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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 071010B: Bright OT confirmed with TLS
  2. GRB 071011: Optical afterglow candidate
  3. GRB 071011: Swift detection of a burst
  4. Optical Observation: GRB 071010
  5. Optical observations: GRB 071010A
  6. Konus-Wind observation of GRB 071010B
  7. GRB071010B: Swift/XRT detection
  8. GRB 071010B, Swift-BAT refined analysis
  9. GRB 071010A: bright NIR afterglow
  10. GRB 071006, Swift-BAT refined analysis
  11. GRB071008: optical observations
  12. GRB 071010B possible optical transient
  13. GRB 071010A: Keck/LRIS Photometry
  14. GRB 071010B: Swift detection of a burst
  15. GRB 071010: Swift-XRT observation
  16. GRB 071008, Swift-BAT refined analysis
  17. GRB 071010, Swift-BAT refined analysis
  18. Konus-Wind observation of GRB 071006
  19. GRB071008: Swift-XRT observation
  20. GRB 071010 REM NIR observations
  21. GRB 071010: Keck/LRIS Spectroscopy
  22. GRB 071010: TAROT La Silla observatory photometry of the afterglow
  23. GRB 071010: Rapid PROMPT Detections
  24. GRB 071010: Keck Observations of the Afterglow
  25. GRB 071010: TAROT La Silla observatory detection of the afterglow
  26. GRB 071010: Swift detection of a burst
  27. GRB 071006 Swift-BAT detection of a burst
  28. GRB071008: IAC80 observation
  29. GRB 071008: Swift detection of a burst
  30. GRB 071003: XRT refined analysis
  31. GRB070920A: MAGIC telescope GeV observation
  32. Radio detection of GRB 071003 with the VLA
  33. GRB 070810B: further XRT analysis
  34. GRB 071003: VLT spectroscopy
  35. GRB 071003: Keck spectroscopy
  36. Konus-Wind observation of GRB 071003
  37. GRB071003: Faulkes Telescope North observations
  38. GRB 071003: Possible rebrightening
  39. GRB 071003 : Lulin R-band observations
  40. GRB 071003: Swift XRT position
  41. GRB 071003: OA power-law decay indices from KAIT
  42. GRB 071003: Keck HIRES spectroscopy
  43. GRB 071003, Swift-BAT refined analysis
  44. GRB 071003: MARGE Observations
  45. GRB 071003 Optical observations
  46. GRB 071003: P60 Confirmation of Optical Afterglow
  47. GRB 071003: KAIT optical afterglow observations
  48. GRB 071003: Swift detection of a bright burst
  49. GRB 070714B: host galaxy spectroscopic redshift
  50. GRB 071001: Swift-XRT Team refined analysis
  51. GRB 071001, Swift-BAT refined analysis
  52. Faulkes Telescope South observations of GRB 071001
  53. GRB 071001: Swift detection of a burst
  54. VLA observation of GRB 070923
  55. Disregard the Swift-XRT Notices today
  56. GRB 070911, SMARTS optical/IR afterglow observations
  57. GRB070925: Swift-XRT Afterglow confirmation
  58. GRB 070925: Gemini South Imaging
  59. GRB070925: Swift-XRT Position
  60. Update on Swift Status
  61. GRB 070920B: ROTSE-III Early Optical Limits
  62. GRB 070925: a long GRB detected by INTEGRAL
  63. Recent SGR1806-20 Activity
  64. GRB 070923, Swift-BAT refined analysis
  65. GRB 070920B: XRT observations
  66. GRB 070923: Galaxies within BAT localization
  67. GRB 070923: Swift detection of a short hard burst
  68. GRB 070917: Suzaku/WAM observation of the prompt emission
  69. GRB 070920B: TAROT La Silla observatory optical observations
  70. INTEGRAL ToO observations of SGR1806-20
  71. GRB 070920b, SMARTS optical observation
  72. GRB 070917: Confirmation of the X-ray afterglow
  73. GRB 070920b: LCO optical observations
  74. GRB 070920B, Swift-BAT refined analysis
  75. GRB 070911: Swift/BAT and Suzaku/WAM joint spectral analysis
  76. GRB 070920B: NOT optical observations
  77. GRB 070920B: Swift detection of a burst
  78. GRB 070920, Swift-BAT refined analysis
  79. GRB 070920: TAROT Calern observatory optical observations
  80. GRB 070920: Swift detection of a burst
  81. SGR1806-20: Swift-BAT detection of enhanced activity
  82. GRB070917: Confirmation of optical afterglow
  83. GRB920925C: search for host galaxy
  84. GRB070917: optical observations
  85. GRB 070917: P60 Observations
  86. GRB 070917: pseudo-z= 2.40 from prompt emission spectrum
  87. Konus-Wind observation of GRB 070917
  88. Swift Status and XRT Calibration Uncertainties
  89. GRB 070917: Swift-XRT observations
  90. GRB 070917: KAIT optical limits
  91. GRB 070917: MITSuME Akeno Ic upper limit
  92. GRB 070917: R band observations
  93. GRB 070917, Swift-BAT refined analysis
  94. GRB 070917: Swift detection of a bright burst
  95. GRB 070911: Suzaku WAM observation of the prompt emission
  96. GRB 070913: Swift-XRT detection of the possible X-ray afterglow
  97. GRB 070809: The Swift evidence for the SHB nature of this burst
  98. GRB 070913: Afterglow candidate detected by TAROT La Silla observatory
  99. GRB 070913: Swift-BAT refined analysis
  100. GRB 070913: Corrected BAT position

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