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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. Gemini Spectroscopy of GRB 050908
  2. GRB 050908: spectroscopic redshift
  3. GRB 050908: Prompt PROMPT Observations
  4. GRB 050908 : Swift XRT position
  5. GRB 050908: KAIT observations
  6. GRB 050908: P60 Confirmation of Optical Afterglow
  7. GRB 050908: Optical Observations
  8. GRB 050908: Swift detection of a burst
  9. Swift trigger 154073 is not a GRB
  10. GRB 050906: Optical observations at the Very Large Telescope
  11. GRB050904: CrAO optical observations
  12. GRB 050904 BAT refined analysis of complete data set
  13. GRB 050904: Subaru Optical Spectroscopy
  14. GRB 050906: MARGE Optical Limits
  15. GRB 050906: Swift-BAT refined analysis
  16. GRB 050906: Swift XRT upper limit
  17. GRB 050906: Radio Observations
  18. GRB 050904: Keck I-band Imaging
  19. GRB050906: P60 Observations
  20. GRB 050904: more VLT NIR observations
  21. GRB 050904: BOOTES early R-band observation
  22. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  23. GRB 050906: Bright galaxy in BAT error box
  24. GRB 050906: Swift/BAT Detection of a possible burst
  25. GRB 050904: More SOAR
  26. GRB 050904: photometric redshift
  27. GRB 050904: Swift/UVOT observations
  28. GRB 050904: Afterglow Astrometry
  29. GRB 050904: NIR object inside the XRT error box
  30. GRB 050904: early Swift XRT analysis results
  31. GRB 050904: SOAR YJ and PROMPT Ic Observations
  32. GRB 050904: BAT refined analysis of partial data set
  33. GRB 050904: TAROT optical measurements
  34. GRB050904: Optical Observations
  35. GRB 050904: Environmental Constraints
  36. GRB 050904: Possible High-Redshift GRB
  37. GRB 050904: SOAR/PROMPT Observations
  38. GRB050904: P60 Observations
  39. GRB 050904: TAROT optical limits
  40. GRB050904: Swift-BAT detection of a probable burst
  41. Swift-BAT triggers 153461-153465 are not GRBs
  42. Retraction of Swift-BAT trigger #153355
  43. GRB 050824: MDM Observations
  44. GRB 050827: Swift XRT preliminary analysis results
  45. IBAS Alerts 2641 and 2642: not a real GRB
  46. Swift Trigger #152652 is not a GRB
  47. GRB 050827 : OSN 1.5m optical observations
  48. GRB 050827: P200 NIR Observations
  49. GRB050827: Swift/UVOT upper limits
  50. GRB 050827: Optical Limit
  51. GRB 050827: XRT possible afterglow detection
  52. GRB 050826 : Lulin R band observation
  53. GRB050824: Maidanak optical limits
  54. GRB050820A: RTT150 optical observations
  55. GRB050827: RTT150 optical observations
  56. GRB 050827: Swift-BAT refined analysis
  57. GRB050827: Swift-BAT detection of a burst
  58. Subaru Observations of GRB050724
  59. GRB 050826: Optical Candidate
  60. GRB050824, HETE-2 Observation
  61. GRB 050826: Swift XRT preliminary analysis results
  62. GRB 050826: BAT refined analysis
  63. GRB050826: Swift/UVOT early upper limits
  64. GRB050824: First 2 hours of power low optical decay?
  65. GRB 050826: Swift XRT position
  66. GRB050826: Swift-BAT detection of a long burst
  67. GRB050824: MASTER final analysis of the OT observations
  68. Possible GRB050825:MASTER optical observations
  69. Swift-BAT trigger 152038 is definitely not a GRB
  70. GRB050824: CORRECTION to UVOT observing times
  71. Swift-BAT trigger 152038 is probably not a GRB
  72. GRB050824: Swift/UVOT detection of fading afterglow
  73. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  74. GRB050824, I-band imaging
  75. GRB050824: Radio Observations
  76. GRB 050824: Spectroscopic redshift from the VLT
  77. GRB 050822: refined XRT analysis
  78. GRB 050824: XRT refined analysis and possible afterglow detection
  79. GRB 050824: BAT refined analysis of a soft weak burst
  80. GRB050824: MASTER:OT decay
  81. GRB050824: MASTER observation OT
  82. GRB050805a: MASTER optical candidat
  83. GRB 050824: ROTSE-III Optical Limits
  84. GRB050824: Swift-BAT detection of a burst
  85. GRB 050824 optical candidate
  86. GRB050820A: RTT150 optical observations
  87. GRB050820a: PROMPT RcIc Observations
  88. GRB050815: Maidanak optical observation
  89. XRF050509c: Radio upper limits from GMRT
  90. VLT/UVES spectroscopy of GRB050820
  91. GRB050822: Swift/UVOT upper limits
  92. GRB 050820A BAT observations of second, larger episode of emission
  93. GRB050813: Maidanak I-band observations
  94. GRB 050822: Swift-BAT refined analysis
  95. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  96. GRB050820B at FRAM
  97. GRB050820A: RTT150 optical observations
  98. GRB 050820a - corrections to GCN 3846
  99. Swift/UVOT UV Photometry of GRB 050820B
  100. GRB 050822: ROTSE-III Prompt Optical Limits

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