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

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