GHz limit from GMRT
  19. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  20. GRB 050505 UVOT
  21. GRB050505: Optical Afterglow Candidate
  22. GRB 050505: Swift XRT Position
  23. GRB050505 Swift-BAT refined analysis
  24. GRB 050502a: Optical Observations
  25. GRB 050416b:Swift XRT afterglow upper limits
  26. GRB 050416b:Swift XRT afterglow upper limits
  27. Swift-BAT detection of GRB050505
  28. GRB 050504: Swift XRT position
  29. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  30. GRB050502b: Afterglow Confirmation
  31. GRB050502: P200 Observations (Correction)
  32. GRB050502: P200 Observations
  33. GRB 050504 : R band observation at Lulin observatory
  34. Swift UVOT observation of GRB 050504
  35. GRB 050504, R band Observations
  36. GRB050504: Faulkes North optical robotic limit
  37. GRB 050502b, V band Observations
  38. GRB050504: P60 Observations
  39. GRB 050504: A long GRB detected with INTEGRAL
  40. GRB (?) 050504: IR Observations, Intriguing Source
  41. GRB 050502b, Optical observations
  42. GRB050502a: P60 Observations (Correction)
  43. GRB050502a: P60 Observations
  44. Renewal of SGR 1806-20 activity
  45. GRB 050502a: RBO Observations
  46. GRB 050502A: WSRT Radio Observations
  47. GRB050502A: Optical Observations
  48. GRB050502B Swift-BAT refined analysis
  49. GRB050502B: I band source in XRT error circle
  50. Swift UVOT refined analysis
  51. Retraction of Swift-BAT trigger 116145
  52. GRB 050502a : R band observation at Lulin observatory
  53. GRB 050502b : optical observation at Lulin observatory
  54. GRB 050502b: Swift XRT Position
  55. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  56. GRB050502B: Optical Limits from ANU 1m
  57. Swift Detection of the Bright Burst GRB050502b
  58. GRB 050502: INTEGRAL results
  59. GRB050502: ANU 1m optical Observations
  60. GRB 050502: Confirmed variability of the afterglow candidate +
  61. GRB 050502: PAIRITEL IR Observations
  62. GRB050502 - Correction on the Optical Candidate from the Liverpool
  63. GRB050502 - Optical Candidate from the Liverpool Telescope
  64. GRB 050502 - A long GRB detected with INTEGRAL
  65. GRB 050502: ROTSE-III Detection of Possible Counterpart
  66. Swift-BAT Trigger 115881 is not a real GRB
  67. Swift/BAT possible detection of a weak burst GRB050430
  68. GRB 050401: Rc observation
  69. GRB050416a: Radio Detection
  70. GRB 050422: Swift-UVOT observation
  71. GRB 050422: Swift-BAT refined analysis
  72. GRB 050422: Swift XRT Position
  73. Swift Detection of GRB 050422
  74. GRB 050421: NIR observations
  75. GRB 050416: Optical/NIR observations
  76. GRB 050421: SLOTIS observations
  77. GRB 050421: Further Analysis of IR imaging
  78. GRB050421: Radio Observations
  79. GRB050421: Radio Observations
  80. GRB 050421: Swift-UVOT observation
  81. GRB 050421: IR Observations
  82. GRB 050421: Swift-BAT refined analysis
  83. GRB 050421: ROTSE-III Optical Limits
  84. GRB 050421: NIR observations re-examination
  85. GRB050421
  86. GRB 050421: early Swift XRT analysis results
  87. GRB 050421: NIR observations
  88. GRB050421: P60 Observations
  89. GRB 050421: BOOTES-2 simultaneous optical observations
  90. GRB 050421: Optical observations at the INT
  91. Swift Detection of GRB050421
  92. GRB 050416b: Tentative Swift XRT Position
  93. GRB 050315: potential host galaxy
  94. GRB050326: analysis of the XMM-Newton observation
  95. GRB050418: Null Optical Observations
  96. GRB 050412: Chandra observations
  97. GRB050416A, optical observations
  98. GRB 050418: Swift-BAT refined analysis
  99. Swift-BAT detection of the bright and long GRB 050418
  100. GRB 050416: Mitsume optical observation

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