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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 051105A, 2nd epoch optical observations
  2. GRB 051105a: MDM Observations
  3. GRB 051105A: TNG optical observations
  4. GRB051105A: Swift/UVOT Observations
  5. GRB 051105A, radio observations
  6. GRB051103:_MASTER_optical_observations
  7. IPN triangulation and Konus spectrum of the bright short/hard GRB051103
  8. GRB 051105A, optical observations
  9. XRT observations of GRB 051105A
  10. GRB 051105: Swift-BAT improved refined analysis
  11. GRB 051105b: ART optical limits
  12. GRB051105B - A long GRB detected by INTEGRAL
  13. GRB 051105B (INTEGRAL 2701): Optical observation
  14. GRB 051105: Swift-BAT refined analysis
  15. GRB 051105: Optical limit
  16. GRB 051105: Swift detection of a short burst
  17. IBAS Alert 2700: Not a GRB
  18. GRB 051016B host spectroscopy and redshift
  19. GRB051016B: optical observation
  20. Recent GRB UBVRcIc field photometry
  21. Konus-Wind observation of GRB 051028
  22. GRB051028:MASTER correction and final results
  23. GRB 051022: RTT150 optical observations
  24. GRB 051021A: RTT150 optical observations
  25. GRB051028 SARA Observation
  26. GRB051028: optical observations
  27. GRB051028: Swift/UVOT upper limits
  28. GRB051028: confirmation of the afterglow
  29. GRB051028: WHT optical candidate
  30. GRB051028: Swift XRT Position
  31. GRB051028:MASTER observations
  32. GRB 051028 (=H3951): A GRB localized by HETE
  33. GRB051028:MASTER optical observations
  34. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  35. GRB051022: Swift XRT measurement of jet break
  36. SGR 1806-20: continued moderate activity seen with INTEGRAL
  37. GRB051021B: Swift/UVOT Upper limits
  38. GRB 051021, Optical Observations
  39. GRB 051022: XRT Refined Spectral and Temporal Analysis
  40. GRB 051022, refined optical astrometry
  41. Chandra Observations of GRB 051022
  42. GRB051012: Swift-XRT analysis
  43. GRB 051022 Chandra Observations scheduled
  44. GRB051021B: Swift XRT refined analysis
  45. GRB051021a: optical observations
  46. GRB 051022: WSRT Radio Detection
  47. GRB 051022, mm counterpart
  48. GRB051022: host galaxy redshift
  49. GRB 051022: Swift/UVOT Upper Limits
  50. GRB051022: Radio Counterpart
  51. GRB051022: IR observations
  52. GRB 051022: SOAR JKs Observations
  53. GRB051021A: Swift XRT refined analysis
  54. Konus-Wind observation of GRB 051022
  55. GRB051022: Optical Observations
  56. GRB 051022: Magellan NIR imaging
  57. GRB 051021: PROMPT RcIc Observations
  58. GRB051021b: Magellan IR Imaging
  59. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  60. GRB 051021: Correction
  61. GRB 051022, J & K-band observation
  62. GRB 051021, SMARTS optical/IR observations
  63. GRB051022: Swift XRT Position
  64. GRB 051021: P200 Ks Observations
  65. IPN triangulation of GRB051022 (=H3950)
  66. GRB 051021: MDM Upper Limit
  67. GRB 051022 (=H3950): SXC Flight Localization is Valid
  68. GRB051021: Swift/UVOT Upper Limits
  69. GRB 051021B: Refined analysis of the Swift-BAT burst
  70. GRB 051022: SSO40 Optical Observations
  71. GRB051022,optical observation
  72. GRB 051022A: ROTSE-III Optical Limits
  73. GRB051022 (=H3590), A GRB Detected By HETE
  74. GRB 051022: Optical observations
  75. GRB 051021,optical observation
  76. GRB051021B: Swift XRT Position
  77. GRB 051021: SOAR NIR Observations
  78. GRB 051021B: Swift detection of a burst
  79. GRB051021: Swift XRT analysis
  80. GRB051021 (=H3947): Refined Analysis
  81. GRB 051021 : optical afterglow observation at Lulin
  82. GRB 051021: Optical observations
  83. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  84. GRB 051021: Optical observations and candidate afterglow
  85. GRB051021.63
  86. GRB051021.6: MASTER optical observation
  87. Swift-BAT trigger 160640 is not a real GRB
  88. GRB051021: A GRB Localized by HETE
  89. Swift-BAT trigger 160619 is not a GRB
  90. Swift-BAT triggered on a posible CR Shower or possible GRB
  91. GRB 050502b: Optical limit
  92. GRB 051016b: Optical limit
  93. Afterglow candidate of GRB 051016B observed at Lulin
  94. GRB 051016b: Gemini Near IR Observations
  95. GRB 051016A: Swift/UVOT upper limits
  96. GRB 051016B: refined analysis of the Swift/XRT data
  97. GRB 051016B: Swift/UVOT detection
  98. GRB 051016B,optical observation
  99. GRB 051016B : Optical follow-up at Lulin
  100. GRB 051016B: Refined analysis of the Swift-BAT burst

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