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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 051016B host spectroscopy and redshift
  2. GRB051016B: optical observation
  3. Recent GRB UBVRcIc field photometry
  4. Konus-Wind observation of GRB 051028
  5. GRB051028:MASTER correction and final results
  6. GRB 051022: RTT150 optical observations
  7. GRB 051021A: RTT150 optical observations
  8. GRB051028 SARA Observation
  9. GRB051028: optical observations
  10. GRB051028: Swift/UVOT upper limits
  11. GRB051028: confirmation of the afterglow
  12. GRB051028: WHT optical candidate
  13. GRB051028: Swift XRT Position
  14. GRB051028:MASTER observations
  15. GRB 051028 (=H3951): A GRB localized by HETE
  16. GRB051028:MASTER optical observations
  17. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  18. GRB051022: Swift XRT measurement of jet break
  19. SGR 1806-20: continued moderate activity seen with INTEGRAL
  20. GRB051021B: Swift/UVOT Upper limits
  21. GRB 051021, Optical Observations
  22. GRB 051022: XRT Refined Spectral and Temporal Analysis
  23. GRB 051022, refined optical astrometry
  24. Chandra Observations of GRB 051022
  25. GRB051012: Swift-XRT analysis
  26. GRB 051022 Chandra Observations scheduled
  27. GRB051021B: Swift XRT refined analysis
  28. GRB051021a: optical observations
  29. GRB 051022: WSRT Radio Detection
  30. GRB 051022, mm counterpart
  31. GRB051022: host galaxy redshift
  32. GRB 051022: Swift/UVOT Upper Limits
  33. GRB051022: Radio Counterpart
  34. GRB051022: IR observations
  35. GRB 051022: SOAR JKs Observations
  36. GRB051021A: Swift XRT refined analysis
  37. Konus-Wind observation of GRB 051022
  38. GRB051022: Optical Observations
  39. GRB 051022: Magellan NIR imaging
  40. GRB 051021: PROMPT RcIc Observations
  41. GRB051021b: Magellan IR Imaging
  42. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  43. GRB 051021: Correction
  44. GRB 051022, J & K-band observation
  45. GRB 051021, SMARTS optical/IR observations
  46. GRB051022: Swift XRT Position
  47. GRB 051021: P200 Ks Observations
  48. IPN triangulation of GRB051022 (=H3950)
  49. GRB 051021: MDM Upper Limit
  50. GRB 051022 (=H3950): SXC Flight Localization is Valid
  51. GRB051021: Swift/UVOT Upper Limits
  52. GRB 051021B: Refined analysis of the Swift-BAT burst
  53. GRB 051022: SSO40 Optical Observations
  54. GRB051022,optical observation
  55. GRB 051022A: ROTSE-III Optical Limits
  56. GRB051022 (=H3590), A GRB Detected By HETE
  57. GRB 051022: Optical observations
  58. GRB 051021,optical observation
  59. GRB051021B: Swift XRT Position
  60. GRB 051021: SOAR NIR Observations
  61. GRB 051021B: Swift detection of a burst
  62. GRB051021: Swift XRT analysis
  63. GRB051021 (=H3947): Refined Analysis
  64. GRB 051021 : optical afterglow observation at Lulin
  65. GRB 051021: Optical observations
  66. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  67. GRB 051021: Optical observations and candidate afterglow
  68. GRB051021.63
  69. GRB051021.6: MASTER optical observation
  70. Swift-BAT trigger 160640 is not a real GRB
  71. GRB051021: A GRB Localized by HETE
  72. Swift-BAT trigger 160619 is not a GRB
  73. Swift-BAT triggered on a posible CR Shower or possible GRB
  74. GRB 050502b: Optical limit
  75. GRB 051016b: Optical limit
  76. Afterglow candidate of GRB 051016B observed at Lulin
  77. GRB 051016b: Gemini Near IR Observations
  78. GRB 051016A: Swift/UVOT upper limits
  79. GRB 051016B: refined analysis of the Swift/XRT data
  80. GRB 051016B: Swift/UVOT detection
  81. GRB 051016B,optical observation
  82. GRB 051016B : Optical follow-up at Lulin
  83. GRB 051016B: Refined analysis of the Swift-BAT burst
  84. GRB 051016B: Swift detection of a soft burst
  85. GRB 051016: Swift-BAT refined analysis
  86. GRB051016 XMM-Newton observation
  87. GRB051016: Swift XRT refined analysis.
  88. GRB051016: Planned XMM-Newton observation
  89. GRB 051016: LCO optical and near-IR imaging
  90. GRB 051016: PROMPT Observations
  91. GRB051016: Swift detection of a burst
  92. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  93. GRB051006: optical observations
  94. GRB 051012: Swift-BAT detection of burst yesterday
  95. Swift trigger 159578 is not a burst
  96. Swift-BAT Trigger 159578 is a possible burst
  97. GRB050805A: Rc optical observations
  98. GRB 051006: Swift/UVOT Upper Limits
  99. IBAS Alert 2675 : not a GRB
  100. GRB051008: optical candidate

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