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

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