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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. Optical observations: GRB 071010A
  2. Konus-Wind observation of GRB 071010B
  3. GRB071010B: Swift/XRT detection
  4. GRB 071010B, Swift-BAT refined analysis
  5. GRB 071010A: bright NIR afterglow
  6. GRB 071006, Swift-BAT refined analysis
  7. GRB071008: optical observations
  8. GRB 071010B possible optical transient
  9. GRB 071010A: Keck/LRIS Photometry
  10. GRB 071010B: Swift detection of a burst
  11. GRB 071010: Swift-XRT observation
  12. GRB 071008, Swift-BAT refined analysis
  13. GRB 071010, Swift-BAT refined analysis
  14. Konus-Wind observation of GRB 071006
  15. GRB071008: Swift-XRT observation
  16. GRB 071010 REM NIR observations
  17. GRB 071010: Keck/LRIS Spectroscopy
  18. GRB 071010: TAROT La Silla observatory photometry of the afterglow
  19. GRB 071010: Rapid PROMPT Detections
  20. GRB 071010: Keck Observations of the Afterglow
  21. GRB 071010: TAROT La Silla observatory detection of the afterglow
  22. GRB 071010: Swift detection of a burst
  23. GRB 071006 Swift-BAT detection of a burst
  24. GRB071008: IAC80 observation
  25. GRB 071008: Swift detection of a burst
  26. GRB 071003: XRT refined analysis
  27. GRB070920A: MAGIC telescope GeV observation
  28. Radio detection of GRB 071003 with the VLA
  29. GRB 070810B: further XRT analysis
  30. GRB 071003: VLT spectroscopy
  31. GRB 071003: Keck spectroscopy
  32. Konus-Wind observation of GRB 071003
  33. GRB071003: Faulkes Telescope North observations
  34. GRB 071003: Possible rebrightening
  35. GRB 071003 : Lulin R-band observations
  36. GRB 071003: Swift XRT position
  37. GRB 071003: OA power-law decay indices from KAIT
  38. GRB 071003: Keck HIRES spectroscopy
  39. GRB 071003, Swift-BAT refined analysis
  40. GRB 071003: MARGE Observations
  41. GRB 071003 Optical observations
  42. GRB 071003: P60 Confirmation of Optical Afterglow
  43. GRB 071003: KAIT optical afterglow observations
  44. GRB 071003: Swift detection of a bright burst
  45. GRB 070714B: host galaxy spectroscopic redshift
  46. GRB 071001: Swift-XRT Team refined analysis
  47. GRB 071001, Swift-BAT refined analysis
  48. Faulkes Telescope South observations of GRB 071001
  49. GRB 071001: Swift detection of a burst
  50. VLA observation of GRB 070923
  51. Disregard the Swift-XRT Notices today
  52. GRB 070911, SMARTS optical/IR afterglow observations
  53. GRB070925: Swift-XRT Afterglow confirmation
  54. GRB 070925: Gemini South Imaging
  55. GRB070925: Swift-XRT Position
  56. Update on Swift Status
  57. GRB 070920B: ROTSE-III Early Optical Limits
  58. GRB 070925: a long GRB detected by INTEGRAL
  59. Recent SGR1806-20 Activity
  60. GRB 070923, Swift-BAT refined analysis
  61. GRB 070920B: XRT observations
  62. GRB 070923: Galaxies within BAT localization
  63. GRB 070923: Swift detection of a short hard burst
  64. GRB 070917: Suzaku/WAM observation of the prompt emission
  65. GRB 070920B: TAROT La Silla observatory optical observations
  66. INTEGRAL ToO observations of SGR1806-20
  67. GRB 070920b, SMARTS optical observation
  68. GRB 070917: Confirmation of the X-ray afterglow
  69. GRB 070920b: LCO optical observations
  70. GRB 070920B, Swift-BAT refined analysis
  71. GRB 070911: Swift/BAT and Suzaku/WAM joint spectral analysis
  72. GRB 070920B: NOT optical observations
  73. GRB 070920B: Swift detection of a burst
  74. GRB 070920, Swift-BAT refined analysis
  75. GRB 070920: TAROT Calern observatory optical observations
  76. GRB 070920: Swift detection of a burst
  77. SGR1806-20: Swift-BAT detection of enhanced activity
  78. GRB070917: Confirmation of optical afterglow
  79. GRB920925C: search for host galaxy
  80. GRB070917: optical observations
  81. GRB 070917: P60 Observations
  82. GRB 070917: pseudo-z= 2.40 from prompt emission spectrum
  83. Konus-Wind observation of GRB 070917
  84. Swift Status and XRT Calibration Uncertainties
  85. GRB 070917: Swift-XRT observations
  86. GRB 070917: KAIT optical limits
  87. GRB 070917: MITSuME Akeno Ic upper limit
  88. GRB 070917: R band observations
  89. GRB 070917, Swift-BAT refined analysis
  90. GRB 070917: Swift detection of a bright burst
  91. GRB 070911: Suzaku WAM observation of the prompt emission
  92. GRB 070913: Swift-XRT detection of the possible X-ray afterglow
  93. GRB 070809: The Swift evidence for the SHB nature of this burst
  94. GRB 070913: Afterglow candidate detected by TAROT La Silla observatory
  95. GRB 070913: Swift-BAT refined analysis
  96. GRB 070913: Corrected BAT position
  97. GRB 070913: SMARTS optical/IR observations
  98. GRB 070913: TAROT La Silla observatory optical observations
  99. GRB 070913: Swift detection of a burst
  100. Swift-BAT Notices back to autonomous real-time distribution

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