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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"

26042 results found.

  1. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  2. GRB050911: Swift-BAT detection of a long burst
  3. GRB050908: detection of Swift/UVOT optical counterpart
  4. GRB 050910a: TAROT early optical limits
  5. RBO GRB 050908 observations
  6. WIRO observations in I of GRB 050908
  7. GRB 050906: Possible X-ray Counterpart
  8. GRB050908: Swift/UVOT Early upper limits
  9. GRB050908: VLT R-band decay index.
  10. GRB050908 : Swift-XRT refined analysis
  11. GRB 050908: Swift-BAT refined analysis
  12. GRB 050908: Optical observations
  13. Gemini Spectroscopy of GRB 050908
  14. GRB 050908: spectroscopic redshift
  15. GRB 050908: Prompt PROMPT Observations
  16. GRB 050908 : Swift XRT position
  17. GRB 050908: KAIT observations
  18. GRB 050908: P60 Confirmation of Optical Afterglow
  19. GRB 050908: Swift detection of a burst
  20. Swift trigger 154073 is not a GRB
  21. GRB050904: CrAO optical observations
  22. GRB 050904 BAT refined analysis of complete data set
  23. GRB 050904: Subaru Optical Spectroscopy
  24. GRB 050906: MARGE Optical Limits
  25. GRB 050906: Swift-BAT refined analysis
  26. GRB 050906: Swift XRT upper limit
  27. GRB 050904: Keck I-band Imaging
  28. GRB050906: P60 Observations
  29. GRB 050904: more VLT NIR observations
  30. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  31. GRB 050906: Bright galaxy in BAT error box
  32. GRB 050906: Swift/BAT Detection of a possible burst
  33. GRB 050904: More SOAR
  34. GRB 050904: photometric redshift
  35. GRB 050904: Swift/UVOT observations
  36. GRB 050904: Afterglow Astrometry
  37. GRB 050904: NIR object inside the XRT error box
  38. GRB 050904: early Swift XRT analysis results
  39. GRB 050904: SOAR YJ and PROMPT Ic Observations
  40. GRB 050904: BAT refined analysis of partial data set
  41. GRB050904: Optical Observations
  42. GRB 050904: Environmental Constraints
  43. GRB 050904: Possible High-Redshift GRB
  44. GRB 050904: SOAR/PROMPT Observations
  45. GRB050904: P60 Observations
  46. GRB 050904: TAROT optical limits
  47. GRB050904: Swift-BAT detection of a probable burst
  48. Swift-BAT triggers 153461-153465 are not GRBs
  49. Retraction of Swift-BAT trigger #153355
  50. GRB 050824: MDM Observations
  51. GRB 050827: Swift XRT preliminary analysis results
  52. Swift Trigger #152652 is not a GRB
  53. GRB 050827 : OSN 1.5m optical observations
  54. GRB 050827: P200 NIR Observations
  55. GRB050827: Swift/UVOT upper limits
  56. GRB 050827: Optical Limit
  57. GRB 050827: XRT possible afterglow detection
  58. GRB 050826 : Lulin R band observation
  59. GRB050827: RTT150 optical observations
  60. GRB 050827: Swift-BAT refined analysis
  61. GRB050827: Swift-BAT detection of a burst
  62. GRB 050826: Optical Candidate
  63. GRB050824, HETE-2 Observation
  64. GRB 050826: Swift XRT preliminary analysis results
  65. GRB 050826: BAT refined analysis
  66. GRB050826: Swift/UVOT early upper limits
  67. GRB050824: First 2 hours of power low optical decay?
  68. GRB 050826: Swift XRT position
  69. GRB050826: Swift-BAT detection of a long burst
  70. GRB050824: MASTER final analysis of the OT observations
  71. Possible GRB050825:MASTER optical observations
  72. Swift-BAT trigger 152038 is definitely not a GRB
  73. GRB050824: CORRECTION to UVOT observing times
  74. Swift-BAT trigger 152038 is probably not a GRB
  75. GRB050824: Swift/UVOT detection of fading afterglow
  76. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  77. GRB050824, I-band imaging
  78. GRB050824: Radio Observations
  79. GRB 050824: Spectroscopic redshift from the VLT
  80. GRB 050822: refined XRT analysis
  81. GRB 050824: XRT refined analysis and possible afterglow detection
  82. GRB 050824: BAT refined analysis of a soft weak burst
  83. GRB050824: MASTER:OT decay
  84. GRB050824: MASTER observation OT
  85. GRB050805a: MASTER optical candidat
  86. GRB 050824: ROTSE-III Optical Limits
  87. GRB050824: Swift-BAT detection of a burst
  88. GRB050820A: RTT150 optical observations
  89. GRB050820a: PROMPT RcIc Observations
  90. GRB050815: Maidanak optical observation
  91. XRF050509c: Radio upper limits from GMRT
  92. VLT/UVES spectroscopy of GRB050820
  93. GRB050822: Swift/UVOT upper limits
  94. GRB 050820A BAT observations of second, larger episode of emission
  95. GRB 050822: Swift-BAT refined analysis
  96. GRB050820A: RTT150 optical observations
  97. GRB 050820a - corrections to GCN 3846
  98. Swift/UVOT UV Photometry of GRB 050820B
  99. GRB 050822: ROTSE-III Prompt Optical Limits
  100. GRB 050822: Swift detection of a long burst

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