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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. SGR 1806-20: continued moderate activity seen with INTEGRAL
  2. GRB051021B: Swift/UVOT Upper limits
  3. GRB 051021, Optical Observations
  4. GRB 051022: XRT Refined Spectral and Temporal Analysis
  5. GRB 051022, refined optical astrometry
  6. Chandra Observations of GRB 051022
  7. GRB051012: Swift-XRT analysis
  8. GRB 051022 Chandra Observations scheduled
  9. GRB051021B: Swift XRT refined analysis
  10. GRB051021a: optical observations
  11. GRB 051022: WSRT Radio Detection
  12. GRB 051022, mm counterpart
  13. GRB051022: host galaxy redshift
  14. GRB 051022: Swift/UVOT Upper Limits
  15. GRB051022: Radio Counterpart
  16. GRB051022: IR observations
  17. GRB 051022: SOAR JKs Observations
  18. GRB051021A: Swift XRT refined analysis
  19. Konus-Wind observation of GRB 051022
  20. GRB051022: Optical Observations
  21. GRB 051022: Magellan NIR imaging
  22. GRB 051021: PROMPT RcIc Observations
  23. GRB051021b: Magellan IR Imaging
  24. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  25. GRB 051021: Correction
  26. GRB 051022, J & K-band observation
  27. GRB 051021, SMARTS optical/IR observations
  28. GRB051022: Swift XRT Position
  29. GRB 051021: P200 Ks Observations
  30. IPN triangulation of GRB051022 (=H3950)
  31. GRB 051021: MDM Upper Limit
  32. GRB 051022 (=H3950): SXC Flight Localization is Valid
  33. GRB051021: Swift/UVOT Upper Limits
  34. GRB 051021B: Refined analysis of the Swift-BAT burst
  35. GRB 051022: SSO40 Optical Observations
  36. GRB051022,optical observation
  37. GRB 051022A: ROTSE-III Optical Limits
  38. GRB051022 (=H3590), A GRB Detected By HETE
  39. GRB 051022: Optical observations
  40. GRB 051021,optical observation
  41. GRB051021B: Swift XRT Position
  42. GRB 051021: SOAR NIR Observations
  43. GRB 051021B: Swift detection of a burst
  44. GRB051021: Swift XRT analysis
  45. GRB051021 (=H3947): Refined Analysis
  46. GRB 051021 : optical afterglow observation at Lulin
  47. GRB 051021: Optical observations
  48. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  49. GRB 051021: Optical observations and candidate afterglow
  50. GRB051021.63
  51. GRB051021.6: MASTER optical observation
  52. Swift-BAT trigger 160640 is not a real GRB
  53. GRB051021: A GRB Localized by HETE
  54. Swift-BAT trigger 160619 is not a GRB
  55. Swift-BAT triggered on a posible CR Shower or possible GRB
  56. GRB 050502b: Optical limit
  57. GRB 051016b: Optical limit
  58. Afterglow candidate of GRB 051016B observed at Lulin
  59. GRB 051016b: Gemini Near IR Observations
  60. GRB 051016A: Swift/UVOT upper limits
  61. GRB 051016B: refined analysis of the Swift/XRT data
  62. GRB 051016B: Swift/UVOT detection
  63. GRB 051016B,optical observation
  64. GRB 051016B : Optical follow-up at Lulin
  65. GRB 051016B: Refined analysis of the Swift-BAT burst
  66. GRB 051016B: Swift detection of a soft burst
  67. GRB 051016: Swift-BAT refined analysis
  68. GRB051016 XMM-Newton observation
  69. GRB051016: Swift XRT refined analysis.
  70. GRB051016: Planned XMM-Newton observation
  71. GRB 051016: LCO optical and near-IR imaging
  72. GRB 051016: PROMPT Observations
  73. GRB051016: Swift detection of a burst
  74. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  75. GRB051006: optical observations
  76. GRB 051012: Swift-BAT detection of burst yesterday
  77. Swift trigger 159578 is not a burst
  78. Swift-BAT Trigger 159578 is a possible burst
  79. GRB050805A: Rc optical observations
  80. GRB 051006: Swift/UVOT Upper Limits
  81. IBAS Alert 2675 : not a GRB
  82. GRB051008: optical candidate
  83. GRB 051008: - a high redshift high-luminosity burst?
  84. GRB 051008 - a low redshift low-luminosity burst?
  85. IBAS Alert 2673: not a real GRB
  86. GRB051011: bright nebulae near error box
  87. GRB051011: MASTER optical observation
  88. GRB051008: optical observation
  89. GRB051008: Swift XRT refined analysis
  90. GRB051008 - Swift UVOT upper limits
  91. Konus-Wind observation of GRB 051008
  92. GRB051008: Final refined analysis of the Swift-BAT burst
  93. GRB 051008: R-band upper limit
  94. GRB051008: Refined analysis of the Swift-BAT burst
  95. GRB051008: Radio Observation
  96. GRB 051008: Swift XRT position
  97. GRB 051008, optical observations
  98. GRB 051008: early Swift XRT analysis
  99. GRB 051008: Swift UVOT Candidate
  100. GRB051008: Swift-BAT detection of a bright burst

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