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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"

43590 results found.

  1. GRB 050915: KAIT optical limit
  2. GRB 050915: IR Observations
  3. GRB 050915: Swift XRT refined analysis
  4. GRB 050915: Swift-BAT refined analysis
  5. GRB050915: P60 Optical Observations
  6. GRB050915, optical observations
  7. GRB050915: XRT position
  8. GRB 050915: ROTSE-III optical limits
  9. GRB 050915: Swift detection of a GRB
  10. GRB050911: Upper limit on X-ray afterglow
  11. Swift-BAT trigger 155072 ground analysis
  12. Swift-BAT trigger 155072 is probably not a GRB
  13. GRB050914: XRT position probably due to cosmic ray
  14. GRB 050911: LCO limits on a variable source
  15. GRB 050908: DEIMOS spectrum and further analysis
  16. Swift is in normal operation
  17. GRB050911: Swift UVOT followup observations
  18. GRB 050911, optical content of Swift/XRT error box
  19. GRB050911: Swift-XRT position
  20. GRB 050911: LCO observations
  21. GRB 050911, optical observations
  22. GRB 050911: Swift-BAT refined analysis
  23. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  24. GRB 050911: z~0.16 cluster in the field
  25. GRB050911: Swift-BAT detection of a long burst
  26. GRB050908: detection of Swift/UVOT optical counterpart
  27. GRB 050910a: TAROT early optical limits
  28. RBO GRB 050908 observations
  29. WIRO observations in I of GRB 050908
  30. GRB 050906: Possible X-ray Counterpart
  31. GRB 050906: RTT150 optical observations
  32. GRB050908: Swift/UVOT Early upper limits
  33. GRB050908: VLT R-band decay index.
  34. GRB050908 : Swift-XRT refined analysis
  35. GRB 050908: Swift-BAT refined analysis
  36. GRB 050908: Optical observations
  37. Gemini Spectroscopy of GRB 050908
  38. GRB 050908: spectroscopic redshift
  39. GRB 050908: Prompt PROMPT Observations
  40. GRB 050908 : Swift XRT position
  41. GRB 050908: KAIT observations
  42. GRB 050908: P60 Confirmation of Optical Afterglow
  43. GRB 050908: Optical Observations
  44. GRB 050908: Swift detection of a burst
  45. Swift trigger 154073 is not a GRB
  46. GRB 050906: Optical observations at the Very Large Telescope
  47. GRB 050904 BAT refined analysis of complete data set
  48. GRB 050906: MARGE Optical Limits
  49. GRB 050906: Swift-BAT refined analysis
  50. GRB 050906: Swift XRT upper limit
  51. GRB 050906: Radio Observations
  52. GRB 050904: Keck I-band Imaging
  53. GRB050906: P60 Observations
  54. GRB 050904: more VLT NIR observations
  55. GRB 050904: BOOTES early R-band observation
  56. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  57. GRB 050906: Bright galaxy in BAT error box
  58. GRB 050906: Swift/BAT Detection of a possible burst
  59. GRB 050904: More SOAR
  60. GRB 050904: photometric redshift
  61. GRB 050904: Swift/UVOT observations
  62. GRB 050904: Afterglow Astrometry
  63. GRB 050904: NIR object inside the XRT error box
  64. GRB 050904: early Swift XRT analysis results
  65. GRB 050904: SOAR YJ and PROMPT Ic Observations
  66. GRB 050904: BAT refined analysis of partial data set
  67. GRB 050904: TAROT optical measurements
  68. GRB050904: Optical Observations
  69. GRB 050904: Environmental Constraints
  70. GRB 050904: Possible High-Redshift GRB
  71. GRB 050904: SOAR/PROMPT Observations
  72. GRB050904: P60 Observations
  73. GRB 050904: TAROT optical limits
  74. GRB050904: Swift-BAT detection of a probable burst
  75. Swift-BAT triggers 153461-153465 are not GRBs
  76. Retraction of Swift-BAT trigger #153355
  77. GRB 050824: MDM Observations
  78. GRB 050827: Swift XRT preliminary analysis results
  79. IBAS Alerts 2641 and 2642: not a real GRB
  80. Swift Trigger #152652 is not a GRB
  81. GRB 050827 : OSN 1.5m optical observations
  82. GRB 050827: P200 NIR Observations
  83. GRB050827: Swift/UVOT upper limits
  84. GRB 050827: Optical Limit
  85. GRB 050827: XRT possible afterglow detection
  86. GRB050824: Maidanak optical limits
  87. GRB050820A: RTT150 optical observations
  88. GRB050827: RTT150 optical observations
  89. GRB 050827: Swift-BAT refined analysis
  90. GRB050827: Swift-BAT detection of a burst
  91. Subaru Observations of GRB050724
  92. GRB 050826: Optical Candidate
  93. GRB050824, HETE-2 Observation
  94. GRB 050826: Swift XRT preliminary analysis results
  95. GRB 050826: BAT refined analysis
  96. GRB050826: Swift/UVOT early upper limits
  97. GRB050824: First 2 hours of power low optical decay?
  98. GRB 050826: Swift XRT position
  99. GRB050826: Swift-BAT detection of a long burst
  100. GRB050824: MASTER final analysis of the OT observations

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