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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 060807: Detection of a possible host galaxy
  2. GRB 060923A: VLA K-band Observations
  3. GRB060930: Faulkes Telescope South observation
  4. GRB 060930: Xinglong TNT optical observations
  5. GRB 060929: Further XRT Refined Analysis
  6. GRB 060929: Swift/UVOT Optical Observations
  7. GRB 060930: ROTSE-III Optical Limits
  8. GRB 060930: A long X-ray rich GRB detected by INTEGRAL
  9. GRB 060927 : GAO 150cm telescope optical observation
  10. GRB060929: Swift-XRT refined analysis.
  11. GRB 060929, Swift-BAT further refined analysis - late-time flare
  12. GRB 060929: TNG K-band observations
  13. GRB 060929, Swift-BAT refined analysis
  14. GRB060929: Optical limit
  15. GRB 060929: BART observation
  16. GRB 060929: MASTER-VWF-Kislovodsk observations
  17. GRB 060929: BOOTES-IR & OSN observations
  18. Liverpool Telescope observations of GRB 060929
  19. GRB 060929: Swift detection of a burst
  20. GRB060908: optical observations
  21. GRB 060729: An update on the late-time Swift observations
  22. GRB 060927: Spectroscopic redshift z=5.6
  23. IBAS Alert n.3501: not a GRB
  24. IBAS Alert n.3500: not a GRB
  25. GRB060923C: optical limit
  26. GRB060927: optical observations
  27. test of new software, grb
  28. GRB 060926: Swift-UVOT UVW1 Detection Retraction
  29. GRB 060927: pseudo-z from spectral parameters of the prompt emission
  30. GRB 060927: Swift/UVOT Optical Observations
  31. GRB 060927: Early color
  32. GRB 060927: Swift XRT Team refined analysis
  33. GRB 060927 optical limit
  34. GRB 060927, Swift-BAT refined analysis
  35. GRB 060927: Xinglong TNT optical observations
  36. GRB060926: improved redshift
  37. GRB 060927, optical observation
  38. GRB 060927: Possible host galaxy (star?) in the SDSS
  39. GRB 060927 : Kiso optical observation
  40. GRB060927: Faulkes Telescope South observation
  41. GRB 060926: MASTER: first minutes decay
  42. GRB060927 - SDSS Pre-Burst Observations
  43. GRB 060927: optical afterglow confirmation
  44. GRB 060927A: ROTSE-III Detection of Optical Counterpart
  45. Swift XRT boresight
  46. GRB 060927: Swift detection of a burst
  47. GRB060926: VLT redshift
  48. GRB 060926: Swift-UVOT Detections
  49. GRB 060923A: Schedule of Spitzer Space Telescope Observations
  50. GRB 060926: OPTIMA-Burst -- further observations
  51. GRB 060926: Swift XRT refined analysis
  52. GRB 060926, Swift-BAT refined analysis
  53. GRB 060923A: Radio Observations
  54. GRB 060926: MASTER OT alert observation
  55. GRB 060926: RTT150, UVOT afterglow candidate confirmation
  56. GRB 060912A: Redshift of probable host galaxy
  57. GRB 060926: BOOTES-IR observations
  58. GRB 060926: Watcher observations
  59. GRB060926 OPTIMA-Burst optical observation
  60. GRB 060926: MASTER optical observation
  61. GRB 060926: Swift detection of a burst
  62. GRB 060923C, Swift-BAT refined analysis
  63. GRB 060923C: VLA Observation
  64. GRB 060923C: NIR afterglow confirmed
  65. GRB060923C: AROMA optical obsevation
  66. GRB 060923C: Gemini Observations and Afterglow Candidate
  67. GRB 060923C, optical observation
  68. GRB 060923A: Gemini Second Epoch and Afterglow Confirmation
  69. GRB 060923C: VLT J-band observations
  70. GRB060923B: Swift/UVOT upper limits
  71. GRB 060923B: Swift XRT Refined Analysis
  72. GRB 060923C: Swift XRT refined analysis
  73. GRB 060923C, Swift-BAT partial refined analysis
  74. GRB 060923A: Swift XRT refined analysis
  75. GRB 060923C: Keck Observations
  76. GRB 060923A: Keck and Gemini Observations
  77. GRB 060923C: Xinglong TNT optical observations
  78. GRB 060923B, Swift-BAT refined analysis
  79. GRB060923C : Faulkes Telescope South optical limits
  80. GRB060923C: Faulkes Telescope North optical observations
  81. GRB 060923C: optical observation
  82. GRB 060923C: Swift detection of a burst
  83. GRB 060923B: Swift detection of a burst
  84. GRB 060923, Swift-BAT refined analysis
  85. GRB 060923: Early Super-LOTIS Observations
  86. GRB 060923: UKIRT nIR observations - candidate afterglow
  87. GRB060923: Faulkes Telescope North optical observations
  88. GRB060923 - SDSS Pre-Burst Observations
  89. GRB 060923: KAIT observations
  90. GRB 060923: Swift detection of a burst
  91. Swift detection of IGR J17497-2821 (trigger 230504)
  92. Swift detects a hard X-ray burst from AXP CXOU J164710.2-455216
  93. GRB060919: Swift/UVOT optical observations
  94. GRB 060919 : Faulkes South Telescope Observations
  95. GRB 060919, Swift-BAT refined analysis
  96. GRB060919: XRT refined analysis
  97. GRB 060919: TAROT optical observations
  98. GRB 060919: Swift detection of a burst
  99. GRB 060912A: VLA Observation
  100. GRB 060912A: Probable Host Galaxy

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