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

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