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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 050802.422: Fading of the afterglow and detection of the host
  2. GRB050803: MASTER further analys
  3. GRB 050803, optical observations
  4. GRB 050803: Magellan Observations
  5. GRB 050803: early Swift XRT analysis results
  6. GRB 050803: TAROT optical limits
  7. GRB050803: MASTER optical observations
  8. GRB050802: Tentative absorption redshift
  9. GRB050803: Swift-BAT detection of a very long burst
  10. GCN GRB observation 050713A
  11. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  12. GRB 050802: Swift/UVOT optical and UV detections
  13. GRB050802: CrAO optical observations
  14. GRB050801: Unchanged decay slope
  15. GRB050802 radio non-detection
  16. GRB 050730: OHP optical observations
  17. GRB 050802: early Swift XRT analysis results
  18. GRB 050802: Swift/UVOT observations
  19. GRB 050802 : Lulin Optical follow-up observation
  20. GRB 050802: Swift-BAT refined analysis
  21. GRB050801: Optical photometry and decay index
  22. GRB 050802: XRT position
  23. GRB 050802: Swift Gamma-ray Burst
  24. GRB050801: Swift/UVOT Optical and UV detections
  25. GRB 050730: Preliminary Analysis of MIKE Spectrum
  26. GCN 050801: early Swift XRT analysis results
  27. GRB 050801: Swift-BAT refined analysis
  28. GRB 050801, SMARTS optical/IR afterglow observations
  29. GRB 050801, afterglow observations
  30. GRB 050730, corrected photometry and break?
  31. GRB 050801: ROTSE-III Early Afterglow Break
  32. GRB050801: Swift-BAT detection of a burst
  33. GRB050801: GCN XRT position is incorrect
  34. GRB 050801: ROTSE-III Detection of Possible Counterpart
  35. GRB 050730: XRT refined analysis
  36. Correction to GCN Circ 3476 on GRB050525A
  37. GRB 050730: early TAROT optical observations
  38. GRB 050726: PROMPT Rc Observations
  39. GRB 050730: RTT150 optical observations
  40. Swift/UVOT photometry of GRB050730
  41. GRB 050730, spectra and optical photometry
  42. GRB050730: Refined BAT analysis of the Swift-BAT burst
  43. GRB 050730: Swift XRT afterglow observations
  44. GRB 050730 XMM-Newton observation
  45. GRB 050730: PROMPT VRcIc Observations
  46. GRB050730, afterglow observations
  47. GRB050730: confirmation of redshift
  48. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  49. GRB 050730, SMARTS optical/IR afterglow observations
  50. GRB 050730 : Planned XMM-Newton observation
  51. GRB050730: Liverpool Telescope optical observations
  52. GRB 050730, optical candidate
  53. GRB050730: Swift-BAT detection of a weak burst
  54. GRB 050713A: Swift XRT extended light curve
  55. GRB 050709: PROMPT Rc Observations
  56. GRB050713b: Maidanak optical observations
  57. GRB 050724: Secure Host Redshift from Keck
  58. GRB 050724: WHT optical observations
  59. GRB050726: Swift UVOT observations
  60. GRB 050724: Chandra Observations of the X-ray Afterglow
  61. GRB050724: Refined Radio Position
  62. GRB050713: analysis of the XMM-Newton observation
  63. GRB 050724, SMARTS optical/IR afterglow observations
  64. GRB 050726, SMARTS optical/IR observations
  65. Swift-BAT trigger 147918 is not a real GRB
  66. GRB 050727: RTT150 optical observations
  67. GRB050724: VLT observations of the variable source
  68. GRB050727: KAIT optical limit
  69. GRB050709: Second Epoch Chandra Observation
  70. GRB 050726: PROMPT Rc Observations
  71. GRB050709: Second Epoch Chandra Observation
  72. GRB 050724: dust-scattered X-ray halo detected in SWIFT/XRT observation
  73. GRB050724: Further Radio Observations
  74. GRB 050726: early Swift XRT analysis results
  75. GRB050726: Swift-BAT detection of a weak burst
  76. GRB 050724: Optical Variability in Nearby Galaxy
  77. GRB 050724: J-band observations
  78. GRB 050724: GMOS Imaging and Spectroscopy
  79. GRB 050724: SWIFT XRT refined position
  80. RXTE ASM Detection of GRB050724
  81. GRB050724: Radio Observation
  82. GRB 050724: spectroscopy of object in the XRT error circle
  83. GRB 050724: Optical limit
  84. GRB 050724: optical and near-IR observations
  85. GRB 050724: Optical imaging/astrometry
  86. GRB 050724: RTT150 optical observations
  87. GRB 050724: Swift/UVOT Upper Limit
  88. GRB 050724: early Swift XRT analysis results
  89. GRB 050724 : Lulin early R-band monitoring observations
  90. GRB050724: Refined analysis of the Swift-BAT possible short burst
  91. GRB 050724: possible host galaxy in DSS
  92. GRB050724: a short-burst detected by Swift
  93. Swift-BAT trigger 147325 is not due to a real GRB
  94. GRB050723: XRT distributed coordinates are not related to the burst
  95. GRB 050721: early afterglow light curve
  96. GRB 050721A: Swift-BAT refined analysis
  97. Correction to GCN Circ 3474 on GRB050525A
  98. GRB 050721A: Early Swift XRT analysis results
  99. GRB050721A: optical decay
  100. GRB 050721: optical afterglow confirmed

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