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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 060929, Swift-BAT refined analysis
  2. GRB060929: Optical limit
  3. GRB 060929: BART observation
  4. GRB 060929: MASTER-VWF-Kislovodsk observations
  5. GRB 060929: BOOTES-IR & OSN observations
  6. Liverpool Telescope observations of GRB 060929
  7. GRB 060929: Swift detection of a burst
  8. GRB060908: optical observations
  9. GRB 060729: An update on the late-time Swift observations
  10. GRB 060927: Spectroscopic redshift z=5.6
  11. IBAS Alert n.3501: not a GRB
  12. IBAS Alert n.3500: not a GRB
  13. GRB060923C: optical limit
  14. GRB060927: optical observations
  15. test of new software, grb
  16. GRB 060926: Swift-UVOT UVW1 Detection Retraction
  17. GRB 060927: pseudo-z from spectral parameters of the prompt emission
  18. GRB 060927: Swift/UVOT Optical Observations
  19. GRB 060927: Early color
  20. GRB 060927: Swift XRT Team refined analysis
  21. GRB 060927 optical limit
  22. GRB 060927, Swift-BAT refined analysis
  23. GRB 060927: Xinglong TNT optical observations
  24. GRB060926: improved redshift
  25. GRB 060927, optical observation
  26. GRB 060927: Possible host galaxy (star?) in the SDSS
  27. GRB 060927 : Kiso optical observation
  28. GRB060927: Faulkes Telescope South observation
  29. GRB 060926: MASTER: first minutes decay
  30. GRB060927 - SDSS Pre-Burst Observations
  31. GRB 060927: optical afterglow confirmation
  32. GRB 060927A: ROTSE-III Detection of Optical Counterpart
  33. Swift XRT boresight
  34. GRB 060927: Swift detection of a burst
  35. GRB060926: VLT redshift
  36. GRB 060926: Swift-UVOT Detections
  37. GRB 060923A: Schedule of Spitzer Space Telescope Observations
  38. GRB 060926: OPTIMA-Burst -- further observations
  39. GRB 060926: Swift XRT refined analysis
  40. GRB 060926, Swift-BAT refined analysis
  41. GRB 060923A: Radio Observations
  42. GRB 060926: MASTER OT alert observation
  43. GRB 060926: RTT150, UVOT afterglow candidate confirmation
  44. GRB 060912A: Redshift of probable host galaxy
  45. GRB 060926: BOOTES-IR observations
  46. GRB 060926: Watcher observations
  47. GRB060926 OPTIMA-Burst optical observation
  48. GRB 060926: MASTER optical observation
  49. GRB 060926: Swift detection of a burst
  50. GRB 060923C, Swift-BAT refined analysis
  51. GRB 060923C: VLA Observation
  52. GRB 060923C: NIR afterglow confirmed
  53. GRB060923C: AROMA optical obsevation
  54. GRB 060923C: Gemini Observations and Afterglow Candidate
  55. GRB 060923C, optical observation
  56. GRB 060923A: Gemini Second Epoch and Afterglow Confirmation
  57. GRB 060923C: VLT J-band observations
  58. GRB060923B: Swift/UVOT upper limits
  59. GRB 060923B: Swift XRT Refined Analysis
  60. GRB 060923C: Swift XRT refined analysis
  61. GRB 060923C, Swift-BAT partial refined analysis
  62. GRB 060923A: Swift XRT refined analysis
  63. GRB 060923C: Keck Observations
  64. GRB 060923A: Keck and Gemini Observations
  65. GRB 060923C: Xinglong TNT optical observations
  66. GRB 060923B, Swift-BAT refined analysis
  67. GRB060923C : Faulkes Telescope South optical limits
  68. GRB060923C: Faulkes Telescope North optical observations
  69. GRB 060923C: optical observation
  70. GRB 060923C: Swift detection of a burst
  71. GRB 060923B: Swift detection of a burst
  72. GRB 060923, Swift-BAT refined analysis
  73. GRB 060923: Early Super-LOTIS Observations
  74. GRB 060923: UKIRT nIR observations - candidate afterglow
  75. GRB060923: Faulkes Telescope North optical observations
  76. GRB060923 - SDSS Pre-Burst Observations
  77. GRB 060923: KAIT observations
  78. GRB 060923: Swift detection of a burst
  79. Swift detection of IGR J17497-2821 (trigger 230504)
  80. Swift detects a hard X-ray burst from AXP CXOU J164710.2-455216
  81. GRB060919: Swift/UVOT optical observations
  82. GRB 060919 : Faulkes South Telescope Observations
  83. GRB 060919, Swift-BAT refined analysis
  84. GRB060919: XRT refined analysis
  85. GRB 060919: TAROT optical observations
  86. GRB 060919: Swift detection of a burst
  87. GRB 060912A: VLA Observation
  88. GRB 060912A: Probable Host Galaxy
  89. IBAS Alert n.3470: not a GRB
  90. GRB060825: MAGIC telescope GeV observation
  91. Konus-Wind observation of GRB 060912
  92. IBAS Alert No.3468: not a GRB
  93. GRB 060912: Redshift of nearby 2MASS galaxy
  94. GRB060912: optical observations
  95. GRB 060912B: Watcher observations
  96. GRB060912: Swift/UVOT Observations
  97. GRB060912: OPTIMA-Burst optical observations
  98. GRB 060912B: a long GRB detected with INTEGRAL
  99. GRB 060912: Swift XRT Team Refined Analysis
  100. GRB 060912, Swift-BAT refined analysis

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