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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. VLA observation of GRB 070923
  2. Disregard the Swift-XRT Notices today
  3. GRB 070911, SMARTS optical/IR afterglow observations
  4. GRB070925: Swift-XRT Afterglow confirmation
  5. GRB 070925: Gemini South Imaging
  6. GRB070925: Swift-XRT Position
  7. Update on Swift Status
  8. GRB 070920B: ROTSE-III Early Optical Limits
  9. GRB 070925: a long GRB detected by INTEGRAL
  10. Recent SGR1806-20 Activity
  11. GRB 070923, Swift-BAT refined analysis
  12. GRB 070920B: XRT observations
  13. GRB 070923: Galaxies within BAT localization
  14. GRB 070923: Swift detection of a short hard burst
  15. GRB 070917: Suzaku/WAM observation of the prompt emission
  16. GRB 070920B: TAROT La Silla observatory optical observations
  17. INTEGRAL ToO observations of SGR1806-20
  18. GRB 070920b, SMARTS optical observation
  19. GRB 070917: Confirmation of the X-ray afterglow
  20. GRB 070920b: LCO optical observations
  21. GRB 070920B, Swift-BAT refined analysis
  22. GRB 070911: Swift/BAT and Suzaku/WAM joint spectral analysis
  23. GRB 070920B: NOT optical observations
  24. GRB 070920B: Swift detection of a burst
  25. GRB 070920, Swift-BAT refined analysis
  26. GRB 070920: TAROT Calern observatory optical observations
  27. GRB 070920: Swift detection of a burst
  28. SGR1806-20: Swift-BAT detection of enhanced activity
  29. GRB070917: Confirmation of optical afterglow
  30. GRB920925C: search for host galaxy
  31. GRB070917: optical observations
  32. GRB 070917: P60 Observations
  33. GRB 070917: pseudo-z= 2.40 from prompt emission spectrum
  34. Konus-Wind observation of GRB 070917
  35. Swift Status and XRT Calibration Uncertainties
  36. GRB 070917: Swift-XRT observations
  37. GRB 070917: KAIT optical limits
  38. GRB 070917: MITSuME Akeno Ic upper limit
  39. GRB 070917: R band observations
  40. GRB 070917, Swift-BAT refined analysis
  41. GRB 070917: Swift detection of a bright burst
  42. GRB 070911: Suzaku WAM observation of the prompt emission
  43. GRB 070913: Swift-XRT detection of the possible X-ray afterglow
  44. GRB 070809: The Swift evidence for the SHB nature of this burst
  45. GRB 070913: Afterglow candidate detected by TAROT La Silla observatory
  46. GRB 070913: Swift-BAT refined analysis
  47. GRB 070913: Corrected BAT position
  48. GRB 070913: SMARTS optical/IR observations
  49. GRB 070913: TAROT La Silla observatory optical observations
  50. GRB 070913: Swift detection of a burst
  51. Swift-BAT Notices back to autonomous real-time distribution
  52. GRB 070911: PAIRITEL IR Observations
  53. GRB 070911: Swift XRT refined analysis
  54. GRB 070911, Swift-BAT refined analysis
  55. GRB 070911: Swift detection of a burst
  56. IPN search for a GRB associated with TAROT transient on August 31
  57. Intense burst from SGR 1806-20 detected on September 7
  58. GRB 070809: Confirmation of optical transient
  59. Observations of possible TAROT GRB transient near IC 4779
  60. Candidate Orphan GRB Optical Transient in IC 4779
  61. GRB 070810b: Image Subtraction of Multiple Keck Observations
  62. Las Campanas observations of possible TAROT GRB transient near IC
  63. Orphan GRB candidate in IC 4779 at TAROT La Silla observatory
  64. Konus-Wind observation of GRB 070824
  65. GRB 070824 - Combined SuperAGILE/IPN Localization
  66. Konus-Wind observation of very bright GRB 070821
  67. GRB 070731: Swift/UVOT Upper Limit
  68. IPN Localization of GRB 070821 (long, very bright)
  69. GRB 070805: UVOT afterglow candidate retraction
  70. GRB070810b: optical candidate
  71. GRB 070810A: ROTSE-III Refined Analysis
  72. Swift observatory off line
  73. GRB 061110A: redshift confirmed
  74. GRB 070810B : Faulkes Telescope South Observations
  75. GRB 070810A: Continued Keck Imaging
  76. GRB 070810B: Keck spectroscopy of possible host galaxies
  77. GRB070810B: Swift/UVOT Upper Limits
  78. GRB 070810B: XRT refined analysis
  79. GRB 070810B, Swift-BAT refined analysis
  80. GRB 070810: MASTER optical observation
  81. GRB 070809: Swift/UVOT Corrected Photometry
  82. Swift Alert 070810.8: MASTER optical observation
  83. Swift Trigger 287421: False trigger due to star tracker loss
  84. GRB 070810A: Swift-BAT refined analysis
  85. GRB 070810B: Xinglong TNT optical Upper Limit
  86. GRB070810B: Optical observations with KANATA
  87. A giant outburst from Cygnus X-1 detected by Konus-Wind and Suzaku-WAM
  88. GRB 070809: Swift/UVOT Upper Limits
  89. GRB 070810B: Swift detection of a short burst
  90. VLA upper limit on the short hard burst GRB 070729
  91. GRB 070810: Keck redshift and photometry
  92. No radio detection in superAGILE burst 070724B
  93. GRB 070809: Keck Imaging
  94. GRB 070810: Swift-XRT Team Refined Analysis
  95. GRB 070809: Swift-XRT refined analysis
  96. GRB 070810: enhanced Swift-XRT position
  97. GRB 070810: Swift/UVOT Optical Counterpart
  98. GRB 070810: ROTSE-III Detection of Optical Counterpart
  99. GRB 070810: Swift detection of a burst
  100. GRB 070809, Swift-BAT refined analysis

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