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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 051103, optical observations
  2. GRB051103: MASTER: OT limit and host galaxy candidates
  3. GRB051028: Swift-XRT refined analysis
  4. GRB 051105a, observation from Naini Tal and OSN
  5. GRB 051105A, 2nd epoch optical observations
  6. GRB 051105a: MDM Observations
  7. GRB 051105A: TNG optical observations
  8. GRB051105A: Swift/UVOT Observations
  9. GRB 051105A, radio observations
  10. GRB051103:_MASTER_optical_observations
  11. IPN triangulation and Konus spectrum of the bright short/hard GRB051103
  12. GRB 051105A, optical observations
  13. XRT observations of GRB 051105A
  14. GRB 051105: Swift-BAT improved refined analysis
  15. GRB 051105b: ART optical limits
  16. GRB051105B - A long GRB detected by INTEGRAL
  17. GRB 051105B (INTEGRAL 2701): Optical observation
  18. GRB 051105: Swift-BAT refined analysis
  19. GRB 051105: Optical limit
  20. GRB 051105: Swift detection of a short burst
  21. IBAS Alert 2700: Not a GRB
  22. GRB 051016B host spectroscopy and redshift
  23. GRB051016B: optical observation
  24. Recent GRB UBVRcIc field photometry
  25. Konus-Wind observation of GRB 051028
  26. GRB051028:MASTER correction and final results
  27. GRB 051022: RTT150 optical observations
  28. GRB 051021A: RTT150 optical observations
  29. GRB051028 SARA Observation
  30. GRB051028: optical observations
  31. GRB051028: Swift/UVOT upper limits
  32. GRB051028: confirmation of the afterglow
  33. GRB051028: WHT optical candidate
  34. GRB051028: Swift XRT Position
  35. GRB051028:MASTER observations
  36. GRB 051028 (=H3951): A GRB localized by HETE
  37. GRB051028:MASTER optical observations
  38. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  39. GRB051022: Swift XRT measurement of jet break
  40. SGR 1806-20: continued moderate activity seen with INTEGRAL
  41. GRB051021B: Swift/UVOT Upper limits
  42. GRB 051021, Optical Observations
  43. GRB 051022: XRT Refined Spectral and Temporal Analysis
  44. GRB 051022, refined optical astrometry
  45. Chandra Observations of GRB 051022
  46. GRB051012: Swift-XRT analysis
  47. GRB 051022 Chandra Observations scheduled
  48. GRB051021B: Swift XRT refined analysis
  49. GRB051021a: optical observations
  50. GRB 051022: WSRT Radio Detection
  51. GRB 051022, mm counterpart
  52. GRB051022: host galaxy redshift
  53. GRB 051022: Swift/UVOT Upper Limits
  54. GRB051022: Radio Counterpart
  55. GRB051022: IR observations
  56. GRB 051022: SOAR JKs Observations
  57. GRB051021A: Swift XRT refined analysis
  58. Konus-Wind observation of GRB 051022
  59. GRB051022: Optical Observations
  60. GRB 051022: Magellan NIR imaging
  61. GRB 051021: PROMPT RcIc Observations
  62. GRB051021b: Magellan IR Imaging
  63. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  64. GRB 051021: Correction
  65. GRB 051022, J & K-band observation
  66. GRB 051021, SMARTS optical/IR observations
  67. GRB051022: Swift XRT Position
  68. GRB 051021: P200 Ks Observations
  69. IPN triangulation of GRB051022 (=H3950)
  70. GRB 051021: MDM Upper Limit
  71. GRB 051022 (=H3950): SXC Flight Localization is Valid
  72. GRB051021: Swift/UVOT Upper Limits
  73. GRB 051021B: Refined analysis of the Swift-BAT burst
  74. GRB 051022: SSO40 Optical Observations
  75. GRB051022,optical observation
  76. GRB 051022A: ROTSE-III Optical Limits
  77. GRB051022 (=H3590), A GRB Detected By HETE
  78. GRB 051022: Optical observations
  79. GRB 051021,optical observation
  80. GRB051021B: Swift XRT Position
  81. GRB 051021: SOAR NIR Observations
  82. GRB 051021B: Swift detection of a burst
  83. GRB051021: Swift XRT analysis
  84. GRB051021 (=H3947): Refined Analysis
  85. GRB 051021 : optical afterglow observation at Lulin
  86. GRB 051021: Optical observations
  87. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  88. GRB 051021: Optical observations and candidate afterglow
  89. GRB051021.63
  90. GRB051021.6: MASTER optical observation
  91. Swift-BAT trigger 160640 is not a real GRB
  92. GRB051021: A GRB Localized by HETE
  93. Swift-BAT trigger 160619 is not a GRB
  94. Swift-BAT triggered on a posible CR Shower or possible GRB
  95. GRB 050502b: Optical limit
  96. GRB 051016b: Optical limit
  97. Afterglow candidate of GRB 051016B observed at Lulin
  98. GRB 051016b: Gemini Near IR Observations
  99. GRB 051016A: Swift/UVOT upper limits
  100. GRB 051016B: refined analysis of the Swift/XRT data

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