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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').
  1. GRB 051022A: ROTSE-III Optical Limits
  2. GRB051022 (=H3590), A GRB Detected By HETE
  3. GRB 051022: Optical observations
  4. GRB 051021,optical observation
  5. GRB051021B: Swift XRT Position
  6. GRB 051021: SOAR NIR Observations
  7. GRB 051021B: Swift detection of a burst
  8. GRB051021: Swift XRT analysis
  9. GRB051021 (=H3947): Refined Analysis
  10. GRB 051021 : optical afterglow observation at Lulin
  11. GRB 051021: Optical observations
  12. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  13. GRB 051021: Optical observations and candidate afterglow
  14. GRB051021.63
  15. GRB051021.6: MASTER optical observation
  16. Swift-BAT trigger 160640 is not a real GRB
  17. GRB051021: A GRB Localized by HETE
  18. Swift-BAT trigger 160619 is not a GRB
  19. Swift-BAT triggered on a posible CR Shower or possible GRB
  20. GRB 050502b: Optical limit
  21. GRB 051016b: Optical limit
  22. Afterglow candidate of GRB 051016B observed at Lulin
  23. GRB 051016b: Gemini Near IR Observations
  24. GRB 051016A: Swift/UVOT upper limits
  25. GRB 051016B: refined analysis of the Swift/XRT data
  26. GRB 051016B: Swift/UVOT detection
  27. GRB 051016B,optical observation
  28. GRB 051016B : Optical follow-up at Lulin
  29. GRB 051016B: Refined analysis of the Swift-BAT burst
  30. GRB 051016B: Swift detection of a soft burst
  31. GRB 051016: Swift-BAT refined analysis
  32. GRB051016 XMM-Newton observation
  33. GRB051016: Swift XRT refined analysis.
  34. GRB051016: Planned XMM-Newton observation
  35. GRB 051016: LCO optical and near-IR imaging
  36. GRB 051016: PROMPT Observations
  37. GRB051016: Swift detection of a burst
  38. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  39. GRB051006: optical observations
  40. GRB 051012: Swift-BAT detection of burst yesterday
  41. Swift trigger 159578 is not a burst
  42. Swift-BAT Trigger 159578 is a possible burst
  43. GRB050805A: Rc optical observations
  44. GRB 051006: Swift/UVOT Upper Limits
  45. IBAS Alert 2675 : not a GRB
  46. GRB051008: optical candidate
  47. GRB 051008: - a high redshift high-luminosity burst?
  48. GRB 051008 - a low redshift low-luminosity burst?
  49. IBAS Alert 2673: not a real GRB
  50. GRB051011: bright nebulae near error box
  51. GRB051011: MASTER optical observation
  52. GRB051008: optical observation
  53. GRB051008: Swift XRT refined analysis
  54. GRB051008 - Swift UVOT upper limits
  55. Konus-Wind observation of GRB 051008
  56. GRB051008: Final refined analysis of the Swift-BAT burst
  57. GRB 051008: R-band upper limit
  58. GRB051008: Refined analysis of the Swift-BAT burst
  59. GRB051008: Radio Observation
  60. GRB 051008: Swift XRT position
  61. GRB 051008, optical observations
  62. GRB 051008: early Swift XRT analysis
  63. GRB 051008: Swift UVOT Candidate
  64. GRB051008: Swift-BAT detection of a bright burst
  65. GRB 051006: P60 Observations
  66. grb test
  67. GRB 051006: XRT refined analysis
  68. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  69. GRB 051006: optical observations at Sierra Nevada
  70. GRB051006: Refined analysis of the Swift-BAT burst
  71. GRB 051006: XRT position
  72. GRB051006: Swift detection of a burst
  73. GRB 050906, summary of radio observations
  74. Swift-BAT triggers 158261 and 158262 Retraction
  75. GRB051001: Swift UVOT Upper Limits
  76. GRB 050925: Second Epoch WSRT Radio Observations
  77. GRB 051001: Swift XRT refined analysis
  78. GRB 051001, optical observations at Mt. John
  79. GRB 051001: I-band limit
  80. GRB 051001: AAT infra-red observations
  81. GRB 051001: Swift-BAT refined analysis
  82. GRB 051001: Swift Detection of a Burst
  83. GRB 051001: ROTSE-III Optical Limits
  84. GRB050908: optical observations
  85. GRB050922C: optical observation
  86. GRB050922B: optical limit
  87. GRB 050922C: further VLT observations
  88. GRB 050820A: NIR photometry at the TNG
  89. GRB050922C: UVES/VLT high resolution spectroscopy
  90. GRB050925: Swift/XRT limits
  91. GRB/SGR 050925: IR Observations
  92. GRB050922C - Swift UVOT preliminary analysis
  93. GRB 050922C: break in the lightcurve
  94. GRB 050925: WSRT Radio Observations
  95. GRB050925: Swift UVOT upper limits
  96. Refined analysis of the Swift-BAT soft short burst
  97. GRB 050925 : I-band observation at Xinglong observatory
  98. GRB050925: Faulkes Telescope North R-band limit
  99. GRB050925: Swift-BAT detection of a short burst
  100. GRB 050922B: Correction to BAT refined analysis, longer burst

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