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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 051021, Optical Observations
  2. GRB 051022: XRT Refined Spectral and Temporal Analysis
  3. GRB 051022, refined optical astrometry
  4. Chandra Observations of GRB 051022
  5. GRB051012: Swift-XRT analysis
  6. GRB 051022 Chandra Observations scheduled
  7. GRB051021B: Swift XRT refined analysis
  8. GRB051021a: optical observations
  9. GRB 051022: WSRT Radio Detection
  10. GRB 051022, mm counterpart
  11. GRB051022: host galaxy redshift
  12. GRB 051022: Swift/UVOT Upper Limits
  13. GRB051022: Radio Counterpart
  14. GRB051022: IR observations
  15. GRB 051022: SOAR JKs Observations
  16. GRB051021A: Swift XRT refined analysis
  17. Konus-Wind observation of GRB 051022
  18. GRB051022: Optical Observations
  19. GRB 051022: Magellan NIR imaging
  20. GRB 051021: PROMPT RcIc Observations
  21. GRB051021b: Magellan IR Imaging
  22. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  23. GRB 051021: Correction
  24. GRB 051022, J & K-band observation
  25. GRB 051021, SMARTS optical/IR observations
  26. GRB051022: Swift XRT Position
  27. GRB 051021: P200 Ks Observations
  28. IPN triangulation of GRB051022 (=H3950)
  29. GRB 051021: MDM Upper Limit
  30. GRB 051022 (=H3950): SXC Flight Localization is Valid
  31. GRB051021: Swift/UVOT Upper Limits
  32. GRB 051021B: Refined analysis of the Swift-BAT burst
  33. GRB 051022: SSO40 Optical Observations
  34. GRB051022,optical observation
  35. GRB 051022A: ROTSE-III Optical Limits
  36. GRB051022 (=H3590), A GRB Detected By HETE
  37. GRB 051022: Optical observations
  38. GRB 051021,optical observation
  39. GRB051021B: Swift XRT Position
  40. GRB 051021: SOAR NIR Observations
  41. GRB 051021B: Swift detection of a burst
  42. GRB051021: Swift XRT analysis
  43. GRB051021 (=H3947): Refined Analysis
  44. GRB 051021 : optical afterglow observation at Lulin
  45. GRB 051021: Optical observations
  46. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  47. GRB 051021: Optical observations and candidate afterglow
  48. GRB051021.63
  49. GRB051021.6: MASTER optical observation
  50. Swift-BAT trigger 160640 is not a real GRB
  51. GRB051021: A GRB Localized by HETE
  52. Swift-BAT trigger 160619 is not a GRB
  53. Swift-BAT triggered on a posible CR Shower or possible GRB
  54. GRB 050502b: Optical limit
  55. GRB 051016b: Optical limit
  56. Afterglow candidate of GRB 051016B observed at Lulin
  57. GRB 051016b: Gemini Near IR Observations
  58. GRB 051016A: Swift/UVOT upper limits
  59. GRB 051016B: refined analysis of the Swift/XRT data
  60. GRB 051016B: Swift/UVOT detection
  61. GRB 051016B,optical observation
  62. GRB 051016B : Optical follow-up at Lulin
  63. GRB 051016B: Refined analysis of the Swift-BAT burst
  64. GRB 051016B: Swift detection of a soft burst
  65. GRB 051016: Swift-BAT refined analysis
  66. GRB051016 XMM-Newton observation
  67. GRB051016: Swift XRT refined analysis.
  68. GRB051016: Planned XMM-Newton observation
  69. GRB 051016: LCO optical and near-IR imaging
  70. GRB 051016: PROMPT Observations
  71. GRB051016: Swift detection of a burst
  72. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  73. GRB051006: optical observations
  74. GRB 051012: Swift-BAT detection of burst yesterday
  75. Swift trigger 159578 is not a burst
  76. Swift-BAT Trigger 159578 is a possible burst
  77. GRB050805A: Rc optical observations
  78. GRB 051006: Swift/UVOT Upper Limits
  79. IBAS Alert 2675 : not a GRB
  80. GRB051008: optical candidate
  81. GRB 051008: - a high redshift high-luminosity burst?
  82. GRB 051008 - a low redshift low-luminosity burst?
  83. IBAS Alert 2673: not a real GRB
  84. GRB051011: bright nebulae near error box
  85. GRB051011: MASTER optical observation
  86. GRB051008: optical observation
  87. GRB051008: Swift XRT refined analysis
  88. GRB051008 - Swift UVOT upper limits
  89. Konus-Wind observation of GRB 051008
  90. GRB051008: Final refined analysis of the Swift-BAT burst
  91. GRB 051008: R-band upper limit
  92. GRB051008: Refined analysis of the Swift-BAT burst
  93. GRB051008: Radio Observation
  94. GRB 051008: Swift XRT position
  95. GRB 051008, optical observations
  96. GRB 051008: early Swift XRT analysis
  97. GRB 051008: Swift UVOT Candidate
  98. GRB051008: Swift-BAT detection of a bright burst
  99. GRB 051006: P60 Observations
  100. grb test

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