Skip to main content
Circulars over Kafka event name backfill. See news and announcements

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. GRB 050922B,optical observation
  2. GRB050922B: Swift-BAT detection of a weak long burst
  3. Possible GRB 050922 detected by INTEGRAL
  4. GRB050918: Possible Swift/XRT detected afterglow
  5. GRB050820B: analysis of the XMM-Newton observation
  6. GRB050916: Swift/UVOT Upper Limits
  7. GRB 050916: Swift-BAT refined analysis
  8. GRB 050918 - A long GRB detected by INTEGRAL
  9. GRB 050915a: Radio Observations
  10. Swift-BAT trigger 155764 is not a GRB
  11. Swift-BAT trigger 155764 is probably not a GRB
  12. Swift trigger 155764: bad XRT centroid
  13. Swift-BAT trigger 155535 is definitely not a GRB
  14. GRB050916 : Swift-XRT refined analysis
  15. GRB 050916: XRT position
  16. GRB 050915b, SMARTS optical/IR observations of the XRT position
  17. GRB 050915B: Swift-BAT refined analysis
  18. GRB 050915B: Swift/UVOT Upper Limits
  19. GRB050916: Swift-BAT detection of a long weak burst
  20. GRB 050915a: IR Transient
  21. GRB 050915B: XRT position
  22. GRB 050915b, SMARTS optical/IR observations
  23. GRB050915B: Swift-BAT detection of a long bright burst
  24. GRB050915: Swift/UVOT upper limits
  25. GRB 050915: KAIT optical limit
  26. GRB 050915: IR Observations
  27. GRB 050915: Swift XRT refined analysis
  28. GRB 050915: Swift-BAT refined analysis
  29. GRB050915: P60 Optical Observations
  30. GRB050915, optical observations
  31. GRB050915: XRT position
  32. GRB 050915: ROTSE-III optical limits
  33. GRB 050915: Swift detection of a GRB
  34. GRB050911: Upper limit on X-ray afterglow
  35. Swift-BAT trigger 155072 ground analysis
  36. Swift-BAT trigger 155072 is probably not a GRB
  37. GRB050914: XRT position probably due to cosmic ray
  38. GRB 050911: LCO limits on a variable source
  39. GRB 050908: DEIMOS spectrum and further analysis
  40. Swift is in normal operation
  41. GRB050911: Swift UVOT followup observations
  42. GRB 050911, optical content of Swift/XRT error box
  43. GRB050911: Swift-XRT position
  44. GRB 050911: LCO observations
  45. GRB 050911, optical observations
  46. GRB 050911: Swift-BAT refined analysis
  47. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  48. GRB 050911: z~0.16 cluster in the field
  49. GRB050911: Swift-BAT detection of a long burst
  50. GRB050908: detection of Swift/UVOT optical counterpart
  51. GRB 050910a: TAROT early optical limits
  52. RBO GRB 050908 observations
  53. WIRO observations in I of GRB 050908
  54. GRB 050906: Possible X-ray Counterpart
  55. GRB 050906: RTT150 optical observations
  56. GRB050908: Swift/UVOT Early upper limits
  57. GRB050908: VLT R-band decay index.
  58. GRB050908 : Swift-XRT refined analysis
  59. GRB 050908: Swift-BAT refined analysis
  60. GRB 050908: Optical observations
  61. Gemini Spectroscopy of GRB 050908
  62. GRB 050908: spectroscopic redshift
  63. GRB 050908: Prompt PROMPT Observations
  64. GRB 050908 : Swift XRT position
  65. GRB 050908: KAIT observations
  66. GRB 050908: P60 Confirmation of Optical Afterglow
  67. GRB 050908: Optical Observations
  68. GRB 050908: Swift detection of a burst
  69. Swift trigger 154073 is not a GRB
  70. GRB 050906: Optical observations at the Very Large Telescope
  71. GRB050904: CrAO optical observations
  72. GRB 050904 BAT refined analysis of complete data set
  73. GRB 050904: Subaru Optical Spectroscopy
  74. GRB 050906: MARGE Optical Limits
  75. GRB 050906: Swift-BAT refined analysis
  76. GRB 050906: Swift XRT upper limit
  77. GRB 050906: Radio Observations
  78. GRB 050904: Keck I-band Imaging
  79. GRB050906: P60 Observations
  80. GRB 050904: more VLT NIR observations
  81. GRB 050904: BOOTES early R-band observation
  82. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  83. GRB 050906: Bright galaxy in BAT error box
  84. GRB 050906: Swift/BAT Detection of a possible burst
  85. GRB 050904: More SOAR
  86. GRB 050904: photometric redshift
  87. GRB 050904: Swift/UVOT observations
  88. GRB 050904: Afterglow Astrometry
  89. GRB 050904: NIR object inside the XRT error box
  90. GRB 050904: early Swift XRT analysis results
  91. GRB 050904: SOAR YJ and PROMPT Ic Observations
  92. GRB 050904: BAT refined analysis of partial data set
  93. GRB 050904: TAROT optical measurements
  94. GRB050904: Optical Observations
  95. GRB 050904: Environmental Constraints
  96. GRB 050904: Possible High-Redshift GRB
  97. GRB 050904: SOAR/PROMPT Observations
  98. GRB050904: P60 Observations
  99. GRB 050904: TAROT optical limits
  100. GRB050904: Swift-BAT detection of a probable burst

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov