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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 060930: ROTSE-III Optical Limits
  2. GRB 060930: A long X-ray rich GRB detected by INTEGRAL
  3. GRB 060927 : GAO 150cm telescope optical observation
  4. GRB060929: Swift-XRT refined analysis.
  5. GRB 060929, Swift-BAT further refined analysis - late-time flare
  6. GRB 060929: TNG K-band observations
  7. GRB 060929, Swift-BAT refined analysis
  8. GRB060929: Optical limit
  9. GRB 060929: BART observation
  10. GRB 060929: MASTER-VWF-Kislovodsk observations
  11. GRB 060929: BOOTES-IR & OSN observations
  12. Liverpool Telescope observations of GRB 060929
  13. GRB 060929: Swift detection of a burst
  14. GRB060908: optical observations
  15. GRB 060729: An update on the late-time Swift observations
  16. GRB 060927: Spectroscopic redshift z=5.6
  17. IBAS Alert n.3501: not a GRB
  18. IBAS Alert n.3500: not a GRB
  19. GRB060923C: optical limit
  20. GRB060927: optical observations
  21. test of new software, grb
  22. GRB 060926: Swift-UVOT UVW1 Detection Retraction
  23. GRB 060927: pseudo-z from spectral parameters of the prompt emission
  24. GRB 060927: Swift/UVOT Optical Observations
  25. GRB 060927: Early color
  26. GRB 060927: Swift XRT Team refined analysis
  27. GRB 060927 optical limit
  28. GRB 060927, Swift-BAT refined analysis
  29. GRB 060927: Xinglong TNT optical observations
  30. GRB060926: improved redshift
  31. GRB 060927, optical observation
  32. GRB 060927: Possible host galaxy (star?) in the SDSS
  33. GRB 060927 : Kiso optical observation
  34. GRB060927: Faulkes Telescope South observation
  35. GRB 060926: MASTER: first minutes decay
  36. GRB060927 - SDSS Pre-Burst Observations
  37. GRB 060927: optical afterglow confirmation
  38. GRB 060927A: ROTSE-III Detection of Optical Counterpart
  39. Swift XRT boresight
  40. GRB 060927: Swift detection of a burst
  41. GRB060926: VLT redshift
  42. GRB 060926: Swift-UVOT Detections
  43. GRB 060923A: Schedule of Spitzer Space Telescope Observations
  44. GRB 060926: OPTIMA-Burst -- further observations
  45. GRB 060926: Swift XRT refined analysis
  46. GRB 060926, Swift-BAT refined analysis
  47. GRB 060923A: Radio Observations
  48. GRB 060926: MASTER OT alert observation
  49. GRB 060926: RTT150, UVOT afterglow candidate confirmation
  50. GRB 060912A: Redshift of probable host galaxy
  51. GRB 060926: BOOTES-IR observations
  52. GRB 060926: Watcher observations
  53. GRB060926 OPTIMA-Burst optical observation
  54. GRB 060926: MASTER optical observation
  55. GRB 060926: Swift detection of a burst
  56. GRB 060923C, Swift-BAT refined analysis
  57. GRB 060923C: VLA Observation
  58. GRB 060923C: NIR afterglow confirmed
  59. GRB060923C: AROMA optical obsevation
  60. GRB 060923C: Gemini Observations and Afterglow Candidate
  61. GRB 060923C, optical observation
  62. GRB 060923A: Gemini Second Epoch and Afterglow Confirmation
  63. GRB 060923C: VLT J-band observations
  64. GRB060923B: Swift/UVOT upper limits
  65. GRB 060923B: Swift XRT Refined Analysis
  66. GRB 060923C: Swift XRT refined analysis
  67. GRB 060923C, Swift-BAT partial refined analysis
  68. GRB 060923A: Swift XRT refined analysis
  69. GRB 060923C: Keck Observations
  70. GRB 060923A: Keck and Gemini Observations
  71. GRB 060923C: Xinglong TNT optical observations
  72. GRB 060923B, Swift-BAT refined analysis
  73. GRB060923C : Faulkes Telescope South optical limits
  74. GRB060923C: Faulkes Telescope North optical observations
  75. GRB 060923C: optical observation
  76. GRB 060923C: Swift detection of a burst
  77. GRB 060923B: Swift detection of a burst
  78. GRB 060923, Swift-BAT refined analysis
  79. GRB 060923: Early Super-LOTIS Observations
  80. GRB 060923: UKIRT nIR observations - candidate afterglow
  81. GRB060923: Faulkes Telescope North optical observations
  82. GRB060923 - SDSS Pre-Burst Observations
  83. GRB 060923: KAIT observations
  84. GRB 060923: Swift detection of a burst
  85. Swift detection of IGR J17497-2821 (trigger 230504)
  86. Swift detects a hard X-ray burst from AXP CXOU J164710.2-455216
  87. GRB060919: Swift/UVOT optical observations
  88. GRB 060919 : Faulkes South Telescope Observations
  89. GRB 060919, Swift-BAT refined analysis
  90. GRB060919: XRT refined analysis
  91. GRB 060919: TAROT optical observations
  92. GRB 060919: Swift detection of a burst
  93. GRB 060912A: VLA Observation
  94. GRB 060912A: Probable Host Galaxy
  95. IBAS Alert n.3470: not a GRB
  96. GRB060825: MAGIC telescope GeV observation
  97. Konus-Wind observation of GRB 060912
  98. IBAS Alert No.3468: not a GRB
  99. GRB 060912: Redshift of nearby 2MASS galaxy
  100. GRB060912: optical observations

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