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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. GRB051012: Swift-XRT analysis
  2. GRB 051022 Chandra Observations scheduled
  3. GRB051021B: Swift XRT refined analysis
  4. GRB051021a: optical observations
  5. GRB 051022: WSRT Radio Detection
  6. GRB 051022, mm counterpart
  7. GRB051022: host galaxy redshift
  8. GRB 051022: Swift/UVOT Upper Limits
  9. GRB051022: Radio Counterpart
  10. GRB051022: IR observations
  11. GRB 051022: SOAR JKs Observations
  12. GRB051021A: Swift XRT refined analysis
  13. Konus-Wind observation of GRB 051022
  14. GRB051022: Optical Observations
  15. GRB 051022: Magellan NIR imaging
  16. GRB 051021: PROMPT RcIc Observations
  17. GRB051021b: Magellan IR Imaging
  18. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  19. GRB 051021: Correction
  20. GRB 051022, J & K-band observation
  21. GRB 051021, SMARTS optical/IR observations
  22. GRB051022: Swift XRT Position
  23. GRB 051021: P200 Ks Observations
  24. IPN triangulation of GRB051022 (=H3950)
  25. GRB 051021: MDM Upper Limit
  26. GRB 051022 (=H3950): SXC Flight Localization is Valid
  27. GRB051021: Swift/UVOT Upper Limits
  28. GRB 051021B: Refined analysis of the Swift-BAT burst
  29. GRB 051022: SSO40 Optical Observations
  30. GRB051022,optical observation
  31. GRB 051022A: ROTSE-III Optical Limits
  32. GRB051022 (=H3590), A GRB Detected By HETE
  33. GRB 051022: Optical observations
  34. GRB 051021,optical observation
  35. GRB051021B: Swift XRT Position
  36. GRB 051021: SOAR NIR Observations
  37. GRB 051021B: Swift detection of a burst
  38. GRB051021: Swift XRT analysis
  39. GRB051021 (=H3947): Refined Analysis
  40. GRB 051021 : optical afterglow observation at Lulin
  41. GRB 051021: Optical observations
  42. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  43. GRB 051021: Optical observations and candidate afterglow
  44. GRB051021.63
  45. GRB051021.6: MASTER optical observation
  46. Swift-BAT trigger 160640 is not a real GRB
  47. GRB051021: A GRB Localized by HETE
  48. Swift-BAT trigger 160619 is not a GRB
  49. Swift-BAT triggered on a posible CR Shower or possible GRB
  50. GRB 050502b: Optical limit
  51. GRB 051016b: Optical limit
  52. Afterglow candidate of GRB 051016B observed at Lulin
  53. GRB 051016b: Gemini Near IR Observations
  54. GRB 051016A: Swift/UVOT upper limits
  55. GRB 051016B: refined analysis of the Swift/XRT data
  56. GRB 051016B: Swift/UVOT detection
  57. GRB 051016B,optical observation
  58. GRB 051016B : Optical follow-up at Lulin
  59. GRB 051016B: Refined analysis of the Swift-BAT burst
  60. GRB 051016B: Swift detection of a soft burst
  61. GRB 051016: Swift-BAT refined analysis
  62. GRB051016 XMM-Newton observation
  63. GRB051016: Swift XRT refined analysis.
  64. GRB051016: Planned XMM-Newton observation
  65. GRB 051016: LCO optical and near-IR imaging
  66. GRB 051016: PROMPT Observations
  67. GRB051016: Swift detection of a burst
  68. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  69. GRB051006: optical observations
  70. GRB 051012: Swift-BAT detection of burst yesterday
  71. Swift trigger 159578 is not a burst
  72. Swift-BAT Trigger 159578 is a possible burst
  73. GRB050805A: Rc optical observations
  74. GRB 051006: Swift/UVOT Upper Limits
  75. IBAS Alert 2675 : not a GRB
  76. GRB051008: optical candidate
  77. GRB 051008: - a high redshift high-luminosity burst?
  78. GRB 051008 - a low redshift low-luminosity burst?
  79. IBAS Alert 2673: not a real GRB
  80. GRB051011: bright nebulae near error box
  81. GRB051011: MASTER optical observation
  82. GRB051008: optical observation
  83. GRB051008: Swift XRT refined analysis
  84. GRB051008 - Swift UVOT upper limits
  85. Konus-Wind observation of GRB 051008
  86. GRB051008: Final refined analysis of the Swift-BAT burst
  87. GRB 051008: R-band upper limit
  88. GRB051008: Refined analysis of the Swift-BAT burst
  89. GRB051008: Radio Observation
  90. GRB 051008: Swift XRT position
  91. GRB 051008, optical observations
  92. GRB 051008: early Swift XRT analysis
  93. GRB 051008: Swift UVOT Candidate
  94. GRB051008: Swift-BAT detection of a bright burst
  95. GRB 051006: P60 Observations
  96. grb test
  97. GRB 051006: XRT refined analysis
  98. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  99. GRB 051006: optical observations at Sierra Nevada
  100. GRB051006: Refined analysis of the Swift-BAT burst

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