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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"

28046 results found.

  1. GRB 050925: Second Epoch WSRT Radio Observations
  2. GRB 051001: I-band limit
  3. GRB 051001: AAT infra-red observations
  4. GRB 051001: Swift-BAT refined analysis
  5. GRB 051001: Swift Detection of a Burst
  6. GRB 050820A: NIR photometry at the TNG
  7. GRB050925: Swift/XRT limits
  8. GRB/SGR 050925: IR Observations
  9. GRB 050922C: break in the lightcurve
  10. GRB050925: Swift UVOT upper limits
  11. Refined analysis of the Swift-BAT soft short burst
  12. GRB050925: Faulkes Telescope North R-band limit
  13. GRB050925: Swift-BAT detection of a short burst
  14. GRB050922C: TNG spectroscopic observations
  15. GRB050922B: refined XRT analysis
  16. GRB050922B: Swift UVOT early upper limits.
  17. GRB050922C: Optical Observations
  18. GRB 050922C: Swift XRT refined analysis
  19. HETE Fregate observations of GRB 050922C
  20. GRB 050922C: Swift-BAT refined analysis
  21. GRB 050922B: Swift-BAT refined analysis
  22. GRB 050922C: optical obserations
  23. GRB 050922C: NOT optical observations
  24. GRB 050922C: Swift detection of a bright burst
  25. GRB 050922B: ROTSE-III Optical Limits
  26. GRB 050922B,optical observation
  27. GRB050922B: Swift-BAT detection of a weak long burst
  28. GRB050820B: analysis of the XMM-Newton observation
  29. GRB050916: Swift/UVOT Upper Limits
  30. GRB 050916: Swift-BAT refined analysis
  31. Swift-BAT trigger 155764 is not a GRB
  32. Swift-BAT trigger 155764 is probably not a GRB
  33. Swift trigger 155764: bad XRT centroid
  34. Swift-BAT trigger 155535 is definitely not a GRB
  35. GRB050916 : Swift-XRT refined analysis
  36. GRB 050915B: Swift-BAT refined analysis
  37. GRB 050915B: Swift/UVOT Upper Limits
  38. GRB 050915a: IR Transient
  39. GRB 050915b, SMARTS optical/IR observations
  40. GRB050915B: Swift-BAT detection of a long bright burst
  41. GRB050915: Swift/UVOT upper limits
  42. GRB 050915: IR Observations
  43. GRB 050915: Swift XRT refined analysis
  44. GRB 050915: Swift-BAT refined analysis
  45. GRB 050915: Swift detection of a GRB
  46. GRB050911: Upper limit on X-ray afterglow
  47. Swift-BAT trigger 155072 ground analysis
  48. Swift-BAT trigger 155072 is probably not a GRB
  49. GRB 050908: DEIMOS spectrum and further analysis
  50. GRB 050911, optical content of Swift/XRT error box
  51. GRB 050911: Swift-BAT refined analysis
  52. GRB 050911: z~0.16 cluster in the field
  53. GRB050911: Swift-BAT detection of a long burst
  54. GRB 050910a: TAROT early optical limits
  55. WIRO observations in I of GRB 050908
  56. GRB 050906: Possible X-ray Counterpart
  57. GRB050908: Swift/UVOT Early upper limits
  58. GRB050908 : Swift-XRT refined analysis
  59. GRB 050908: Swift-BAT refined analysis
  60. GRB 050908: Optical observations
  61. GRB 050908: Optical Observations
  62. GRB 050908: Swift detection of a burst
  63. GRB 050906: Optical observations at the Very Large Telescope
  64. GRB 050904 BAT refined analysis of complete data set
  65. GRB 050904: Subaru Optical Spectroscopy
  66. GRB 050906: MARGE Optical Limits
  67. GRB 050906: Swift-BAT refined analysis
  68. GRB 050906: Swift XRT upper limit
  69. GRB 050906: Radio Observations
  70. GRB 050904: Keck I-band Imaging
  71. GRB050906: P60 Observations
  72. GRB 050904: more VLT NIR observations
  73. GRB 050904: photometric redshift
  74. GRB 050904: Swift/UVOT observations
  75. GRB 050904: NIR object inside the XRT error box
  76. GRB 050904: early Swift XRT analysis results
  77. GRB 050904: SOAR YJ and PROMPT Ic Observations
  78. GRB050904: Optical Observations
  79. GRB050904: P60 Observations
  80. GRB 050904: TAROT optical limits
  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. GRB 050826 : Lulin R band observation
  87. GRB050824: Maidanak optical limits
  88. GRB 050827: Swift-BAT refined analysis
  89. Subaru Observations of GRB050724
  90. GRB 050826: Optical Candidate
  91. GRB 050826: Swift XRT preliminary analysis results
  92. GRB 050826: BAT refined analysis
  93. GRB050826: Swift/UVOT early upper limits
  94. GRB050826: Swift-BAT detection of a long burst
  95. GRB050824: MASTER final analysis of the OT observations
  96. Swift-BAT trigger 152038 is probably not a GRB
  97. GRB 050824: XRT refined analysis and possible afterglow detection
  98. GRB 050824: BAT refined analysis of a soft weak burst
  99. GRB050824: MASTER:OT decay
  100. GRB050824: MASTER observation OT

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