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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. GRB050117: optical observation
  2. GRB 050117, I-band observations
  3. GRB 050117: Optical observation
  4. GRB050117: Refined XRT position
  5. GRB050117: MASTER optical observations
  6. MASTER:GRB050117 SWIFT
  7. GRB050117: Swift-BAT detection of a long multi-peaked burst
  8. GRB050117: Swift XRT Position
  9. SGR 1806-20: RXTE/PCA pulse frequency during flare
  10. Triangulation of Short Hard GRB050112 (large error box)
  11. SGR 1806-20: Further VLA Observations
  12. SGR 1806-20: Further low frequency GMRT results
  13. SGR 1806-20: Further VLA Observations
  14. SGR1806-20: Swift-BAT observations of two additional bursts
  15. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  16. Further VLA observations of SGR 1806-20
  17. SGR 1806-20 and extragalactic short-duration GRBs
  18. Further ATCA observations of SGR 1806-20
  19. Fourth Epoch VLA observations of SGR 1806-20
  20. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  21. SGR 1806-20: Temporal and Spectral behavior of radio transient
  22. ATCA observations of SGR 1806-20
  23. SGR 1806-20, RHESSI observations of the 041227 giant flare
  24. Third epoch observations of SGR 1806-20 with VLA
  25. Second Epoch VLA observations of SGR 1806-20
  26. Second-epoch VLA observations of SGR 1806-20
  27. SGR1806: Detection of a Sudden Ionospheric Disturbance
  28. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  29. VLA observations of SGR 1806-20
  30. SGR1806 VLA Observations
  31. VLA observations of SGR 1806-20
  32. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  33. GRB 041217: Optical observations
  34. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  35. GRB041219, early time observations
  36. Detection of the SGR 1806-20 giant outburst back-scattered by the
  37. The giant outburst from SGR 1806-20
  38. IPN localization of giant flare from SGR1806-20
  39. Giant flare from SGR 1806-20 detected by INTEGRAL
  40. GRB041228: ROTSE-III Optical Observations
  41. GRB041228: Swift-BAT detection of a burst
  42. GRB041219; RXTE ASM Observations
  43. NIR Observations of GRB 041219
  44. GRB041226: ROTSE-III Optical Observations
  45. GRB041226: Swift-BAT detection of a burst
  46. GRB041223: decay of the afterglow
  47. GRB041224: ROTSE-III Optical Observations
  48. GRB 041224: near-infrared observations with REM
  49. GRB 041223: XRT afterglow spectrum and light curve
  50. GRB 041223 Fluence measured by Swift-BAT
  51. GRB041224: Swift-BAT detection of a soft burst
  52. GRB041223: optical and NIR observations with REM
  53. Swift-BAT Time History of GRB041219
  54. GRB 041219: TAROT optical observations
  55. GRB 041218: TAROT optical observations
  56. GRB 041223: J-band observations of the afterglow
  57. GRB 041223: Detection of Optical Transient with LCO40
  58. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  59. GRB 041219c: PROMPT Observations
  60. GRB041223: ROTSE-III Optical Observations
  61. GRB041223: Swift-BAT detection of a bright long burst
  62. GRB 041218: optical observations
  63. Very high activity of SGR 1806-20
  64. GRB 041219: Second Epoch WSRT Radio Observations
  65. GRB 041219: WSRT Radio Afterglow Detection
  66. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  67. GRB 041218: Optical observations
  68. GRB 041219 : optical follow-up observations
  69. GRB041220: Swift-BAT burst
  70. Deep RAPTOR observations during GRB 041219
  71. GRB 041218 Optical Observations
  72. GRB 041219 Optical Observations
  73. GRB041219c: Third Burst in One Day from Swift-BAT
  74. GRB041219: Optical Afterglow Detection
  75. GRB041219: Continued NIR Observations
  76. GRB041219b: A Swift-BAT burst
  77. GRB 041219 ,optical observation
  78. GRB 041219: Radio Afterglow Detection
  79. GRB 041218 : Radio Observations
  80. GRB 041218: R-band optical observations
  81. GRB041218: Liverpool Telescope optical observations
  82. GRB041218: optical observations
  83. GRB041219: Confirmed NIR Afterglow
  84. GRB041218: Continued P60 Optical Observations
  85. Swift-BAT detection of the bright long burst GRB041219
  86. GRB 041218: Optical Observation
  87. GRB 041219: Infrared Afterglow Candidate
  88. GRB041219, BVRcIc field calibration
  89. GRB 041219: Infrared Afterglow Candidate
  90. GRB041218, BVRcIc field calibration
  91. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  92. GRB041219: P60 Optical Observations
  93. GRB 041219 - A long GRB detected by INTEGRAL
  94. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  95. GRB 041217: PROMPT Observations
  96. GRB041218: optical observations
  97. GRB041217: optical limit 30 min after GRB
  98. GRB 041218; optical candidate
  99. GRB 041218: Optical observations
  100. GRB 041217: LCO40 Optical Observations and Possible Candidates

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