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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"

18395 results found.

  1. GRB 050509A: Optical 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: early time observations
  11. GRB 050505 - Faulkes Telescope North observations
  12. GRB 050502a: Swift XRT Upper Limit
  13. GRB 050505, simultaneous optical observation
  14. GRB 050505: Further Swift UVOT observations.
  15. GRB050416A : 1 GHz limit from GMRT
  16. GRB 050505 UVOT
  17. GRB 050505: Swift XRT Position
  18. GRB050505 Swift-BAT refined analysis
  19. GRB 050416b:Swift XRT afterglow upper limits
  20. GRB 050416b:Swift XRT afterglow upper limits
  21. Swift-BAT detection of GRB050505
  22. GRB 050504: Swift XRT position
  23. Swift UVOT observation of GRB 050504
  24. GRB 050502b, V band Observations
  25. GRB050502B Swift-BAT refined analysis
  26. GRB050502B: I band source in XRT error circle
  27. Swift UVOT refined analysis
  28. Retraction of Swift-BAT trigger 116145
  29. GRB 050502b : optical observation at Lulin observatory
  30. GRB 050502b: Swift XRT Position
  31. GRB050502B: Optical Limits from ANU 1m
  32. Swift Detection of the Bright Burst GRB050502b
  33. GRB050502: ANU 1m optical Observations
  34. Swift-BAT Trigger 115881 is not a real GRB
  35. Swift/BAT possible detection of a weak burst GRB050430
  36. GRB 050401: Rc observation
  37. GRB050416a: Radio Detection
  38. GRB 050422: Swift-UVOT observation
  39. GRB 050422: Swift-BAT refined analysis
  40. GRB 050422: Swift XRT Position
  41. Swift Detection of GRB 050422
  42. GRB 050421: SLOTIS observations
  43. GRB050421: Radio Observations
  44. GRB050421: Radio Observations
  45. GRB 050421: Swift-UVOT observation
  46. GRB 050421: Swift-BAT refined analysis
  47. GRB 050421: ROTSE-III Optical Limits
  48. GRB 050421: early Swift XRT analysis results
  49. GRB 050421: BOOTES-2 simultaneous optical observations
  50. GRB 050421: Optical observations at the INT
  51. Swift Detection of GRB050421
  52. GRB 050416b: Tentative Swift XRT Position
  53. GRB050326: analysis of the XMM-Newton observation
  54. GRB 050418: Swift-BAT refined analysis
  55. Swift-BAT detection of the bright and long GRB 050418
  56. GRB 050416B: optical observations
  57. GRB 050416b: Swift-BAT refined analysis
  58. GRB 050416: Swift/UVOT refined analysis
  59. Swift-BAT detection of GRB 050416b
  60. GRB050412: Radio Observations
  61. GRB 050416: Swift/UVOT detection of afterglow emission
  62. GRB050416: Refined Swift-XRT analysis
  63. GRB050416: Maidanak optical observations
  64. GRB 050416: Swift-BAT refined analysis
  65. GRB 050416,optical observation
  66. GRB 050416: KAIT observations
  67. GRB 050416: Swift XRT Position
  68. GRB 050416: Radio observations
  69. Confirmation of OT for GRB050416
  70. GRB050416: P60 Afterglow Candidate
  71. Swift BAT/XRT Detection of GRB 050416
  72. GRB 050412: Subaru observations
  73. GRB 050412: optical limit
  74. GRB 050412: optical observations
  75. GRB 050408: refined XRT analysis, no jet break seen yet
  76. GRB 050412: early Swift XRT analysis results
  77. GRB 050412: Swift-BAT refined analysis
  78. GRB 050412: ANU 2.3m observations
  79. GRB 050412: Early Optical/Ultraviolet Observations with
  80. GRB 050412: retraction of UVOT transient report
  81. GRB 050412: UVOT transient not in XRT error circle
  82. GRB 050412: Swift XRT Position
  83. GRB050412: optical limit before and during GRB
  84. GRB050412: ROTSE-III Optical Limits
  85. Swift-BAT Detection of GRB 050412: A Bright, Long Burst
  86. GRB 050412: IR Observations
  87. GRB 050410: Early Optical/Ultraviolet Observations with Swift/UVOT
  88. GRB 050410, optical observations
  89. GRB 050408: Early Optical/Ultraviolet Observations with Swift/UVOT
  90. GRB 050410 R band Optical Observations
  91. GRB050410 : Null detection report
  92. GRB 050410, optical observations
  93. GRB050410: Radio Observations
  94. GRB 050408: Swift XRT measurement of possible jet break
  95. GRB050410: MASTER optical observations
  96. GRB 050410: Early observations with Swift-UVOT
  97. Swift-BAT detection of GRB 050410
  98. GRB 050410: Swift XRT Position
  99. GRB 050408: Properties of the Host Galaxy
  100. GRB 050408: Swift XRT analysis

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