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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. Konus-Wind observation of GRB 071003
  2. GRB071003: Faulkes Telescope North observations
  3. GRB 071003: Possible rebrightening
  4. GRB 071003 : Lulin R-band observations
  5. GRB 071003: Swift XRT position
  6. GRB 071003: OA power-law decay indices from KAIT
  7. GRB 071003: Keck HIRES spectroscopy
  8. GRB 071003, Swift-BAT refined analysis
  9. GRB 071003: MARGE Observations
  10. GRB 071003 Optical observations
  11. GRB 071003: P60 Confirmation of Optical Afterglow
  12. GRB 071003: KAIT optical afterglow observations
  13. GRB 071003: Swift detection of a bright burst
  14. GRB 070714B: host galaxy spectroscopic redshift
  15. GRB 071001: Swift-XRT Team refined analysis
  16. GRB 071001, Swift-BAT refined analysis
  17. Faulkes Telescope South observations of GRB 071001
  18. GRB 071001: Swift detection of a burst
  19. VLA observation of GRB 070923
  20. Disregard the Swift-XRT Notices today
  21. GRB 070911, SMARTS optical/IR afterglow observations
  22. GRB070925: Swift-XRT Afterglow confirmation
  23. GRB 070925: Gemini South Imaging
  24. GRB070925: Swift-XRT Position
  25. Update on Swift Status
  26. GRB 070920B: ROTSE-III Early Optical Limits
  27. GRB 070925: a long GRB detected by INTEGRAL
  28. Recent SGR1806-20 Activity
  29. GRB 070923, Swift-BAT refined analysis
  30. GRB 070920B: XRT observations
  31. GRB 070923: Galaxies within BAT localization
  32. GRB 070923: Swift detection of a short hard burst
  33. GRB 070917: Suzaku/WAM observation of the prompt emission
  34. GRB 070920B: TAROT La Silla observatory optical observations
  35. INTEGRAL ToO observations of SGR1806-20
  36. GRB 070920b, SMARTS optical observation
  37. GRB 070917: Confirmation of the X-ray afterglow
  38. GRB 070920b: LCO optical observations
  39. GRB 070920B, Swift-BAT refined analysis
  40. GRB 070911: Swift/BAT and Suzaku/WAM joint spectral analysis
  41. GRB 070920B: NOT optical observations
  42. GRB 070920B: Swift detection of a burst
  43. GRB 070920, Swift-BAT refined analysis
  44. GRB 070920: TAROT Calern observatory optical observations
  45. GRB 070920: Swift detection of a burst
  46. SGR1806-20: Swift-BAT detection of enhanced activity
  47. GRB070917: Confirmation of optical afterglow
  48. GRB920925C: search for host galaxy
  49. GRB070917: optical observations
  50. GRB 070917: P60 Observations
  51. GRB 070917: pseudo-z= 2.40 from prompt emission spectrum
  52. Konus-Wind observation of GRB 070917
  53. Swift Status and XRT Calibration Uncertainties
  54. GRB 070917: Swift-XRT observations
  55. GRB 070917: KAIT optical limits
  56. GRB 070917: MITSuME Akeno Ic upper limit
  57. GRB 070917: R band observations
  58. GRB 070917, Swift-BAT refined analysis
  59. GRB 070917: Swift detection of a bright burst
  60. GRB 070911: Suzaku WAM observation of the prompt emission
  61. GRB 070913: Swift-XRT detection of the possible X-ray afterglow
  62. GRB 070809: The Swift evidence for the SHB nature of this burst
  63. GRB 070913: Afterglow candidate detected by TAROT La Silla observatory
  64. GRB 070913: Swift-BAT refined analysis
  65. GRB 070913: Corrected BAT position
  66. GRB 070913: SMARTS optical/IR observations
  67. GRB 070913: TAROT La Silla observatory optical observations
  68. GRB 070913: Swift detection of a burst
  69. Swift-BAT Notices back to autonomous real-time distribution
  70. GRB 070911: PAIRITEL IR Observations
  71. GRB 070911: Swift XRT refined analysis
  72. GRB 070911, Swift-BAT refined analysis
  73. GRB 070911: Swift detection of a burst
  74. IPN search for a GRB associated with TAROT transient on August 31
  75. Intense burst from SGR 1806-20 detected on September 7
  76. GRB 070809: Confirmation of optical transient
  77. Observations of possible TAROT GRB transient near IC 4779
  78. Candidate Orphan GRB Optical Transient in IC 4779
  79. GRB 070810b: Image Subtraction of Multiple Keck Observations
  80. Las Campanas observations of possible TAROT GRB transient near IC
  81. Orphan GRB candidate in IC 4779 at TAROT La Silla observatory
  82. Konus-Wind observation of GRB 070824
  83. GRB 070824 - Combined SuperAGILE/IPN Localization
  84. Konus-Wind observation of very bright GRB 070821
  85. GRB 070731: Swift/UVOT Upper Limit
  86. IPN Localization of GRB 070821 (long, very bright)
  87. GRB 070805: UVOT afterglow candidate retraction
  88. GRB070810b: optical candidate
  89. GRB 070810A: ROTSE-III Refined Analysis
  90. Swift observatory off line
  91. GRB 061110A: redshift confirmed
  92. GRB 070810B : Faulkes Telescope South Observations
  93. GRB 070810A: Continued Keck Imaging
  94. GRB 070810B: Keck spectroscopy of possible host galaxies
  95. GRB070810B: Swift/UVOT Upper Limits
  96. GRB 070810B: XRT refined analysis
  97. GRB 070810B, Swift-BAT refined analysis
  98. GRB 070810: MASTER optical observation
  99. GRB 070809: Swift/UVOT Corrected Photometry
  100. Swift Alert 070810.8: MASTER optical observation

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