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

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