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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. WIRO observations in I of GRB 050908
  2. GRB 050906: Possible X-ray Counterpart
  3. GRB 050906: RTT150 optical observations
  4. GRB050908: Swift/UVOT Early upper limits
  5. GRB050908: VLT R-band decay index.
  6. GRB050908 : Swift-XRT refined analysis
  7. GRB 050908: Swift-BAT refined analysis
  8. GRB 050908: Optical observations
  9. Gemini Spectroscopy of GRB 050908
  10. GRB 050908: spectroscopic redshift
  11. GRB 050908: Prompt PROMPT Observations
  12. GRB 050908 : Swift XRT position
  13. GRB 050908: KAIT observations
  14. GRB 050908: P60 Confirmation of Optical Afterglow
  15. GRB 050908: Optical Observations
  16. GRB 050908: Swift detection of a burst
  17. Swift trigger 154073 is not a GRB
  18. GRB 050906: Optical observations at the Very Large Telescope
  19. GRB050904: CrAO optical observations
  20. GRB 050904 BAT refined analysis of complete data set
  21. GRB 050904: Subaru Optical Spectroscopy
  22. GRB 050906: MARGE Optical Limits
  23. GRB 050906: Swift-BAT refined analysis
  24. GRB 050906: Swift XRT upper limit
  25. GRB 050906: Radio Observations
  26. GRB 050904: Keck I-band Imaging
  27. GRB050906: P60 Observations
  28. GRB 050904: more VLT NIR observations
  29. GRB 050904: BOOTES early R-band observation
  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. GRB 050904: TAROT optical measurements
  42. GRB050904: Optical Observations
  43. GRB 050904: Environmental Constraints
  44. GRB 050904: Possible High-Redshift GRB
  45. GRB 050904: SOAR/PROMPT Observations
  46. GRB050904: P60 Observations
  47. GRB 050904: TAROT optical limits
  48. GRB050904: Swift-BAT detection of a probable burst
  49. Swift-BAT triggers 153461-153465 are not GRBs
  50. Retraction of Swift-BAT trigger #153355
  51. GRB 050824: MDM Observations
  52. GRB 050827: Swift XRT preliminary analysis results
  53. IBAS Alerts 2641 and 2642: not a real GRB
  54. Swift Trigger #152652 is not a GRB
  55. GRB 050827 : OSN 1.5m optical observations
  56. GRB 050827: P200 NIR Observations
  57. GRB050827: Swift/UVOT upper limits
  58. GRB 050827: Optical Limit
  59. GRB 050827: XRT possible afterglow detection
  60. GRB 050826 : Lulin R band observation
  61. GRB050824: Maidanak optical limits
  62. GRB050820A: RTT150 optical observations
  63. GRB050827: RTT150 optical observations
  64. GRB 050827: Swift-BAT refined analysis
  65. GRB050827: Swift-BAT detection of a burst
  66. Subaru Observations of GRB050724
  67. GRB 050826: Optical Candidate
  68. GRB050824, HETE-2 Observation
  69. GRB 050826: Swift XRT preliminary analysis results
  70. GRB 050826: BAT refined analysis
  71. GRB050826: Swift/UVOT early upper limits
  72. GRB050824: First 2 hours of power low optical decay?
  73. GRB 050826: Swift XRT position
  74. GRB050826: Swift-BAT detection of a long burst
  75. GRB050824: MASTER final analysis of the OT observations
  76. Possible GRB050825:MASTER optical observations
  77. Swift-BAT trigger 152038 is definitely not a GRB
  78. GRB050824: CORRECTION to UVOT observing times
  79. Swift-BAT trigger 152038 is probably not a GRB
  80. GRB050824: Swift/UVOT detection of fading afterglow
  81. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  82. GRB050824, I-band imaging
  83. GRB050824: Radio Observations
  84. GRB 050824: Spectroscopic redshift from the VLT
  85. GRB 050822: refined XRT analysis
  86. GRB 050824: XRT refined analysis and possible afterglow detection
  87. GRB 050824: BAT refined analysis of a soft weak burst
  88. GRB050824: MASTER:OT decay
  89. GRB050824: MASTER observation OT
  90. GRB050805a: MASTER optical candidat
  91. GRB 050824: ROTSE-III Optical Limits
  92. GRB050824: Swift-BAT detection of a burst
  93. GRB 050824 optical candidate
  94. GRB050820A: RTT150 optical observations
  95. GRB050820a: PROMPT RcIc Observations
  96. GRB050815: Maidanak optical observation
  97. XRF050509c: Radio upper limits from GMRT
  98. VLT/UVES spectroscopy of GRB050820
  99. GRB050822: Swift/UVOT upper limits
  100. GRB 050820A BAT observations of second, larger episode of emission

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