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

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