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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. IBAS Alert 2675 : not a GRB
  2. GRB051008: optical candidate
  3. GRB 051008: - a high redshift high-luminosity burst?
  4. GRB 051008 - a low redshift low-luminosity burst?
  5. IBAS Alert 2673: not a real GRB
  6. GRB051011: bright nebulae near error box
  7. GRB051011: MASTER optical observation
  8. GRB051008: optical observation
  9. GRB051008: Swift XRT refined analysis
  10. GRB051008 - Swift UVOT upper limits
  11. Konus-Wind observation of GRB 051008
  12. GRB051008: Final refined analysis of the Swift-BAT burst
  13. GRB 051008: R-band upper limit
  14. GRB051008: Refined analysis of the Swift-BAT burst
  15. GRB051008: Radio Observation
  16. GRB 051008: Swift XRT position
  17. GRB 051008, optical observations
  18. GRB 051008: early Swift XRT analysis
  19. GRB 051008: Swift UVOT Candidate
  20. GRB051008: Swift-BAT detection of a bright burst
  21. GRB 051006: P60 Observations
  22. grb test
  23. GRB 051006: XRT refined analysis
  24. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  25. GRB 051006: optical observations at Sierra Nevada
  26. GRB051006: Refined analysis of the Swift-BAT burst
  27. GRB 051006: XRT position
  28. GRB051006: Swift detection of a burst
  29. GRB 050906, summary of radio observations
  30. Swift-BAT triggers 158261 and 158262 Retraction
  31. GRB051001: Swift UVOT Upper Limits
  32. GRB 050925: Second Epoch WSRT Radio Observations
  33. GRB 051001: Swift XRT refined analysis
  34. GRB 051001, optical observations at Mt. John
  35. GRB 051001: I-band limit
  36. GRB 051001: AAT infra-red observations
  37. GRB 051001: Swift-BAT refined analysis
  38. GRB 051001: Swift Detection of a Burst
  39. GRB 051001: ROTSE-III Optical Limits
  40. GRB050908: optical observations
  41. GRB050922C: optical observation
  42. GRB050922B: optical limit
  43. GRB 050922C: further VLT observations
  44. GRB 050820A: NIR photometry at the TNG
  45. GRB050922C: UVES/VLT high resolution spectroscopy
  46. GRB050925: Swift/XRT limits
  47. GRB/SGR 050925: IR Observations
  48. GRB050922C - Swift UVOT preliminary analysis
  49. GRB 050922C: break in the lightcurve
  50. GRB 050925: WSRT Radio Observations
  51. GRB050925: Swift UVOT upper limits
  52. Refined analysis of the Swift-BAT soft short burst
  53. GRB 050925 : I-band observation at Xinglong observatory
  54. GRB050925: Faulkes Telescope North R-band limit
  55. GRB050925: Swift-BAT detection of a short burst
  56. GRB 050922B: Correction to BAT refined analysis, longer burst
  57. GRB050922C: TNG spectroscopic observations
  58. GRB050922B: refined XRT analysis
  59. Konus-Wind observation of GRB 050922C
  60. GRB 050922C: Refined redshift
  61. GRB050922B: Swift UVOT early upper limits.
  62. GRB OT observation
  63. GRB050922C: observation at MonteBoo
  64. INT 2.5m limit for GRB050922B
  65. GRB 050922B: optical limit
  66. GRB050922C: Optical Observations
  67. GRB 050922C: Swift XRT refined analysis
  68. HETE Fregate observations of GRB 050922C
  69. GRB 050922C: Swift-BAT refined analysis
  70. GRB 050922B: Swift-BAT refined analysis
  71. GRB050922C: optical observations
  72. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  73. GRB 050922C: optical obserations
  74. GRB 050922C: NOT optical observations
  75. GRB 050922A: Analysis of Swift/XRT TOO observation
  76. GRB 050922C: Swift detection of a bright burst
  77. GRB 050922C: ROTSE-IIId Refined Analysis
  78. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  79. GRB 050922B: ROTSE-III Optical Limits
  80. GRB 050922B,optical observation
  81. GRB050922B: Swift-BAT detection of a weak long burst
  82. Possible GRB 050922 detected by INTEGRAL
  83. GRB050918: Possible Swift/XRT detected afterglow
  84. GRB050820B: analysis of the XMM-Newton observation
  85. GRB050916: Swift/UVOT Upper Limits
  86. GRB 050916: Swift-BAT refined analysis
  87. GRB 050918 - A long GRB detected by INTEGRAL
  88. GRB 050915a: Radio Observations
  89. Swift-BAT trigger 155764 is not a GRB
  90. Swift-BAT trigger 155764 is probably not a GRB
  91. Swift trigger 155764: bad XRT centroid
  92. Swift-BAT trigger 155535 is definitely not a GRB
  93. GRB050916 : Swift-XRT refined analysis
  94. GRB 050916: XRT position
  95. GRB 050915b, SMARTS optical/IR observations of the XRT position
  96. GRB 050915B: Swift-BAT refined analysis
  97. GRB 050915B: Swift/UVOT Upper Limits
  98. GRB050916: Swift-BAT detection of a long weak burst
  99. GRB 050915a: IR Transient
  100. GRB 050915B: XRT position

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