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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. GRB060923C: optical limit
  2. GRB060927: optical observations
  3. test of new software, grb
  4. GRB 060926: Swift-UVOT UVW1 Detection Retraction
  5. GRB 060927: pseudo-z from spectral parameters of the prompt emission
  6. GRB 060927: Swift/UVOT Optical Observations
  7. GRB 060927: Early color
  8. GRB 060927: Swift XRT Team refined analysis
  9. GRB 060927 optical limit
  10. GRB 060927, Swift-BAT refined analysis
  11. GRB 060927: Xinglong TNT optical observations
  12. GRB060926: improved redshift
  13. GRB 060927, optical observation
  14. GRB 060927: Possible host galaxy (star?) in the SDSS
  15. GRB 060927 : Kiso optical observation
  16. GRB060927: Faulkes Telescope South observation
  17. GRB 060926: MASTER: first minutes decay
  18. GRB060927 - SDSS Pre-Burst Observations
  19. GRB 060927: optical afterglow confirmation
  20. GRB 060927A: ROTSE-III Detection of Optical Counterpart
  21. Swift XRT boresight
  22. GRB 060927: Swift detection of a burst
  23. GRB060926: VLT redshift
  24. GRB 060926: Swift-UVOT Detections
  25. GRB 060923A: Schedule of Spitzer Space Telescope Observations
  26. GRB 060926: OPTIMA-Burst -- further observations
  27. GRB 060926: Swift XRT refined analysis
  28. GRB 060926, Swift-BAT refined analysis
  29. GRB 060923A: Radio Observations
  30. GRB 060926: MASTER OT alert observation
  31. GRB 060926: RTT150, UVOT afterglow candidate confirmation
  32. GRB 060912A: Redshift of probable host galaxy
  33. GRB 060926: BOOTES-IR observations
  34. GRB 060926: Watcher observations
  35. GRB060926 OPTIMA-Burst optical observation
  36. GRB 060926: MASTER optical observation
  37. GRB 060926: Swift detection of a burst
  38. GRB 060923C, Swift-BAT refined analysis
  39. GRB 060923C: VLA Observation
  40. GRB 060923C: NIR afterglow confirmed
  41. GRB060923C: AROMA optical obsevation
  42. GRB 060923C: Gemini Observations and Afterglow Candidate
  43. GRB 060923C, optical observation
  44. GRB 060923A: Gemini Second Epoch and Afterglow Confirmation
  45. GRB 060923C: VLT J-band observations
  46. GRB060923B: Swift/UVOT upper limits
  47. GRB 060923B: Swift XRT Refined Analysis
  48. GRB 060923C: Swift XRT refined analysis
  49. GRB 060923C, Swift-BAT partial refined analysis
  50. GRB 060923A: Swift XRT refined analysis
  51. GRB 060923C: Keck Observations
  52. GRB 060923A: Keck and Gemini Observations
  53. GRB 060923C: Xinglong TNT optical observations
  54. GRB 060923B, Swift-BAT refined analysis
  55. GRB060923C : Faulkes Telescope South optical limits
  56. GRB060923C: Faulkes Telescope North optical observations
  57. GRB 060923C: optical observation
  58. GRB 060923C: Swift detection of a burst
  59. GRB 060923B: Swift detection of a burst
  60. GRB 060923, Swift-BAT refined analysis
  61. GRB 060923: Early Super-LOTIS Observations
  62. GRB 060923: UKIRT nIR observations - candidate afterglow
  63. GRB060923: Faulkes Telescope North optical observations
  64. GRB060923 - SDSS Pre-Burst Observations
  65. GRB 060923: KAIT observations
  66. GRB 060923: Swift detection of a burst
  67. Swift detection of IGR J17497-2821 (trigger 230504)
  68. Swift detects a hard X-ray burst from AXP CXOU J164710.2-455216
  69. GRB060919: Swift/UVOT optical observations
  70. GRB 060919 : Faulkes South Telescope Observations
  71. GRB 060919, Swift-BAT refined analysis
  72. GRB060919: XRT refined analysis
  73. GRB 060919: TAROT optical observations
  74. GRB 060919: Swift detection of a burst
  75. GRB 060912A: VLA Observation
  76. GRB 060912A: Probable Host Galaxy
  77. IBAS Alert n.3470: not a GRB
  78. GRB060825: MAGIC telescope GeV observation
  79. Konus-Wind observation of GRB 060912
  80. IBAS Alert No.3468: not a GRB
  81. GRB 060912: Redshift of nearby 2MASS galaxy
  82. GRB060912: optical observations
  83. GRB 060912B: Watcher observations
  84. GRB060912: Swift/UVOT Observations
  85. GRB060912: OPTIMA-Burst optical observations
  86. GRB 060912B: a long GRB detected with INTEGRAL
  87. GRB 060912: Swift XRT Team Refined Analysis
  88. GRB 060912, Swift-BAT refined analysis
  89. GRB 060912: Correction to GCN 5559
  90. GRB 060912: Xinglong TNT optical observations
  91. GRB 060912: Swift detection of a burst with an optical afterglow
  92. GRB060906: Danish/DFOSC optical observations
  93. VLA observations of GRB 060908
  94. GRB 060908: redshift
  95. GRB 060908, Swift/XRT refined analysis
  96. GRB 060908: Swift/UVOT Observations
  97. GRB 060908: Danish/DFOSC optical observations
  98. GRB 060908, Swift-BAT refined analysis
  99. GRB 060908 - SDSS Pre-burst Observations
  100. GRB 060904B : CFHT/WIRCam NIR afterglow observations

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