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

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