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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. GRB061002: Swift UVOT followup observations
  2. GRB 060930: near-IR afterglow candidate
  3. GRB 061002: Swift-XRT Team Refined Analysis
  4. VLA observations of GRB 060926
  5. GRB061002 - SDSS Pre-Burst Observations
  6. GRB 061002, Swift-BAT refined analysis
  7. GRB061002: MASTER-VWF-Kislovodsk observations
  8. GRB 061002: Swift detection of a burst: CORRECTED CONTENT
  9. GRB 061002: Swift detection of a burst
  10. GRB 060908: Detection of a possible host
  11. GRB 060923A: Probable host galaxy in the R-band
  12. GRB 060807: Detection of a possible host galaxy
  13. GRB 060923A: VLA K-band Observations
  14. GRB060930: Faulkes Telescope South observation
  15. GRB 060930: Xinglong TNT optical observations
  16. GRB 060929: Further XRT Refined Analysis
  17. GRB 060929: Swift/UVOT Optical Observations
  18. GRB 060930: ROTSE-III Optical Limits
  19. GRB 060930: A long X-ray rich GRB detected by INTEGRAL
  20. GRB 060927 : GAO 150cm telescope optical observation
  21. GRB060929: Swift-XRT refined analysis.
  22. GRB 060929, Swift-BAT further refined analysis - late-time flare
  23. GRB 060929: TNG K-band observations
  24. GRB 060929, Swift-BAT refined analysis
  25. GRB060929: Optical limit
  26. GRB 060929: BART observation
  27. GRB 060929: MASTER-VWF-Kislovodsk observations
  28. GRB 060929: BOOTES-IR & OSN observations
  29. Liverpool Telescope observations of GRB 060929
  30. GRB 060929: Swift detection of a burst
  31. GRB060908: optical observations
  32. GRB 060729: An update on the late-time Swift observations
  33. GRB 060927: Spectroscopic redshift z=5.6
  34. IBAS Alert n.3501: not a GRB
  35. IBAS Alert n.3500: not a GRB
  36. GRB060923C: optical limit
  37. GRB060927: optical observations
  38. test of new software, grb
  39. GRB 060926: Swift-UVOT UVW1 Detection Retraction
  40. GRB 060927: pseudo-z from spectral parameters of the prompt emission
  41. GRB 060927: Swift/UVOT Optical Observations
  42. GRB 060927: Early color
  43. GRB 060927: Swift XRT Team refined analysis
  44. GRB 060927 optical limit
  45. GRB 060927, Swift-BAT refined analysis
  46. GRB 060927: Xinglong TNT optical observations
  47. GRB060926: improved redshift
  48. GRB 060927, optical observation
  49. GRB 060927: Possible host galaxy (star?) in the SDSS
  50. GRB 060927 : Kiso optical observation
  51. GRB060927: Faulkes Telescope South observation
  52. GRB 060926: MASTER: first minutes decay
  53. GRB060927 - SDSS Pre-Burst Observations
  54. GRB 060927: optical afterglow confirmation
  55. GRB 060927A: ROTSE-III Detection of Optical Counterpart
  56. Swift XRT boresight
  57. GRB 060927: Swift detection of a burst
  58. GRB060926: VLT redshift
  59. GRB 060926: Swift-UVOT Detections
  60. GRB 060923A: Schedule of Spitzer Space Telescope Observations
  61. GRB 060926: OPTIMA-Burst -- further observations
  62. GRB 060926: Swift XRT refined analysis
  63. GRB 060926, Swift-BAT refined analysis
  64. GRB 060923A: Radio Observations
  65. GRB 060926: MASTER OT alert observation
  66. GRB 060926: RTT150, UVOT afterglow candidate confirmation
  67. GRB 060912A: Redshift of probable host galaxy
  68. GRB 060926: BOOTES-IR observations
  69. GRB 060926: Watcher observations
  70. GRB060926 OPTIMA-Burst optical observation
  71. GRB 060926: MASTER optical observation
  72. GRB 060926: Swift detection of a burst
  73. GRB 060923C, Swift-BAT refined analysis
  74. GRB 060923C: VLA Observation
  75. GRB 060923C: NIR afterglow confirmed
  76. GRB060923C: AROMA optical obsevation
  77. GRB 060923C: Gemini Observations and Afterglow Candidate
  78. GRB 060923C, optical observation
  79. GRB 060923A: Gemini Second Epoch and Afterglow Confirmation
  80. GRB 060923C: VLT J-band observations
  81. GRB060923B: Swift/UVOT upper limits
  82. GRB 060923B: Swift XRT Refined Analysis
  83. GRB 060923C: Swift XRT refined analysis
  84. GRB 060923C, Swift-BAT partial refined analysis
  85. GRB 060923A: Swift XRT refined analysis
  86. GRB 060923C: Keck Observations
  87. GRB 060923A: Keck and Gemini Observations
  88. GRB 060923C: Xinglong TNT optical observations
  89. GRB 060923B, Swift-BAT refined analysis
  90. GRB060923C : Faulkes Telescope South optical limits
  91. GRB060923C: Faulkes Telescope North optical observations
  92. GRB 060923C: optical observation
  93. GRB 060923C: Swift detection of a burst
  94. GRB 060923B: Swift detection of a burst
  95. GRB 060923, Swift-BAT refined analysis
  96. GRB 060923: Early Super-LOTIS Observations
  97. GRB 060923: UKIRT nIR observations - candidate afterglow
  98. GRB060923: Faulkes Telescope North optical observations
  99. GRB060923 - SDSS Pre-Burst Observations
  100. GRB 060923: KAIT observations

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