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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. GCN 050801: early Swift XRT analysis results
  2. GRB 050801: Swift-BAT refined analysis
  3. GRB 050801, SMARTS optical/IR afterglow observations
  4. GRB 050801, afterglow observations
  5. GRB 050730, corrected photometry and break?
  6. GRB 050801: ROTSE-III Early Afterglow Break
  7. GRB050801: Swift-BAT detection of a burst
  8. GRB050801: GCN XRT position is incorrect
  9. GRB 050801: ROTSE-III Detection of Possible Counterpart
  10. GRB 050730: XRT refined analysis
  11. Correction to GCN Circ 3476 on GRB050525A
  12. GRB 050730: early TAROT optical observations
  13. GRB 050726: PROMPT Rc Observations
  14. GRB 050730: RTT150 optical observations
  15. Swift/UVOT photometry of GRB050730
  16. GRB 050730, spectra and optical photometry
  17. GRB050730: Refined BAT analysis of the Swift-BAT burst
  18. GRB 050730: Swift XRT afterglow observations
  19. GRB 050730 XMM-Newton observation
  20. GRB 050730: PROMPT VRcIc Observations
  21. GRB050730, afterglow observations
  22. GRB050730: confirmation of redshift
  23. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  24. GRB 050730, SMARTS optical/IR afterglow observations
  25. GRB 050730 : Planned XMM-Newton observation
  26. GRB050730: Liverpool Telescope optical observations
  27. GRB 050730, optical candidate
  28. GRB050730: Swift-BAT detection of a weak burst
  29. GRB 050713A: Swift XRT extended light curve
  30. GRB 050709: PROMPT Rc Observations
  31. GRB050713b: Maidanak optical observations
  32. GRB 050724: Secure Host Redshift from Keck
  33. GRB 050724: WHT optical observations
  34. GRB050726: Swift UVOT observations
  35. GRB 050724: Chandra Observations of the X-ray Afterglow
  36. GRB050724: Refined Radio Position
  37. GRB050713: analysis of the XMM-Newton observation
  38. GRB 050724, SMARTS optical/IR afterglow observations
  39. GRB 050726, SMARTS optical/IR observations
  40. Swift-BAT trigger 147918 is not a real GRB
  41. GRB 050727: RTT150 optical observations
  42. GRB050724: VLT observations of the variable source
  43. GRB050727: KAIT optical limit
  44. GRB050709: Second Epoch Chandra Observation
  45. GRB 050726: PROMPT Rc Observations
  46. GRB050709: Second Epoch Chandra Observation
  47. GRB 050724: dust-scattered X-ray halo detected in SWIFT/XRT observation
  48. GRB050724: Further Radio Observations
  49. GRB 050726: early Swift XRT analysis results
  50. GRB050726: Swift-BAT detection of a weak burst
  51. GRB 050724: Optical Variability in Nearby Galaxy
  52. GRB 050724: J-band observations
  53. GRB 050724: GMOS Imaging and Spectroscopy
  54. GRB 050724: SWIFT XRT refined position
  55. RXTE ASM Detection of GRB050724
  56. GRB050724: Radio Observation
  57. GRB 050724: spectroscopy of object in the XRT error circle
  58. GRB 050724: Optical limit
  59. GRB 050724: optical and near-IR observations
  60. GRB 050724: Optical imaging/astrometry
  61. GRB 050724: RTT150 optical observations
  62. GRB 050724: Swift/UVOT Upper Limit
  63. GRB 050724: early Swift XRT analysis results
  64. GRB 050724 : Lulin early R-band monitoring observations
  65. GRB050724: Refined analysis of the Swift-BAT possible short burst
  66. GRB 050724: possible host galaxy in DSS
  67. GRB050724: a short-burst detected by Swift
  68. Swift-BAT trigger 147325 is not due to a real GRB
  69. GRB050723: XRT distributed coordinates are not related to the burst
  70. GRB 050721: early afterglow light curve
  71. GRB 050721A: Swift-BAT refined analysis
  72. Correction to GCN Circ 3474 on GRB050525A
  73. GRB 050721A: Early Swift XRT analysis results
  74. GRB050721A: optical decay
  75. GRB 050721: optical afterglow confirmed
  76. Swift BAT Trigger 146986 is SWIFT J1753.5-0127
  77. GRB 050721a: Optical Observations
  78. GRB050721A: Swift-BAT detection of a weak burst
  79. GRB 050709: Refined Spectral and Temporal Properties
  80. GRB 050717: PROMPT RcIc Observations
  81. GRB050714b: Radio Observation
  82. GRB050712: Radio Observations
  83. GRB 050714a: Refined XRT analysis and afterglow confirmation
  84. GRB050713a: Radio Observation
  85. Swift-BAT trigger 146731 is not a real GRB
  86. GRB 050712, Tautenburg optical afterglow observations
  87. Swift-BAT detection of a possible GRB
  88. GRB 050714B: VLT R-band observations
  89. GRB 050717: Additional LCO observations
  90. GRB050717
  91. GRB 050716; J-band observations
  92. Konus-Wind observation of GRB 050717
  93. GRB 050717: LCO near-IR observations
  94. Swift/UVOT Observations of GRB 050717
  95. GRB 050717: Swift-BAT refined analysis
  96. GRB 050717: Refined XRT analysis.
  97. GRB050712: optical limits
  98. GRB050717: Swift XRT position
  99. Swift detection of GRB 050717
  100. GRB 050716 - UKIRT identification of candidate afterglow

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