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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, SMARTS optical/IR observations
  2. GRB051022: Swift XRT Position
  3. GRB 051021: P200 Ks Observations
  4. IPN triangulation of GRB051022 (=H3950)
  5. GRB 051021: MDM Upper Limit
  6. GRB 051022 (=H3950): SXC Flight Localization is Valid
  7. GRB051021: Swift/UVOT Upper Limits
  8. GRB 051021B: Refined analysis of the Swift-BAT burst
  9. GRB 051022: SSO40 Optical Observations
  10. GRB051022,optical observation
  11. GRB 051022A: ROTSE-III Optical Limits
  12. GRB051022 (=H3590), A GRB Detected By HETE
  13. GRB 051022: Optical observations
  14. GRB 051021,optical observation
  15. GRB051021B: Swift XRT Position
  16. GRB 051021: SOAR NIR Observations
  17. GRB 051021B: Swift detection of a burst
  18. GRB051021: Swift XRT analysis
  19. GRB051021 (=H3947): Refined Analysis
  20. GRB 051021 : optical afterglow observation at Lulin
  21. GRB 051021: Optical observations
  22. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  23. GRB 051021: Optical observations and candidate afterglow
  24. GRB051021.63
  25. GRB051021.6: MASTER optical observation
  26. Swift-BAT trigger 160640 is not a real GRB
  27. GRB051021: A GRB Localized by HETE
  28. Swift-BAT trigger 160619 is not a GRB
  29. Swift-BAT triggered on a posible CR Shower or possible GRB
  30. GRB 050502b: Optical limit
  31. GRB 051016b: Optical limit
  32. Afterglow candidate of GRB 051016B observed at Lulin
  33. GRB 051016b: Gemini Near IR Observations
  34. GRB 051016A: Swift/UVOT upper limits
  35. GRB 051016B: refined analysis of the Swift/XRT data
  36. GRB 051016B: Swift/UVOT detection
  37. GRB 051016B,optical observation
  38. GRB 051016B : Optical follow-up at Lulin
  39. GRB 051016B: Refined analysis of the Swift-BAT burst
  40. GRB 051016B: Swift detection of a soft burst
  41. GRB 051016: Swift-BAT refined analysis
  42. GRB051016 XMM-Newton observation
  43. GRB051016: Swift XRT refined analysis.
  44. GRB051016: Planned XMM-Newton observation
  45. GRB 051016: LCO optical and near-IR imaging
  46. GRB 051016: PROMPT Observations
  47. GRB051016: Swift detection of a burst
  48. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  49. GRB051006: optical observations
  50. GRB 051012: Swift-BAT detection of burst yesterday
  51. Swift trigger 159578 is not a burst
  52. Swift-BAT Trigger 159578 is a possible burst
  53. GRB050805A: Rc optical observations
  54. GRB 051006: Swift/UVOT Upper Limits
  55. IBAS Alert 2675 : not a GRB
  56. GRB051008: optical candidate
  57. GRB 051008: - a high redshift high-luminosity burst?
  58. GRB 051008 - a low redshift low-luminosity burst?
  59. IBAS Alert 2673: not a real GRB
  60. GRB051011: bright nebulae near error box
  61. GRB051011: MASTER optical observation
  62. GRB051008: optical observation
  63. GRB051008: Swift XRT refined analysis
  64. GRB051008 - Swift UVOT upper limits
  65. Konus-Wind observation of GRB 051008
  66. GRB051008: Final refined analysis of the Swift-BAT burst
  67. GRB 051008: R-band upper limit
  68. GRB051008: Refined analysis of the Swift-BAT burst
  69. GRB051008: Radio Observation
  70. GRB 051008: Swift XRT position
  71. GRB 051008, optical observations
  72. GRB 051008: early Swift XRT analysis
  73. GRB 051008: Swift UVOT Candidate
  74. GRB051008: Swift-BAT detection of a bright burst
  75. GRB 051006: P60 Observations
  76. grb test
  77. GRB 051006: XRT refined analysis
  78. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  79. GRB 051006: optical observations at Sierra Nevada
  80. GRB051006: Refined analysis of the Swift-BAT burst
  81. GRB 051006: XRT position
  82. GRB051006: Swift detection of a burst
  83. GRB 050906, summary of radio observations
  84. Swift-BAT triggers 158261 and 158262 Retraction
  85. GRB051001: Swift UVOT Upper Limits
  86. GRB 050925: Second Epoch WSRT Radio Observations
  87. GRB 051001: Swift XRT refined analysis
  88. GRB 051001, optical observations at Mt. John
  89. GRB 051001: I-band limit
  90. GRB 051001: AAT infra-red observations
  91. GRB 051001: Swift-BAT refined analysis
  92. GRB 051001: Swift Detection of a Burst
  93. GRB 051001: ROTSE-III Optical Limits
  94. GRB050908: optical observations
  95. GRB050922C: optical observation
  96. GRB050922B: optical limit
  97. GRB 050922C: further VLT observations
  98. GRB 050820A: NIR photometry at the TNG
  99. GRB050922C: UVES/VLT high resolution spectroscopy
  100. GRB050925: Swift/XRT limits

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