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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. ATCA observations of SGR 1806-20
  2. SGR 1806-20, RHESSI observations of the 041227 giant flare
  3. Third epoch observations of SGR 1806-20 with VLA
  4. Second Epoch VLA observations of SGR 1806-20
  5. Second-epoch VLA observations of SGR 1806-20
  6. SGR1806: Detection of a Sudden Ionospheric Disturbance
  7. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  8. VLA observations of SGR 1806-20
  9. SGR1806 VLA Observations
  10. VLA observations of SGR 1806-20
  11. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  12. GRB 041217: Optical observations
  13. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  14. GRB041219, early time observations
  15. Detection of the SGR 1806-20 giant outburst back-scattered by the
  16. The giant outburst from SGR 1806-20
  17. IPN localization of giant flare from SGR1806-20
  18. Giant flare from SGR 1806-20 detected by INTEGRAL
  19. GRB041228: ROTSE-III Optical Observations
  20. GRB041228: Swift-BAT detection of a burst
  21. GRB041219; RXTE ASM Observations
  22. NIR Observations of GRB 041219
  23. GRB041226: ROTSE-III Optical Observations
  24. GRB041226: Swift-BAT detection of a burst
  25. GRB041223: decay of the afterglow
  26. GRB041224: ROTSE-III Optical Observations
  27. GRB 041224: near-infrared observations with REM
  28. GRB 041223: XRT afterglow spectrum and light curve
  29. GRB 041223 Fluence measured by Swift-BAT
  30. GRB041224: Swift-BAT detection of a soft burst
  31. GRB041223: optical and NIR observations with REM
  32. Swift-BAT Time History of GRB041219
  33. GRB 041219: TAROT optical observations
  34. GRB 041218: TAROT optical observations
  35. GRB 041223: J-band observations of the afterglow
  36. GRB 041223: Detection of Optical Transient with LCO40
  37. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  38. GRB 041219c: PROMPT Observations
  39. GRB041223: ROTSE-III Optical Observations
  40. GRB041223: Swift-BAT detection of a bright long burst
  41. GRB 041218: optical observations
  42. Very high activity of SGR 1806-20
  43. GRB 041219: Second Epoch WSRT Radio Observations
  44. GRB 041219: WSRT Radio Afterglow Detection
  45. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  46. GRB 041218: Optical observations
  47. GRB 041219 : optical follow-up observations
  48. GRB041220: Swift-BAT burst
  49. Deep RAPTOR observations during GRB 041219
  50. GRB 041218 Optical Observations
  51. GRB 041219 Optical Observations
  52. GRB041219c: Third Burst in One Day from Swift-BAT
  53. GRB041219: Optical Afterglow Detection
  54. GRB041219: Continued NIR Observations
  55. GRB041219b: A Swift-BAT burst
  56. GRB 041219 ,optical observation
  57. GRB 041219: Radio Afterglow Detection
  58. GRB 041218 : Radio Observations
  59. GRB 041218: R-band optical observations
  60. GRB041218: Liverpool Telescope optical observations
  61. GRB041218: optical observations
  62. GRB041219: Confirmed NIR Afterglow
  63. GRB041218: Continued P60 Optical Observations
  64. Swift-BAT detection of the bright long burst GRB041219
  65. GRB 041218: Optical Observation
  66. GRB 041219: Infrared Afterglow Candidate
  67. GRB041219, BVRcIc field calibration
  68. GRB 041219: Infrared Afterglow Candidate
  69. GRB041218, BVRcIc field calibration
  70. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  71. GRB041219: P60 Optical Observations
  72. GRB 041219 - A long GRB detected by INTEGRAL
  73. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  74. GRB 041217: PROMPT Observations
  75. GRB041218: optical observations
  76. GRB041217: optical limit 30 min after GRB
  77. GRB 041218; optical candidate
  78. GRB 041218: Optical observations
  79. GRB 041217: LCO40 Optical Observations and Possible Candidates
  80. GRB 041218 - A long GRB detected by integral
  81. GRB041217: Optical Observations
  82. GRB041217: NIR and optical observations with REM
  83. GRB041217: P60 Optical Observations
  84. GRB041217: Infrared Observations
  85. GRB041217: The First GRB Located On-Board Swift
  86. GRB041211: Faulkes Telescope continued optical monitoring
  87. Optical Transient in Lynx not a GRB
  88. Optical transient (GRB?) in Lynx
  89. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  90. GRB041211: Continued P60 Observations
  91. GRB041211: RAPTOR observations
  92. GRB041211: Ashra Prototype optical observation
  93. GRB041211, Faulkes Telescope optical observation
  94. GRB041211, BVRcIc field calibration
  95. GRB041211,optical observation
  96. GRB 041211: Infrared Observations
  97. GRB 041211: KAIT observations
  98. GRB 041211: Optical follow-up in East Asian region
  99. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  100. GRB041211: P60 optical imaging

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