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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"

43601 results found.

  1. GRB050916 : Swift-XRT refined analysis
  2. GRB 050916: XRT position
  3. GRB 050915b, SMARTS optical/IR observations of the XRT position
  4. GRB 050915B: Swift-BAT refined analysis
  5. GRB 050915B: Swift/UVOT Upper Limits
  6. GRB050916: Swift-BAT detection of a long weak burst
  7. GRB 050915a: IR Transient
  8. GRB 050915B: XRT position
  9. GRB 050915b, SMARTS optical/IR observations
  10. GRB050915B: Swift-BAT detection of a long bright burst
  11. GRB050915: Swift/UVOT upper limits
  12. GRB 050915: KAIT optical limit
  13. GRB 050915: IR Observations
  14. GRB 050915: Swift XRT refined analysis
  15. GRB 050915: Swift-BAT refined analysis
  16. GRB050915: P60 Optical Observations
  17. GRB050915, optical observations
  18. GRB050915: XRT position
  19. GRB 050915: ROTSE-III optical limits
  20. GRB 050915: Swift detection of a GRB
  21. GRB050911: Upper limit on X-ray afterglow
  22. Swift-BAT trigger 155072 ground analysis
  23. Swift-BAT trigger 155072 is probably not a GRB
  24. GRB050914: XRT position probably due to cosmic ray
  25. GRB 050911: LCO limits on a variable source
  26. GRB 050908: DEIMOS spectrum and further analysis
  27. Swift is in normal operation
  28. GRB050911: Swift UVOT followup observations
  29. GRB 050911, optical content of Swift/XRT error box
  30. GRB050911: Swift-XRT position
  31. GRB 050911: LCO observations
  32. GRB 050911, optical observations
  33. GRB 050911: Swift-BAT refined analysis
  34. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  35. GRB 050911: z~0.16 cluster in the field
  36. GRB050911: Swift-BAT detection of a long burst
  37. GRB050908: detection of Swift/UVOT optical counterpart
  38. GRB 050910a: TAROT early optical limits
  39. RBO GRB 050908 observations
  40. WIRO observations in I of GRB 050908
  41. GRB 050906: Possible X-ray Counterpart
  42. GRB 050906: RTT150 optical observations
  43. GRB050908: Swift/UVOT Early upper limits
  44. GRB050908: VLT R-band decay index.
  45. GRB050908 : Swift-XRT refined analysis
  46. GRB 050908: Swift-BAT refined analysis
  47. GRB 050908: Optical observations
  48. Gemini Spectroscopy of GRB 050908
  49. GRB 050908: spectroscopic redshift
  50. GRB 050908: Prompt PROMPT Observations
  51. GRB 050908 : Swift XRT position
  52. GRB 050908: KAIT observations
  53. GRB 050908: P60 Confirmation of Optical Afterglow
  54. GRB 050908: Optical Observations
  55. GRB 050908: Swift detection of a burst
  56. Swift trigger 154073 is not a GRB
  57. GRB 050906: Optical observations at the Very Large Telescope
  58. GRB 050904 BAT refined analysis of complete data set
  59. GRB 050906: MARGE Optical Limits
  60. GRB 050906: Swift-BAT refined analysis
  61. GRB 050906: Swift XRT upper limit
  62. GRB 050906: Radio Observations
  63. GRB 050904: Keck I-band Imaging
  64. GRB050906: P60 Observations
  65. GRB 050904: more VLT NIR observations
  66. GRB 050904: BOOTES early R-band observation
  67. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  68. GRB 050906: Bright galaxy in BAT error box
  69. GRB 050906: Swift/BAT Detection of a possible burst
  70. GRB 050904: More SOAR
  71. GRB 050904: photometric redshift
  72. GRB 050904: Swift/UVOT observations
  73. GRB 050904: Afterglow Astrometry
  74. GRB 050904: NIR object inside the XRT error box
  75. GRB 050904: early Swift XRT analysis results
  76. GRB 050904: SOAR YJ and PROMPT Ic Observations
  77. GRB 050904: BAT refined analysis of partial data set
  78. GRB 050904: TAROT optical measurements
  79. GRB050904: Optical Observations
  80. GRB 050904: Environmental Constraints
  81. GRB 050904: Possible High-Redshift GRB
  82. GRB 050904: SOAR/PROMPT Observations
  83. GRB050904: P60 Observations
  84. GRB 050904: TAROT optical limits
  85. GRB050904: Swift-BAT detection of a probable burst
  86. Swift-BAT triggers 153461-153465 are not GRBs
  87. Retraction of Swift-BAT trigger #153355
  88. GRB 050824: MDM Observations
  89. GRB 050827: Swift XRT preliminary analysis results
  90. IBAS Alerts 2641 and 2642: not a real GRB
  91. Swift Trigger #152652 is not a GRB
  92. GRB 050827 : OSN 1.5m optical observations
  93. GRB 050827: P200 NIR Observations
  94. GRB050827: Swift/UVOT upper limits
  95. GRB 050827: Optical Limit
  96. GRB 050827: XRT possible afterglow detection
  97. GRB050824: Maidanak optical limits
  98. GRB050820A: RTT150 optical observations
  99. GRB050827: RTT150 optical observations
  100. GRB 050827: Swift-BAT refined analysis

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