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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. GRB 081024A: ROTSE-III Optical Limits
  2. GRB 081024: Swift detection of a burst
  3. GRB 081022, Swift-BAT refined analysis
  4. GRB 081016A: Swift-XRT refined analysis
  5. GRB 081022: Swift detection of a burst
  6. GRB 081012: Swift-XRT Refined Analysis
  7. Swift trigger 332287 is not a GRB
  8. Swift detection of a possible burst (trigger 332287)
  9. GRB 081012 - Enhanced Swift XRT position
  10. GRB 081017, Swift-BAT refined analysis
  11. GRB 081017: REM early observations
  12. GRB 081017: Swift detection of a burst
  13. GRB 081016B, Swift-BAT refined analysis
  14. GRB 081016B: Swift/UVOT Upper Limits
  15. GRB 081011: Swift XRT refined analysis
  16. GRB 081016B: Swift-XRT Team refined Analysis
  17. GRB 081016B: Enhanced Swift-XRT position
  18. GRB 081016B: ROTSE-III Optical Limits
  19. GRB 081016B: Swift detection of a burst
  20. GRB 081011: Enhanced Swift-XRT position
  21. GRB 081016: Swift-XRT candidate afterglow detection
  22. Swift detection of flare on CC Eri
  23. GRB 081016: A long GRB discovered by INTEGRAL
  24. Trigger 331721 Due to Swift startracker loss-of-lock
  25. Detection of flare star Algol in Swift-BAT slew data
  26. GRB 081009: Fermi GBM detection
  27. GRB 081012: GROND upper limits
  28. GRB 081008: Galaxy associated with z=1.967 absorber
  29. Swift-BAT triggered on the flare star Algol
  30. GRB 081012: Fermi GBM detection
  31. GRB 081007 and GRB 081007B: Fermi GBM detection
  32. GRB 080430: optical observations
  33. GRB 081008 optical upper limit
  34. GRB 081012: Observations from NOT
  35. GRB 081012: Swift/UVOT analysis of initial observations
  36. GRB 081012: Swift/XRT detection
  37. GRB 081012, Swift-BAT refined analysis
  38. GRB 081012: ROTSE-III Optical Limits
  39. GRB 081012: Swift detection of a burst
  40. Revised table for GRB 081011 UVOT detections
  41. GRB081011: UVOT detection of an optical afterglow
  42. GRB 081011: Swift/XRT detection
  43. GRB 081011, Swift-BAT refined analysis
  44. GRB 081008, SMARTS optical/IR afterglow observations
  45. GRB 081011: Swift detection of a burst
  46. GRB 081007: Radio Detection
  47. Konus-Wind observation of GRB 081001
  48. GRB 081007: Rapid PROMPT Detections
  49. GRB 081008, Swift-BAT refined analysis
  50. GRB 081008: VLT redshift confirmation
  51. GRB 081008: Swift-XRT Refined Analysis
  52. GRB081008: Swift/UVOT observations
  53. GRB 081008: Enhanced Swift-XRT position
  54. GRB 081008: Gemini-South Absorption Redshiftt
  55. GRB 081008: VLT/FORS2 spectroscopy
  56. GRB 081008: Swift detection of a burst with optical afterglow
  57. GRB 081008: ROTSE-III Detection of Optical Counterpart
  58. GRB081006B: Fermi GBM detection
  59. GRB081006: Fermi GBM detection
  60. GRB081007: Swift/UVOT Observations
  61. GRB 081007, SMARTS optical afterglow observations
  62. GRB 081007, Swift-BAT refined analysis
  63. GRB 081007: Early RAPTOR measurements of optical counterpart
  64. GRB 081007: Swift-XRT Team refined analysis
  65. GRB 081007: Gemini-south redshift
  66. GRB 081007: Enhanced Swift-XRT position
  67. GRB 081007, Faulkes Telescope North optical observations
  68. GRB 081007, SMARTS optical/IR afterglow observations
  69. GRB 081007: REM NIR and optical counterpart
  70. GRB 081007: Swift detection of a burst with optical afterglow
  71. GRB081003C: GLAST Burst Monitor detection
  72. Fermi GBM detection of additional bursts from AXP 1E1547.0-5408
  73. INTEGRAL ToO observation of the AXP 1E 1547.0-5408
  74. GRB 081003B: TAROT Calern observatory optical observations
  75. AXP 1E 1547.0-5408: Swift/UVOT Upper Limits
  76. GRB 081003B: Swift-XRT upper limit
  77. GRB 081003A: OSN optical observations
  78. GRB 081001: Further observations from OSN
  79. AXP 1E1547.0-5408: Swift-XRT Team refined analysis
  80. GRB081003B: Optical limits from Spain
  81. GRB 081003A: Swift-XRT Team position and analysis
  82. Swift-BAT refined analysis of AXP 1E1547.0-5408 (Trigger 330353)
  83. GRB 081003B: a long GRB detected with INTEGRAL
  84. GRB 080928: Fermi GBM detection
  85. AXP 1E1547.0-5408 (SGR 1550-5418): Fermi GBM detection
  86. GRB 081003: A long GRB discovered by INTEGRAL
  87. SGR 1550-5418 = AXP 1E1547.0-5408 (Trigger 330353)
  88. Swift discovery of a new Soft Gamma Repeater SGR 1550-5418
  89. Trigger 330353: Swift detection of a Galactic short soft burst
  90. GRB 081001: Observations from OSN
  91. GRB 080925: Suzaku WAM observation of the prompt emission
  92. GRB 081001: Swift UVOT Observations
  93. GRB 081001: Swift-XRT position
  94. GRB081001: optical limit from ASH-Centurion
  95. GRB081001: SuperAGILE Localization of a long GRB
  96. GRB080928: redshift retraction
  97. GRB 080928: Watcher observations
  98. GRB 080927: Fermi GBM detection
  99. GRB 080928: VLT redshift
  100. GRB080928: Gemini-South Absorption Redshift

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