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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. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  2. GRB 050911: z~0.16 cluster in the field
  3. GRB050911: Swift-BAT detection of a long burst
  4. GRB050908: detection of Swift/UVOT optical counterpart
  5. GRB 050910a: TAROT early optical limits
  6. RBO GRB 050908 observations
  7. WIRO observations in I of GRB 050908
  8. GRB 050906: Possible X-ray Counterpart
  9. GRB 050906: RTT150 optical observations
  10. GRB050908: Swift/UVOT Early upper limits
  11. GRB050908: VLT R-band decay index.
  12. GRB050908 : Swift-XRT refined analysis
  13. GRB 050908: Swift-BAT refined analysis
  14. GRB 050908: Optical observations
  15. Gemini Spectroscopy of GRB 050908
  16. GRB 050908: spectroscopic redshift
  17. GRB 050908: Prompt PROMPT Observations
  18. GRB 050908 : Swift XRT position
  19. GRB 050908: KAIT observations
  20. GRB 050908: P60 Confirmation of Optical Afterglow
  21. GRB 050908: Optical Observations
  22. GRB 050908: Swift detection of a burst
  23. Swift trigger 154073 is not a GRB
  24. GRB 050906: Optical observations at the Very Large Telescope
  25. GRB050904: CrAO optical observations
  26. GRB 050904 BAT refined analysis of complete data set
  27. GRB 050904: Subaru Optical Spectroscopy
  28. GRB 050906: MARGE Optical Limits
  29. GRB 050906: Swift-BAT refined analysis
  30. GRB 050906: Swift XRT upper limit
  31. GRB 050906: Radio Observations
  32. GRB 050904: Keck I-band Imaging
  33. GRB050906: P60 Observations
  34. GRB 050904: more VLT NIR observations
  35. GRB 050904: BOOTES early R-band observation
  36. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  37. GRB 050906: Bright galaxy in BAT error box
  38. GRB 050906: Swift/BAT Detection of a possible burst
  39. GRB 050904: More SOAR
  40. GRB 050904: photometric redshift
  41. GRB 050904: Swift/UVOT observations
  42. GRB 050904: Afterglow Astrometry
  43. GRB 050904: NIR object inside the XRT error box
  44. GRB 050904: early Swift XRT analysis results
  45. GRB 050904: SOAR YJ and PROMPT Ic Observations
  46. GRB 050904: BAT refined analysis of partial data set
  47. GRB 050904: TAROT optical measurements
  48. GRB050904: Optical Observations
  49. GRB 050904: Environmental Constraints
  50. GRB 050904: Possible High-Redshift GRB
  51. GRB 050904: SOAR/PROMPT Observations
  52. GRB050904: P60 Observations
  53. GRB 050904: TAROT optical limits
  54. GRB050904: Swift-BAT detection of a probable burst
  55. Swift-BAT triggers 153461-153465 are not GRBs
  56. Retraction of Swift-BAT trigger #153355
  57. GRB 050824: MDM Observations
  58. GRB 050827: Swift XRT preliminary analysis results
  59. IBAS Alerts 2641 and 2642: not a real GRB
  60. Swift Trigger #152652 is not a GRB
  61. GRB 050827 : OSN 1.5m optical observations
  62. GRB 050827: P200 NIR Observations
  63. GRB050827: Swift/UVOT upper limits
  64. GRB 050827: Optical Limit
  65. GRB 050827: XRT possible afterglow detection
  66. GRB 050826 : Lulin R band observation
  67. GRB050824: Maidanak optical limits
  68. GRB050820A: RTT150 optical observations
  69. GRB050827: RTT150 optical observations
  70. GRB 050827: Swift-BAT refined analysis
  71. GRB050827: Swift-BAT detection of a burst
  72. Subaru Observations of GRB050724
  73. GRB 050826: Optical Candidate
  74. GRB050824, HETE-2 Observation
  75. GRB 050826: Swift XRT preliminary analysis results
  76. GRB 050826: BAT refined analysis
  77. GRB050826: Swift/UVOT early upper limits
  78. GRB050824: First 2 hours of power low optical decay?
  79. GRB 050826: Swift XRT position
  80. GRB050826: Swift-BAT detection of a long burst
  81. GRB050824: MASTER final analysis of the OT observations
  82. Possible GRB050825:MASTER optical observations
  83. Swift-BAT trigger 152038 is definitely not a GRB
  84. GRB050824: CORRECTION to UVOT observing times
  85. Swift-BAT trigger 152038 is probably not a GRB
  86. GRB050824: Swift/UVOT detection of fading afterglow
  87. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  88. GRB050824, I-band imaging
  89. GRB050824: Radio Observations
  90. GRB 050824: Spectroscopic redshift from the VLT
  91. GRB 050822: refined XRT analysis
  92. GRB 050824: XRT refined analysis and possible afterglow detection
  93. GRB 050824: BAT refined analysis of a soft weak burst
  94. GRB050824: MASTER:OT decay
  95. GRB050824: MASTER observation OT
  96. GRB050805a: MASTER optical candidat
  97. GRB 050824: ROTSE-III Optical Limits
  98. GRB050824: Swift-BAT detection of a burst
  99. GRB 050824 optical candidate
  100. GRB050820A: RTT150 optical observations

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