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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 050803: PROMPT BVRcIc Observations
  2. GRB 050807: ROTSE-III Optical Limits
  3. GRB 050730, optical observation
  4. GRB050805b: CrAO optical limit
  5. GRB050805a : Null detection report
  6. GRB050730, optical observations
  7. GRB050803, optical observations
  8. Swift-BAT trigger 149118 is very likely not a GRB
  9. Retraction of Swift Trigger 149131 (GRB 050805B)
  10. GRB 050805b: OHP optical limits
  11. GRB 050805b: TAROT optical limits
  12. GRB050805b: MASTER optical observations
  13. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  14. GRB050805a: MASTER optical candidat
  15. Swift-BAT trigger 149118 is probably not a GRB
  16. GRB050802: TNG optical observations
  17. GRB050803: Radio Observation
  18. GRB 050803: RTT150 optical observations
  19. GRB050801: Radio Observation
  20. GRB050730: Radio Detection
  21. GRB050803: CrAO optical observations, possible OT candidate
  22. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  23. GRB 050803: Keck Observations
  24. GRB 050803: Swift-BAT refined analysis
  25. GRB 050802.422: Fading of the afterglow and detection of the host
  26. GRB050803: MASTER further analys
  27. GRB 050803, optical observations
  28. GRB 050803: Magellan Observations
  29. GRB 050803: early Swift XRT analysis results
  30. GRB 050803: TAROT optical limits
  31. GRB050803: MASTER optical observations
  32. GRB050802: Tentative absorption redshift
  33. GRB050803: Swift-BAT detection of a very long burst
  34. GCN GRB observation 050713A
  35. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  36. GRB 050802: Swift/UVOT optical and UV detections
  37. GRB050802: CrAO optical observations
  38. GRB050801: Unchanged decay slope
  39. GRB050802 radio non-detection
  40. GRB 050730: OHP optical observations
  41. GRB 050802: early Swift XRT analysis results
  42. GRB 050802: Swift/UVOT observations
  43. GRB 050802 : Lulin Optical follow-up observation
  44. GRB 050802: Swift-BAT refined analysis
  45. GRB050801: Optical photometry and decay index
  46. GRB 050802: XRT position
  47. GRB 050802: Swift Gamma-ray Burst
  48. GRB050801: Swift/UVOT Optical and UV detections
  49. GRB 050730: Preliminary Analysis of MIKE Spectrum
  50. GCN 050801: early Swift XRT analysis results
  51. GRB 050801: Swift-BAT refined analysis
  52. GRB 050801, SMARTS optical/IR afterglow observations
  53. GRB 050801, afterglow observations
  54. GRB 050730, corrected photometry and break?
  55. GRB 050801: ROTSE-III Early Afterglow Break
  56. GRB050801: Swift-BAT detection of a burst
  57. GRB050801: GCN XRT position is incorrect
  58. GRB 050801: ROTSE-III Detection of Possible Counterpart
  59. GRB 050730: XRT refined analysis
  60. Correction to GCN Circ 3476 on GRB050525A
  61. GRB 050730: early TAROT optical observations
  62. GRB 050726: PROMPT Rc Observations
  63. GRB 050730: RTT150 optical observations
  64. Swift/UVOT photometry of GRB050730
  65. GRB 050730, spectra and optical photometry
  66. GRB050730: Refined BAT analysis of the Swift-BAT burst
  67. GRB 050730: Swift XRT afterglow observations
  68. GRB 050730 XMM-Newton observation
  69. GRB 050730: PROMPT VRcIc Observations
  70. GRB050730, afterglow observations
  71. GRB050730: confirmation of redshift
  72. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  73. GRB 050730, SMARTS optical/IR afterglow observations
  74. GRB 050730 : Planned XMM-Newton observation
  75. GRB050730: Liverpool Telescope optical observations
  76. GRB 050730, optical candidate
  77. GRB050730: Swift-BAT detection of a weak burst
  78. GRB 050713A: Swift XRT extended light curve
  79. GRB 050709: PROMPT Rc Observations
  80. GRB050713b: Maidanak optical observations
  81. GRB 050724: Secure Host Redshift from Keck
  82. GRB 050724: WHT optical observations
  83. GRB050726: Swift UVOT observations
  84. GRB 050724: Chandra Observations of the X-ray Afterglow
  85. GRB050724: Refined Radio Position
  86. GRB050713: analysis of the XMM-Newton observation
  87. GRB 050724, SMARTS optical/IR afterglow observations
  88. GRB 050726, SMARTS optical/IR observations
  89. Swift-BAT trigger 147918 is not a real GRB
  90. GRB 050727: RTT150 optical observations
  91. GRB050724: VLT observations of the variable source
  92. GRB050727: KAIT optical limit
  93. GRB050709: Second Epoch Chandra Observation
  94. GRB 050726: PROMPT Rc Observations
  95. GRB050709: Second Epoch Chandra Observation
  96. GRB 050724: dust-scattered X-ray halo detected in SWIFT/XRT observation
  97. GRB050724: Further Radio Observations
  98. GRB 050726: early Swift XRT analysis results
  99. GRB050726: Swift-BAT detection of a weak burst
  100. GRB 050724: Optical Variability in Nearby Galaxy

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