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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 050509a: Swift XRT Position
  2. Swift Detection of the Burst GRB050509
  3. Swift-BAT detection of GRB 050507
  4. GRB 050505: Keck I-band Magnitude
  5. GRB 050505: early time observations
  6. GRB 050505 - Faulkes Telescope North observations
  7. GRB 050502a: Swift XRT Upper Limit
  8. GRB 050505, simultaneous optical observation
  9. GRB050505: Infrared observations
  10. GRB 050505: Further Swift UVOT observations.
  11. GRB050505: AAVSO observations
  12. GRB050416A : 1 GHz limit from GMRT
  13. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  14. GRB 050505 UVOT
  15. GRB050505: Optical Afterglow Candidate
  16. GRB 050505: Swift XRT Position
  17. GRB050505 Swift-BAT refined analysis
  18. GRB 050502a: Optical Observations
  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. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  24. GRB050502b: Afterglow Confirmation
  25. GRB050502: P200 Observations (Correction)
  26. GRB050502: P200 Observations
  27. GRB 050504 : R band observation at Lulin observatory
  28. Swift UVOT observation of GRB 050504
  29. GRB 050504, R band Observations
  30. GRB050504: Faulkes North optical robotic limit
  31. GRB 050502b, V band Observations
  32. GRB050504: P60 Observations
  33. GRB 050504: A long GRB detected with INTEGRAL
  34. GRB (?) 050504: IR Observations, Intriguing Source
  35. GRB 050502b, Optical observations
  36. GRB050502a: P60 Observations (Correction)
  37. GRB050502a: P60 Observations
  38. Renewal of SGR 1806-20 activity
  39. GRB 050502a: RBO Observations
  40. GRB 050502A: WSRT Radio Observations
  41. GRB050502A: Optical Observations
  42. GRB050502B Swift-BAT refined analysis
  43. GRB050502B: I band source in XRT error circle
  44. Swift UVOT refined analysis
  45. Retraction of Swift-BAT trigger 116145
  46. GRB 050502a : R band observation at Lulin observatory
  47. GRB 050502b : optical observation at Lulin observatory
  48. GRB 050502b: Swift XRT Position
  49. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  50. GRB050502B: Optical Limits from ANU 1m
  51. Swift Detection of the Bright Burst GRB050502b
  52. GRB 050502: INTEGRAL results
  53. GRB050502: ANU 1m optical Observations
  54. GRB 050502: Confirmed variability of the afterglow candidate +
  55. GRB 050502: PAIRITEL IR Observations
  56. GRB050502 - Correction on the Optical Candidate from the Liverpool
  57. GRB050502 - Optical Candidate from the Liverpool Telescope
  58. GRB 050502 - A long GRB detected with INTEGRAL
  59. GRB 050502: ROTSE-III Detection of Possible Counterpart
  60. Swift-BAT Trigger 115881 is not a real GRB
  61. Swift/BAT possible detection of a weak burst GRB050430
  62. GRB 050401: Rc observation
  63. GRB050416a: Radio Detection
  64. GRB 050422: Swift-UVOT observation
  65. GRB 050422: Swift-BAT refined analysis
  66. GRB 050422: Swift XRT Position
  67. Swift Detection of GRB 050422
  68. GRB 050421: NIR observations
  69. GRB 050416: Optical/NIR observations
  70. GRB 050421: SLOTIS observations
  71. GRB 050421: Further Analysis of IR imaging
  72. GRB050421: Radio Observations
  73. GRB050421: Radio Observations
  74. GRB 050421: Swift-UVOT observation
  75. GRB 050421: IR Observations
  76. GRB 050421: Swift-BAT refined analysis
  77. GRB 050421: ROTSE-III Optical Limits
  78. GRB 050421: NIR observations re-examination
  79. GRB050421
  80. GRB 050421: early Swift XRT analysis results
  81. GRB 050421: NIR observations
  82. GRB050421: P60 Observations
  83. GRB 050421: BOOTES-2 simultaneous optical observations
  84. GRB 050421: Optical observations at the INT
  85. Swift Detection of GRB050421
  86. GRB 050416b: Tentative Swift XRT Position
  87. GRB 050315: potential host galaxy
  88. GRB050326: analysis of the XMM-Newton observation
  89. GRB050418: Null Optical Observations
  90. GRB 050412: Chandra observations
  91. GRB050416A, optical observations
  92. GRB 050418: Swift-BAT refined analysis
  93. Swift-BAT detection of the bright and long GRB 050418
  94. GRB 050416: Mitsume optical observation
  95. GRB 050416 : optical observation at Xinglong observatory
  96. GRB 050416B: optical observations
  97. GRB 050416b: Swift-BAT refined analysis
  98. GRB 050416b: LCO observations
  99. GRB 050416b: LCO observations
  100. GRB050416B: IR observations

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