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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"

19532 results found.

  1. GRB 050915: Swift-BAT refined analysis
  2. GRB050915, optical observations
  3. GRB050915: XRT position
  4. GRB 050915: ROTSE-III optical limits
  5. GRB 050915: Swift detection of a GRB
  6. GRB050911: Upper limit on X-ray afterglow
  7. Swift-BAT trigger 155072 ground analysis
  8. Swift-BAT trigger 155072 is probably not a GRB
  9. GRB050914: XRT position probably due to cosmic ray
  10. Swift is in normal operation
  11. GRB050911: Swift UVOT followup observations
  12. GRB 050911, optical content of Swift/XRT error box
  13. GRB050911: Swift-XRT position
  14. GRB 050911, optical observations
  15. GRB 050911: Swift-BAT refined analysis
  16. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  17. GRB050911: Swift-BAT detection of a long burst
  18. GRB050908: detection of Swift/UVOT optical counterpart
  19. RBO GRB 050908 observations
  20. WIRO observations in I of GRB 050908
  21. GRB 050906: Possible X-ray Counterpart
  22. GRB050908: Swift/UVOT Early upper limits
  23. GRB050908 : Swift-XRT refined analysis
  24. GRB 050908: Swift-BAT refined analysis
  25. GRB 050908: Optical observations
  26. Gemini Spectroscopy of GRB 050908
  27. GRB 050908 : Swift XRT position
  28. GRB 050908: KAIT observations
  29. GRB 050908: P60 Confirmation of Optical Afterglow
  30. GRB 050908: Swift detection of a burst
  31. Swift trigger 154073 is not a GRB
  32. GRB050904: CrAO optical observations
  33. GRB 050904 BAT refined analysis of complete data set
  34. GRB 050906: MARGE Optical Limits
  35. GRB 050906: Swift-BAT refined analysis
  36. GRB 050906: Swift XRT upper limit
  37. GRB050906: P60 Observations
  38. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  39. GRB 050906: Bright galaxy in BAT error box
  40. GRB 050906: Swift/BAT Detection of a possible burst
  41. GRB 050904: Swift/UVOT observations
  42. GRB 050904: early Swift XRT analysis results
  43. GRB 050904: BAT refined analysis of partial data set
  44. GRB050904: P60 Observations
  45. GRB 050904: TAROT optical limits
  46. GRB050904: Swift-BAT detection of a probable burst
  47. Swift-BAT triggers 153461-153465 are not GRBs
  48. Retraction of Swift-BAT trigger #153355
  49. GRB 050824: MDM Observations
  50. GRB 050827: Swift XRT preliminary analysis results
  51. Swift Trigger #152652 is not a GRB
  52. GRB050827: Swift/UVOT upper limits
  53. GRB 050827: Optical Limit
  54. GRB 050827: XRT possible afterglow detection
  55. GRB050827: RTT150 optical observations
  56. GRB 050827: Swift-BAT refined analysis
  57. GRB050827: Swift-BAT detection of a burst
  58. GRB 050826: Optical Candidate
  59. GRB050824, HETE-2 Observation
  60. GRB 050826: Swift XRT preliminary analysis results
  61. GRB 050826: BAT refined analysis
  62. GRB050826: Swift/UVOT early upper limits
  63. GRB050824: First 2 hours of power low optical decay?
  64. GRB 050826: Swift XRT position
  65. GRB050826: Swift-BAT detection of a long burst
  66. GRB050824: MASTER final analysis of the OT observations
  67. Possible GRB050825:MASTER optical observations
  68. Swift-BAT trigger 152038 is definitely not a GRB
  69. GRB050824: CORRECTION to UVOT observing times
  70. Swift-BAT trigger 152038 is probably not a GRB
  71. GRB050824: Swift/UVOT detection of fading afterglow
  72. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  73. GRB050824, I-band imaging
  74. GRB 050822: refined XRT analysis
  75. GRB 050824: XRT refined analysis and possible afterglow detection
  76. GRB 050824: BAT refined analysis of a soft weak burst
  77. GRB050824: MASTER:OT decay
  78. GRB050824: MASTER observation OT
  79. GRB050805a: MASTER optical candidat
  80. GRB 050824: ROTSE-III Optical Limits
  81. GRB050824: Swift-BAT detection of a burst
  82. GRB050822: Swift/UVOT upper limits
  83. GRB 050820A BAT observations of second, larger episode of emission
  84. GRB 050822: Swift-BAT refined analysis
  85. GRB 050820a - corrections to GCN 3846
  86. Swift/UVOT UV Photometry of GRB 050820B
  87. GRB 050822: ROTSE-III Prompt Optical Limits
  88. GRB 050822: Swift detection of a long burst
  89. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  90. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  91. GRB050820a BVRcIc field photometry
  92. GRB050820B XMM-Newton observation
  93. GRB 050820a: NIR Observations by WIRO
  94. GRB 050820B: Swift XRT position
  95. GRB050820B: Refined analysis of the Swift-BAT burst
  96. GRB050820B: BAT-Swift detection of a bright GRB
  97. Swift/UVOT photometry of GRB050820
  98. GRB050820: refined XRT analysis
  99. GRB 050820: Early RAPTOR detections
  100. GRB 050820 Swift-BAT refined analysis

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