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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. GRB050805b: CrAO optical limit
  2. GRB050805a : Null detection report
  3. GRB050730, optical observations
  4. GRB050803, optical observations
  5. Swift-BAT trigger 149118 is very likely not a GRB
  6. Retraction of Swift Trigger 149131 (GRB 050805B)
  7. GRB 050805b: OHP optical limits
  8. GRB 050805b: TAROT optical limits
  9. GRB050805b: MASTER optical observations
  10. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  11. GRB050805a: MASTER optical candidat
  12. Swift-BAT trigger 149118 is probably not a GRB
  13. GRB050802: TNG optical observations
  14. GRB050803: Radio Observation
  15. GRB 050803: RTT150 optical observations
  16. GRB050801: Radio Observation
  17. GRB050730: Radio Detection
  18. GRB050803: CrAO optical observations, possible OT candidate
  19. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  20. GRB 050803: Keck Observations
  21. GRB 050803: Swift-BAT refined analysis
  22. GRB 050802.422: Fading of the afterglow and detection of the host
  23. GRB050803: MASTER further analys
  24. GRB 050803, optical observations
  25. GRB 050803: Magellan Observations
  26. GRB 050803: early Swift XRT analysis results
  27. GRB 050803: TAROT optical limits
  28. GRB050803: MASTER optical observations
  29. GRB050802: Tentative absorption redshift
  30. GRB050803: Swift-BAT detection of a very long burst
  31. GCN GRB observation 050713A
  32. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  33. GRB 050802: Swift/UVOT optical and UV detections
  34. GRB050802: CrAO optical observations
  35. GRB050801: Unchanged decay slope
  36. GRB050802 radio non-detection
  37. GRB 050730: OHP optical observations
  38. GRB 050802: early Swift XRT analysis results
  39. GRB 050802: Swift/UVOT observations
  40. GRB 050802 : Lulin Optical follow-up observation
  41. GRB 050802: Swift-BAT refined analysis
  42. GRB050801: Optical photometry and decay index
  43. GRB 050802: XRT position
  44. GRB 050802: Swift Gamma-ray Burst
  45. GRB050801: Swift/UVOT Optical and UV detections
  46. GRB 050730: Preliminary Analysis of MIKE Spectrum
  47. GCN 050801: early Swift XRT analysis results
  48. GRB 050801: Swift-BAT refined analysis
  49. GRB 050801, SMARTS optical/IR afterglow observations
  50. GRB 050801, afterglow observations
  51. GRB 050730, corrected photometry and break?
  52. GRB 050801: ROTSE-III Early Afterglow Break
  53. GRB050801: Swift-BAT detection of a burst
  54. GRB050801: GCN XRT position is incorrect
  55. GRB 050801: ROTSE-III Detection of Possible Counterpart
  56. GRB 050730: XRT refined analysis
  57. Correction to GCN Circ 3476 on GRB050525A
  58. GRB 050730: early TAROT optical observations
  59. GRB 050726: PROMPT Rc Observations
  60. GRB 050730: RTT150 optical observations
  61. Swift/UVOT photometry of GRB050730
  62. GRB 050730, spectra and optical photometry
  63. GRB050730: Refined BAT analysis of the Swift-BAT burst
  64. GRB 050730: Swift XRT afterglow observations
  65. GRB 050730 XMM-Newton observation
  66. GRB 050730: PROMPT VRcIc Observations
  67. GRB050730, afterglow observations
  68. GRB050730: confirmation of redshift
  69. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  70. GRB 050730, SMARTS optical/IR afterglow observations
  71. GRB 050730 : Planned XMM-Newton observation
  72. GRB050730: Liverpool Telescope optical observations
  73. GRB 050730, optical candidate
  74. GRB050730: Swift-BAT detection of a weak burst
  75. GRB 050713A: Swift XRT extended light curve
  76. GRB 050709: PROMPT Rc Observations
  77. GRB050713b: Maidanak optical observations
  78. GRB 050724: Secure Host Redshift from Keck
  79. GRB 050724: WHT optical observations
  80. GRB050726: Swift UVOT observations
  81. GRB 050724: Chandra Observations of the X-ray Afterglow
  82. GRB050724: Refined Radio Position
  83. GRB050713: analysis of the XMM-Newton observation
  84. GRB 050724, SMARTS optical/IR afterglow observations
  85. GRB 050726, SMARTS optical/IR observations
  86. Swift-BAT trigger 147918 is not a real GRB
  87. GRB 050727: RTT150 optical observations
  88. GRB050724: VLT observations of the variable source
  89. GRB050727: KAIT optical limit
  90. GRB050709: Second Epoch Chandra Observation
  91. GRB 050726: PROMPT Rc Observations
  92. GRB050709: Second Epoch Chandra Observation
  93. GRB 050724: dust-scattered X-ray halo detected in SWIFT/XRT observation
  94. GRB050724: Further Radio Observations
  95. GRB 050726: early Swift XRT analysis results
  96. GRB050726: Swift-BAT detection of a weak burst
  97. GRB 050724: Optical Variability in Nearby Galaxy
  98. GRB 050724: J-band observations
  99. GRB 050724: GMOS Imaging and Spectroscopy
  100. GRB 050724: SWIFT XRT refined position

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