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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. IPN triangulation of GRB051022 (=H3950)
  2. GRB 051021: MDM Upper Limit
  3. GRB 051022 (=H3950): SXC Flight Localization is Valid
  4. GRB051021: Swift/UVOT Upper Limits
  5. GRB 051021B: Refined analysis of the Swift-BAT burst
  6. GRB 051022: SSO40 Optical Observations
  7. GRB051022,optical observation
  8. GRB 051022A: ROTSE-III Optical Limits
  9. GRB051022 (=H3590), A GRB Detected By HETE
  10. GRB 051022: Optical observations
  11. GRB 051021,optical observation
  12. GRB051021B: Swift XRT Position
  13. GRB 051021: SOAR NIR Observations
  14. GRB 051021B: Swift detection of a burst
  15. GRB051021: Swift XRT analysis
  16. GRB051021 (=H3947): Refined Analysis
  17. GRB 051021 : optical afterglow observation at Lulin
  18. GRB 051021: Optical observations
  19. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  20. GRB 051021: Optical observations and candidate afterglow
  21. GRB051021.63
  22. GRB051021.6: MASTER optical observation
  23. Swift-BAT trigger 160640 is not a real GRB
  24. GRB051021: A GRB Localized by HETE
  25. Swift-BAT trigger 160619 is not a GRB
  26. Swift-BAT triggered on a posible CR Shower or possible GRB
  27. GRB 050502b: Optical limit
  28. GRB 051016b: Optical limit
  29. Afterglow candidate of GRB 051016B observed at Lulin
  30. GRB 051016b: Gemini Near IR Observations
  31. GRB 051016A: Swift/UVOT upper limits
  32. GRB 051016B: refined analysis of the Swift/XRT data
  33. GRB 051016B: Swift/UVOT detection
  34. GRB 051016B,optical observation
  35. GRB 051016B : Optical follow-up at Lulin
  36. GRB 051016B: Refined analysis of the Swift-BAT burst
  37. GRB 051016B: Swift detection of a soft burst
  38. GRB 051016: Swift-BAT refined analysis
  39. GRB051016 XMM-Newton observation
  40. GRB051016: Swift XRT refined analysis.
  41. GRB051016: Planned XMM-Newton observation
  42. GRB 051016: LCO optical and near-IR imaging
  43. GRB 051016: PROMPT Observations
  44. GRB051016: Swift detection of a burst
  45. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  46. GRB051006: optical observations
  47. GRB 051012: Swift-BAT detection of burst yesterday
  48. Swift trigger 159578 is not a burst
  49. Swift-BAT Trigger 159578 is a possible burst
  50. GRB050805A: Rc optical observations
  51. GRB 051006: Swift/UVOT Upper Limits
  52. IBAS Alert 2675 : not a GRB
  53. GRB051008: optical candidate
  54. GRB 051008: - a high redshift high-luminosity burst?
  55. GRB 051008 - a low redshift low-luminosity burst?
  56. IBAS Alert 2673: not a real GRB
  57. GRB051011: bright nebulae near error box
  58. GRB051011: MASTER optical observation
  59. GRB051008: optical observation
  60. GRB051008: Swift XRT refined analysis
  61. GRB051008 - Swift UVOT upper limits
  62. Konus-Wind observation of GRB 051008
  63. GRB051008: Final refined analysis of the Swift-BAT burst
  64. GRB 051008: R-band upper limit
  65. GRB051008: Refined analysis of the Swift-BAT burst
  66. GRB051008: Radio Observation
  67. GRB 051008: Swift XRT position
  68. GRB 051008, optical observations
  69. GRB 051008: early Swift XRT analysis
  70. GRB 051008: Swift UVOT Candidate
  71. GRB051008: Swift-BAT detection of a bright burst
  72. GRB 051006: P60 Observations
  73. grb test
  74. GRB 051006: XRT refined analysis
  75. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  76. GRB 051006: optical observations at Sierra Nevada
  77. GRB051006: Refined analysis of the Swift-BAT burst
  78. GRB 051006: XRT position
  79. GRB051006: Swift detection of a burst
  80. GRB 050906, summary of radio observations
  81. Swift-BAT triggers 158261 and 158262 Retraction
  82. GRB051001: Swift UVOT Upper Limits
  83. GRB 050925: Second Epoch WSRT Radio Observations
  84. GRB 051001: Swift XRT refined analysis
  85. GRB 051001, optical observations at Mt. John
  86. GRB 051001: I-band limit
  87. GRB 051001: AAT infra-red observations
  88. GRB 051001: Swift-BAT refined analysis
  89. GRB 051001: Swift Detection of a Burst
  90. GRB 051001: ROTSE-III Optical Limits
  91. GRB050908: optical observations
  92. GRB050922C: optical observation
  93. GRB050922B: optical limit
  94. GRB 050922C: further VLT observations
  95. GRB 050820A: NIR photometry at the TNG
  96. GRB050922C: UVES/VLT high resolution spectroscopy
  97. GRB050925: Swift/XRT limits
  98. GRB/SGR 050925: IR Observations
  99. GRB050922C - Swift UVOT preliminary analysis
  100. GRB 050922C: break in the lightcurve

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