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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 071013: Swift detection of a burst
  2. GRB 071010C Swift-BAT detection of a burst
  3. GRB 071011: Optical Limit after 13.95hrs
  4. GRB 071011: Xinglong TNT Optical afterglow observations
  5. GRB 071010B correction to GCN 6892 optical observations
  6. GRB 071011: Swift-XRT refined analysis
  7. VLA non-detection of GRB 071010A
  8. GRB 071011: NAYUTA Optical Observation, correction to GCN6886
  9. GRB 071011, Optical afterglow
  10. GRB 071011: Confirmation of P60 optical afterglow
  11. GRB 071010B: Optical Detection
  12. GRB 071011: Kanazawa Optical limits
  13. GRB 071011: P60 Optical Afterglow Candidate
  14. GRB 071011: MARGE Optical Limits
  15. GRB 071010B: Super-LOTIS upper limit
  16. GRB 071010B optical photometry
  17. GRB 071011: XRT afterglow detection
  18. GRB 071010B: Keck/LRIS Spectroscopy
  19. GRB 071011, Swift-BAT refined analysis
  20. GRB 071010B: Gemini Spectroscopic Observations
  21. GRB 071011: Early Super-LOTIS Observations
  22. GRB 071011: NAYUTA Optical Observation
  23. GRB 071010A: Continued Keck Imaging
  24. GRB 071010B: Bright OT confirmed with TLS
  25. GRB 071011: Optical afterglow candidate
  26. GRB 071011: Swift detection of a burst
  27. Optical Observation: GRB 071010
  28. Optical observations: GRB 071010A
  29. Konus-Wind observation of GRB 071010B
  30. GRB071010B: Swift/XRT detection
  31. GRB 071010B, Swift-BAT refined analysis
  32. GRB 071010A: bright NIR afterglow
  33. GRB 071006, Swift-BAT refined analysis
  34. GRB071008: optical observations
  35. GRB 071010B possible optical transient
  36. GRB 071010A: Keck/LRIS Photometry
  37. GRB 071010B: Swift detection of a burst
  38. GRB 071010: Swift-XRT observation
  39. GRB 071008, Swift-BAT refined analysis
  40. GRB 071010, Swift-BAT refined analysis
  41. Konus-Wind observation of GRB 071006
  42. GRB071008: Swift-XRT observation
  43. GRB 071010 REM NIR observations
  44. GRB 071010: Keck/LRIS Spectroscopy
  45. GRB 071010: TAROT La Silla observatory photometry of the afterglow
  46. GRB 071010: Rapid PROMPT Detections
  47. GRB 071010: Keck Observations of the Afterglow
  48. GRB 071010: TAROT La Silla observatory detection of the afterglow
  49. GRB 071010: Swift detection of a burst
  50. GRB 071006 Swift-BAT detection of a burst
  51. GRB071008: IAC80 observation
  52. GRB 071008: Swift detection of a burst
  53. GRB 071003: XRT refined analysis
  54. GRB070920A: MAGIC telescope GeV observation
  55. Radio detection of GRB 071003 with the VLA
  56. GRB 070810B: further XRT analysis
  57. GRB 071003: VLT spectroscopy
  58. GRB 071003: Keck spectroscopy
  59. Konus-Wind observation of GRB 071003
  60. GRB071003: Faulkes Telescope North observations
  61. GRB 071003: Possible rebrightening
  62. GRB 071003 : Lulin R-band observations
  63. GRB 071003: Swift XRT position
  64. GRB 071003: OA power-law decay indices from KAIT
  65. GRB 071003: Keck HIRES spectroscopy
  66. GRB 071003, Swift-BAT refined analysis
  67. GRB 071003: MARGE Observations
  68. GRB 071003 Optical observations
  69. GRB 071003: P60 Confirmation of Optical Afterglow
  70. GRB 071003: KAIT optical afterglow observations
  71. GRB 071003: Swift detection of a bright burst
  72. GRB 070714B: host galaxy spectroscopic redshift
  73. GRB 071001: Swift-XRT Team refined analysis
  74. GRB 071001, Swift-BAT refined analysis
  75. Faulkes Telescope South observations of GRB 071001
  76. GRB 071001: Swift detection of a burst
  77. VLA observation of GRB 070923
  78. Disregard the Swift-XRT Notices today
  79. GRB 070911, SMARTS optical/IR afterglow observations
  80. GRB070925: Swift-XRT Afterglow confirmation
  81. GRB 070925: Gemini South Imaging
  82. GRB070925: Swift-XRT Position
  83. Update on Swift Status
  84. GRB 070920B: ROTSE-III Early Optical Limits
  85. GRB 070925: a long GRB detected by INTEGRAL
  86. Recent SGR1806-20 Activity
  87. GRB 070923, Swift-BAT refined analysis
  88. GRB 070920B: XRT observations
  89. GRB 070923: Galaxies within BAT localization
  90. GRB 070923: Swift detection of a short hard burst
  91. GRB 070917: Suzaku/WAM observation of the prompt emission
  92. GRB 070920B: TAROT La Silla observatory optical observations
  93. INTEGRAL ToO observations of SGR1806-20
  94. GRB 070920b, SMARTS optical observation
  95. GRB 070917: Confirmation of the X-ray afterglow
  96. GRB 070920b: LCO optical observations
  97. GRB 070920B, Swift-BAT refined analysis
  98. GRB 070911: Swift/BAT and Suzaku/WAM joint spectral analysis
  99. GRB 070920B: NOT optical observations
  100. GRB 070920B: Swift detection of a burst

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