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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. GRB050502: P200 Observations (Correction)
  2. GRB050502: P200 Observations
  3. GRB 050504 : R band observation at Lulin observatory
  4. Swift UVOT observation of GRB 050504
  5. GRB 050504, R band Observations
  6. GRB050504: Faulkes North optical robotic limit
  7. GRB 050502b, V band Observations
  8. GRB050504: P60 Observations
  9. GRB 050504: A long GRB detected with INTEGRAL
  10. GRB (?) 050504: IR Observations, Intriguing Source
  11. GRB 050502b, Optical observations
  12. GRB050502a: P60 Observations (Correction)
  13. GRB050502a: P60 Observations
  14. Renewal of SGR 1806-20 activity
  15. GRB 050502a: RBO Observations
  16. GRB 050502A: WSRT Radio Observations
  17. GRB050502A: Optical Observations
  18. GRB050502B Swift-BAT refined analysis
  19. GRB050502B: I band source in XRT error circle
  20. Swift UVOT refined analysis
  21. Retraction of Swift-BAT trigger 116145
  22. GRB 050502a : R band observation at Lulin observatory
  23. GRB 050502b : optical observation at Lulin observatory
  24. GRB 050502b: Swift XRT Position
  25. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  26. GRB050502B: Optical Limits from ANU 1m
  27. Swift Detection of the Bright Burst GRB050502b
  28. GRB 050502: INTEGRAL results
  29. GRB050502: ANU 1m optical Observations
  30. GRB 050502: Confirmed variability of the afterglow candidate +
  31. GRB 050502: PAIRITEL IR Observations
  32. GRB050502 - Correction on the Optical Candidate from the Liverpool
  33. GRB050502 - Optical Candidate from the Liverpool Telescope
  34. GRB 050502 - A long GRB detected with INTEGRAL
  35. GRB 050502: ROTSE-III Detection of Possible Counterpart
  36. Swift-BAT Trigger 115881 is not a real GRB
  37. Swift/BAT possible detection of a weak burst GRB050430
  38. GRB 050401: Rc observation
  39. GRB050416a: Radio Detection
  40. GRB 050422: Swift-UVOT observation
  41. GRB 050422: Swift-BAT refined analysis
  42. GRB 050422: Swift XRT Position
  43. Swift Detection of GRB 050422
  44. GRB 050421: NIR observations
  45. GRB 050416: Optical/NIR observations
  46. GRB 050421: SLOTIS observations
  47. GRB 050421: Further Analysis of IR imaging
  48. GRB050421: Radio Observations
  49. GRB050421: Radio Observations
  50. GRB 050421: Swift-UVOT observation
  51. GRB 050421: IR Observations
  52. GRB 050421: Swift-BAT refined analysis
  53. GRB 050421: ROTSE-III Optical Limits
  54. GRB 050421: NIR observations re-examination
  55. GRB050421
  56. GRB 050421: early Swift XRT analysis results
  57. GRB 050421: NIR observations
  58. GRB050421: P60 Observations
  59. GRB 050421: BOOTES-2 simultaneous optical observations
  60. GRB 050421: Optical observations at the INT
  61. Swift Detection of GRB050421
  62. GRB 050416b: Tentative Swift XRT Position
  63. GRB 050315: potential host galaxy
  64. GRB050326: analysis of the XMM-Newton observation
  65. GRB050418: Null Optical Observations
  66. GRB 050412: Chandra observations
  67. GRB050416A, optical observations
  68. GRB 050418: Swift-BAT refined analysis
  69. Swift-BAT detection of the bright and long GRB 050418
  70. GRB 050416: Mitsume optical observation
  71. GRB 050416 : optical observation at Xinglong observatory
  72. GRB 050416B: optical observations
  73. GRB 050416b: Swift-BAT refined analysis
  74. GRB 050416b: LCO observations
  75. GRB 050416b: LCO observations
  76. GRB050416B: IR observations
  77. GRB 050416: Swift/UVOT refined analysis
  78. Swift-BAT detection of GRB 050416b
  79. IBAS GRB Alert # 2463: not a GRB
  80. GRB050412: Radio Observations
  81. GRB 050416: Swift/UVOT detection of afterglow emission
  82. GRB050416: Refined Swift-XRT analysis
  83. GRB050416: Maidanak optical observations
  84. GRB 050416: Swift-BAT refined analysis
  85. GRB 050416: ART observations
  86. GRB 050416,optical observation
  87. GRB 050416: KAIT observations
  88. GRB050416: P200 NIR Observations
  89. GRB 050416: Swift XRT Position
  90. GRB 050416: Radio observations
  91. Confirmation of OT for GRB050416
  92. GRB050416: P60 Afterglow Candidate
  93. Swift BAT/XRT Detection of GRB 050416
  94. GRB 050412: Subaru observations
  95. GRB 050408: RTT150 optical observations
  96. GRB050408: optical observation
  97. GRB 050412: PROMPT VRcIc Observations
  98. GRB 050408: Kuiper 1.5m observations
  99. GRB 050412: optical limit
  100. GRB 050412: optical observations

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