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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 051021: Correction
  2. GRB 051022, J & K-band observation
  3. GRB 051021, SMARTS optical/IR observations
  4. GRB051022: Swift XRT Position
  5. GRB 051021: P200 Ks Observations
  6. IPN triangulation of GRB051022 (=H3950)
  7. GRB 051021: MDM Upper Limit
  8. GRB 051022 (=H3950): SXC Flight Localization is Valid
  9. GRB051021: Swift/UVOT Upper Limits
  10. GRB 051021B: Refined analysis of the Swift-BAT burst
  11. GRB 051022: SSO40 Optical Observations
  12. GRB051022,optical observation
  13. GRB 051022A: ROTSE-III Optical Limits
  14. GRB051022 (=H3590), A GRB Detected By HETE
  15. GRB 051022: Optical observations
  16. GRB 051021,optical observation
  17. GRB051021B: Swift XRT Position
  18. GRB 051021: SOAR NIR Observations
  19. GRB 051021B: Swift detection of a burst
  20. GRB051021: Swift XRT analysis
  21. GRB051021 (=H3947): Refined Analysis
  22. GRB 051021 : optical afterglow observation at Lulin
  23. GRB 051021: Optical observations
  24. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  25. GRB 051021: Optical observations and candidate afterglow
  26. GRB051021.63
  27. GRB051021.6: MASTER optical observation
  28. Swift-BAT trigger 160640 is not a real GRB
  29. GRB051021: A GRB Localized by HETE
  30. Swift-BAT trigger 160619 is not a GRB
  31. Swift-BAT triggered on a posible CR Shower or possible GRB
  32. GRB 050502b: Optical limit
  33. GRB 051016b: Optical limit
  34. Afterglow candidate of GRB 051016B observed at Lulin
  35. GRB 051016b: Gemini Near IR Observations
  36. GRB 051016A: Swift/UVOT upper limits
  37. GRB 051016B: refined analysis of the Swift/XRT data
  38. GRB 051016B: Swift/UVOT detection
  39. GRB 051016B,optical observation
  40. GRB 051016B : Optical follow-up at Lulin
  41. GRB 051016B: Refined analysis of the Swift-BAT burst
  42. GRB 051016B: Swift detection of a soft burst
  43. GRB 051016: Swift-BAT refined analysis
  44. GRB051016 XMM-Newton observation
  45. GRB051016: Swift XRT refined analysis.
  46. GRB051016: Planned XMM-Newton observation
  47. GRB 051016: LCO optical and near-IR imaging
  48. GRB 051016: PROMPT Observations
  49. GRB051016: Swift detection of a burst
  50. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  51. GRB051006: optical observations
  52. GRB 051012: Swift-BAT detection of burst yesterday
  53. Swift trigger 159578 is not a burst
  54. Swift-BAT Trigger 159578 is a possible burst
  55. GRB050805A: Rc optical observations
  56. GRB 051006: Swift/UVOT Upper Limits
  57. IBAS Alert 2675 : not a GRB
  58. GRB051008: optical candidate
  59. GRB 051008: - a high redshift high-luminosity burst?
  60. GRB 051008 - a low redshift low-luminosity burst?
  61. IBAS Alert 2673: not a real GRB
  62. GRB051011: bright nebulae near error box
  63. GRB051011: MASTER optical observation
  64. GRB051008: optical observation
  65. GRB051008: Swift XRT refined analysis
  66. GRB051008 - Swift UVOT upper limits
  67. Konus-Wind observation of GRB 051008
  68. GRB051008: Final refined analysis of the Swift-BAT burst
  69. GRB 051008: R-band upper limit
  70. GRB051008: Refined analysis of the Swift-BAT burst
  71. GRB051008: Radio Observation
  72. GRB 051008: Swift XRT position
  73. GRB 051008, optical observations
  74. GRB 051008: early Swift XRT analysis
  75. GRB 051008: Swift UVOT Candidate
  76. GRB051008: Swift-BAT detection of a bright burst
  77. GRB 051006: P60 Observations
  78. grb test
  79. GRB 051006: XRT refined analysis
  80. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  81. GRB 051006: optical observations at Sierra Nevada
  82. GRB051006: Refined analysis of the Swift-BAT burst
  83. GRB 051006: XRT position
  84. GRB051006: Swift detection of a burst
  85. GRB 050906, summary of radio observations
  86. Swift-BAT triggers 158261 and 158262 Retraction
  87. GRB051001: Swift UVOT Upper Limits
  88. GRB 050925: Second Epoch WSRT Radio Observations
  89. GRB 051001: Swift XRT refined analysis
  90. GRB 051001, optical observations at Mt. John
  91. GRB 051001: I-band limit
  92. GRB 051001: AAT infra-red observations
  93. GRB 051001: Swift-BAT refined analysis
  94. GRB 051001: Swift Detection of a Burst
  95. GRB 051001: ROTSE-III Optical Limits
  96. GRB050908: optical observations
  97. GRB050922C: optical observation
  98. GRB050922B: optical limit
  99. GRB 050922C: further VLT observations
  100. GRB 050820A: NIR photometry at the TNG

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