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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 051105B (INTEGRAL 2701): Optical observation
  2. GRB 051105: Swift-BAT refined analysis
  3. GRB 051105: Optical limit
  4. GRB 051105: Swift detection of a short burst
  5. IBAS Alert 2700: Not a GRB
  6. GRB 051016B host spectroscopy and redshift
  7. GRB051016B: optical observation
  8. Recent GRB UBVRcIc field photometry
  9. Konus-Wind observation of GRB 051028
  10. GRB051028:MASTER correction and final results
  11. GRB 051022: RTT150 optical observations
  12. GRB 051021A: RTT150 optical observations
  13. GRB051028 SARA Observation
  14. GRB051028: optical observations
  15. GRB051028: Swift/UVOT upper limits
  16. GRB051028: confirmation of the afterglow
  17. GRB051028: WHT optical candidate
  18. GRB051028: Swift XRT Position
  19. GRB051028:MASTER observations
  20. GRB 051028 (=H3951): A GRB localized by HETE
  21. GRB051028:MASTER optical observations
  22. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  23. GRB051022: Swift XRT measurement of jet break
  24. SGR 1806-20: continued moderate activity seen with INTEGRAL
  25. GRB051021B: Swift/UVOT Upper limits
  26. GRB 051021, Optical Observations
  27. GRB 051022: XRT Refined Spectral and Temporal Analysis
  28. GRB 051022, refined optical astrometry
  29. Chandra Observations of GRB 051022
  30. GRB051012: Swift-XRT analysis
  31. GRB 051022 Chandra Observations scheduled
  32. GRB051021B: Swift XRT refined analysis
  33. GRB051021a: optical observations
  34. GRB 051022: WSRT Radio Detection
  35. GRB 051022, mm counterpart
  36. GRB051022: host galaxy redshift
  37. GRB 051022: Swift/UVOT Upper Limits
  38. GRB051022: Radio Counterpart
  39. GRB051022: IR observations
  40. GRB 051022: SOAR JKs Observations
  41. GRB051021A: Swift XRT refined analysis
  42. Konus-Wind observation of GRB 051022
  43. GRB051022: Optical Observations
  44. GRB 051022: Magellan NIR imaging
  45. GRB 051021: PROMPT RcIc Observations
  46. GRB051021b: Magellan IR Imaging
  47. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  48. GRB 051021: Correction
  49. GRB 051022, J & K-band observation
  50. GRB 051021, SMARTS optical/IR observations
  51. GRB051022: Swift XRT Position
  52. GRB 051021: P200 Ks Observations
  53. IPN triangulation of GRB051022 (=H3950)
  54. GRB 051021: MDM Upper Limit
  55. GRB 051022 (=H3950): SXC Flight Localization is Valid
  56. GRB051021: Swift/UVOT Upper Limits
  57. GRB 051021B: Refined analysis of the Swift-BAT burst
  58. GRB 051022: SSO40 Optical Observations
  59. GRB051022,optical observation
  60. GRB 051022A: ROTSE-III Optical Limits
  61. GRB051022 (=H3590), A GRB Detected By HETE
  62. GRB 051022: Optical observations
  63. GRB 051021,optical observation
  64. GRB051021B: Swift XRT Position
  65. GRB 051021: SOAR NIR Observations
  66. GRB 051021B: Swift detection of a burst
  67. GRB051021: Swift XRT analysis
  68. GRB051021 (=H3947): Refined Analysis
  69. GRB 051021 : optical afterglow observation at Lulin
  70. GRB 051021: Optical observations
  71. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  72. GRB 051021: Optical observations and candidate afterglow
  73. GRB051021.63
  74. GRB051021.6: MASTER optical observation
  75. Swift-BAT trigger 160640 is not a real GRB
  76. GRB051021: A GRB Localized by HETE
  77. Swift-BAT trigger 160619 is not a GRB
  78. Swift-BAT triggered on a posible CR Shower or possible GRB
  79. GRB 050502b: Optical limit
  80. GRB 051016b: Optical limit
  81. Afterglow candidate of GRB 051016B observed at Lulin
  82. GRB 051016b: Gemini Near IR Observations
  83. GRB 051016A: Swift/UVOT upper limits
  84. GRB 051016B: refined analysis of the Swift/XRT data
  85. GRB 051016B: Swift/UVOT detection
  86. GRB 051016B,optical observation
  87. GRB 051016B : Optical follow-up at Lulin
  88. GRB 051016B: Refined analysis of the Swift-BAT burst
  89. GRB 051016B: Swift detection of a soft burst
  90. GRB 051016: Swift-BAT refined analysis
  91. GRB051016 XMM-Newton observation
  92. GRB051016: Swift XRT refined analysis.
  93. GRB051016: Planned XMM-Newton observation
  94. GRB 051016: LCO optical and near-IR imaging
  95. GRB 051016: PROMPT Observations
  96. GRB051016: Swift detection of a burst
  97. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  98. GRB051006: optical observations
  99. GRB 051012: Swift-BAT detection of burst yesterday
  100. Swift trigger 159578 is not a burst

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