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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. GRB050709: Second Epoch Chandra Observation
  2. GRB 050724: dust-scattered X-ray halo detected in SWIFT/XRT observation
  3. GRB050724: Further Radio Observations
  4. GRB 050726: early Swift XRT analysis results
  5. GRB050726: Swift-BAT detection of a weak burst
  6. GRB 050724: Optical Variability in Nearby Galaxy
  7. GRB 050724: J-band observations
  8. GRB 050724: GMOS Imaging and Spectroscopy
  9. GRB 050724: SWIFT XRT refined position
  10. RXTE ASM Detection of GRB050724
  11. GRB050724: Radio Observation
  12. GRB 050724: spectroscopy of object in the XRT error circle
  13. GRB 050724: Optical limit
  14. GRB 050724: optical and near-IR observations
  15. GRB 050724: Optical imaging/astrometry
  16. GRB 050724: RTT150 optical observations
  17. GRB 050724: Swift/UVOT Upper Limit
  18. GRB 050724: early Swift XRT analysis results
  19. GRB 050724 : Lulin early R-band monitoring observations
  20. GRB050724: Refined analysis of the Swift-BAT possible short burst
  21. GRB 050724: possible host galaxy in DSS
  22. GRB050724: a short-burst detected by Swift
  23. Swift-BAT trigger 147325 is not due to a real GRB
  24. GRB050723: XRT distributed coordinates are not related to the burst
  25. GRB 050721: early afterglow light curve
  26. GRB 050721A: Swift-BAT refined analysis
  27. Correction to GCN Circ 3474 on GRB050525A
  28. GRB 050721A: Early Swift XRT analysis results
  29. GRB050721A: optical decay
  30. GRB 050721: optical afterglow confirmed
  31. Swift BAT Trigger 146986 is SWIFT J1753.5-0127
  32. GRB 050721a: Optical Observations
  33. GRB050721A: Swift-BAT detection of a weak burst
  34. GRB 050709: Refined Spectral and Temporal Properties
  35. GRB 050717: PROMPT RcIc Observations
  36. GRB050714b: Radio Observation
  37. GRB050712: Radio Observations
  38. GRB 050714a: Refined XRT analysis and afterglow confirmation
  39. GRB050713a: Radio Observation
  40. Swift-BAT trigger 146731 is not a real GRB
  41. GRB 050712, Tautenburg optical afterglow observations
  42. Swift-BAT detection of a possible GRB
  43. GRB 050714B: VLT R-band observations
  44. GRB 050717: Additional LCO observations
  45. GRB050717
  46. GRB 050716; J-band observations
  47. Konus-Wind observation of GRB 050717
  48. GRB 050717: LCO near-IR observations
  49. Swift/UVOT Observations of GRB 050717
  50. GRB 050717: Swift-BAT refined analysis
  51. GRB 050717: Refined XRT analysis.
  52. GRB050712: optical limits
  53. GRB050717: Swift XRT position
  54. Swift detection of GRB 050717
  55. GRB 050716 - UKIRT identification of candidate afterglow
  56. Swift UVOT Observations of GRB 050716
  57. GRB 050716: Refined XRT analysis.
  58. GRB050716: Refined analysis of the Swift-BAT burst
  59. GRB 050716: Lulin B and R band optical observations
  60. GRB050716, optical observation
  61. GRB 050716: Optical Observations
  62. GRB050716: Faulkes North Telescope observation
  63. GRB050716: Correction to sign in XRT coordinate
  64. Swift/BAT detection of GRB 050716
  65. GRB050715: Refined analysis of the Swift-BAT burst
  66. GRB 050715: Swift-BAT detection
  67. Swift UVOT Observations of GRB 050714B
  68. Konus-Wind observation of GRB 050713A
  69. GRB 050714B: refined XRT analysis
  70. GRB 050713b: RTT150 optical observations
  71. GRB 050714B: candidate afterglow does not fade
  72. GRB050714B: Refined analysis of the Swift-BAT burst
  73. GRB 050714B: optical afterglow
  74. Swift detection of a long transient (GRB 050714B?)
  75. GRB 050709: optical afterglow candidate
  76. GRB 050714, R-band candidate
  77. GRB 050714: Swift XRT afterglow position
  78. GRB 050714, optical observations
  79. GRB 050714A: ROTSE-III Optical Limits
  80. GRB 050714 - A long GRB detected with INTEGRAL
  81. GRB 050713A: XRT refined analysis
  82. GRB 050709: Spectroscopy
  83. GRB 050713A: RAPTOR detection of early optical emission
  84. GRB050713B :Swift/UVOT observations
  85. GRB050713b: XRT refined analysis
  86. GRB050712: TNG R-band observations
  87. GRB 050713B: Swift-BAT Refined Analysis
  88. Swift-BAT Trigger 145729 is not a GRB
  89. GRB 050713A: Swift/UVOT observation
  90. GRB 050713A : Swift-BAT Refined Analysis
  91. GRB050712: Swift UVOT Observation of Afterglow Emission
  92. GRB 050713A : Lulin R-band observation
  93. GRB 050713A XMM-Newton observation
  94. GRB 050713b : Lulin R-band observations
  95. GRB050713B: Faulkes North Telescope observation
  96. RBO RI observations of GRB 050713A
  97. GRB 050713B
  98. GRB050709 : Chandra source optical counterpart
  99. GRB050713: Liverpool Telescope prompt observations
  100. GRB 050712, optical observations

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