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

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