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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. GRB051028: optical observations
  2. GRB051028: Swift/UVOT upper limits
  3. GRB051028: confirmation of the afterglow
  4. GRB051028: WHT optical candidate
  5. GRB051028: Swift XRT Position
  6. GRB051028:MASTER observations
  7. GRB 051028 (=H3951): A GRB localized by HETE
  8. GRB051028:MASTER optical observations
  9. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  10. GRB051022: Swift XRT measurement of jet break
  11. SGR 1806-20: continued moderate activity seen with INTEGRAL
  12. GRB051021B: Swift/UVOT Upper limits
  13. GRB 051021, Optical Observations
  14. GRB 051022: XRT Refined Spectral and Temporal Analysis
  15. GRB 051022, refined optical astrometry
  16. Chandra Observations of GRB 051022
  17. GRB051012: Swift-XRT analysis
  18. GRB 051022 Chandra Observations scheduled
  19. GRB051021B: Swift XRT refined analysis
  20. GRB051021a: optical observations
  21. GRB 051022: WSRT Radio Detection
  22. GRB 051022, mm counterpart
  23. GRB051022: host galaxy redshift
  24. GRB 051022: Swift/UVOT Upper Limits
  25. GRB051022: Radio Counterpart
  26. GRB051022: IR observations
  27. GRB 051022: SOAR JKs Observations
  28. GRB051021A: Swift XRT refined analysis
  29. Konus-Wind observation of GRB 051022
  30. GRB051022: Optical Observations
  31. GRB 051022: Magellan NIR imaging
  32. GRB 051021: PROMPT RcIc Observations
  33. GRB051021b: Magellan IR Imaging
  34. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  35. GRB 051021: Correction
  36. GRB 051022, J & K-band observation
  37. GRB 051021, SMARTS optical/IR observations
  38. GRB051022: Swift XRT Position
  39. GRB 051021: P200 Ks Observations
  40. IPN triangulation of GRB051022 (=H3950)
  41. GRB 051021: MDM Upper Limit
  42. GRB 051022 (=H3950): SXC Flight Localization is Valid
  43. GRB051021: Swift/UVOT Upper Limits
  44. GRB 051021B: Refined analysis of the Swift-BAT burst
  45. GRB 051022: SSO40 Optical Observations
  46. GRB051022,optical observation
  47. GRB 051022A: ROTSE-III Optical Limits
  48. GRB051022 (=H3590), A GRB Detected By HETE
  49. GRB 051022: Optical observations
  50. GRB 051021,optical observation
  51. GRB051021B: Swift XRT Position
  52. GRB 051021: SOAR NIR Observations
  53. GRB 051021B: Swift detection of a burst
  54. GRB051021: Swift XRT analysis
  55. GRB051021 (=H3947): Refined Analysis
  56. GRB 051021 : optical afterglow observation at Lulin
  57. GRB 051021: Optical observations
  58. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  59. GRB 051021: Optical observations and candidate afterglow
  60. GRB051021.63
  61. GRB051021.6: MASTER optical observation
  62. Swift-BAT trigger 160640 is not a real GRB
  63. GRB051021: A GRB Localized by HETE
  64. Swift-BAT trigger 160619 is not a GRB
  65. Swift-BAT triggered on a posible CR Shower or possible GRB
  66. GRB 050502b: Optical limit
  67. GRB 051016b: Optical limit
  68. Afterglow candidate of GRB 051016B observed at Lulin
  69. GRB 051016b: Gemini Near IR Observations
  70. GRB 051016A: Swift/UVOT upper limits
  71. GRB 051016B: refined analysis of the Swift/XRT data
  72. GRB 051016B: Swift/UVOT detection
  73. GRB 051016B,optical observation
  74. GRB 051016B : Optical follow-up at Lulin
  75. GRB 051016B: Refined analysis of the Swift-BAT burst
  76. GRB 051016B: Swift detection of a soft burst
  77. GRB 051016: Swift-BAT refined analysis
  78. GRB051016 XMM-Newton observation
  79. GRB051016: Swift XRT refined analysis.
  80. GRB051016: Planned XMM-Newton observation
  81. GRB 051016: LCO optical and near-IR imaging
  82. GRB 051016: PROMPT Observations
  83. GRB051016: Swift detection of a burst
  84. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  85. GRB051006: optical observations
  86. GRB 051012: Swift-BAT detection of burst yesterday
  87. Swift trigger 159578 is not a burst
  88. Swift-BAT Trigger 159578 is a possible burst
  89. GRB050805A: Rc optical observations
  90. GRB 051006: Swift/UVOT Upper Limits
  91. IBAS Alert 2675 : not a GRB
  92. GRB051008: optical candidate
  93. GRB 051008: - a high redshift high-luminosity burst?
  94. GRB 051008 - a low redshift low-luminosity burst?
  95. IBAS Alert 2673: not a real GRB
  96. GRB051011: bright nebulae near error box
  97. GRB051011: MASTER optical observation
  98. GRB051008: optical observation
  99. GRB051008: Swift XRT refined analysis
  100. GRB051008 - Swift UVOT upper limits

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