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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. Further analysis of the short Swift-BAT GRB 050202
  2. GRB 050202: Second epoch radio observations
  3. GRB 050129: Optical observations
  4. GRB050202: Radio Observations
  5. GRB 050202: Optical observations with LCO40
  6. GRB 050202: Short burst detected by Swift-BAT
  7. GRB 050128 Optical observation with REM
  8. GRB 050129: a weak long GRB detected with INTEGRAL
  9. SGR1806-20: Swift-BAT detection of a large normal burst
  10. GRB050128: Faulkes Telescope South observations
  11. GRB 050124: Radio Observations
  12. GRB 050128: near-infrared observations with REM
  13. GRB050128,optical observations
  14. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  15. GRB050126: Updated Swift XRT Position
  16. SGR 1806-20: GMRT results at 240 MHz band.
  17. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  18. GRB 050126: Radio Observations
  19. GRB050128 Swift-BAT observations
  20. GRB 050128: Swift XRT prompt afterglow position
  21. HETE #3667: P60 Observations
  22. GRB 050124: K-band afterglow observations
  23. GRB050126: MASTER optical limit for KECK OT
  24. GRB050126: Burst Parameters Measured by BAT
  25. GRB050126: MASTER optical observations
  26. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  27. GRB 050126: Prompt XRT detection and localization
  28. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  29. GRB050124: No Swift UVOT Detection of Afterglow Emission
  30. GRB 050124, SMARTS optical/IR observations
  31. GRB 050117a: Radio Observations
  32. GRB 050124 I-band observation
  33. GRB 050124: NIR Candidates from Keck/NIRC
  34. GRB050124,optical observation
  35. GRB 050124 : Lulin R-band follow-up observation
  36. GRB050124: Updated Swift XRT Position and Fluxes
  37. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  38. GRB050124: Refined BAT position, spectral and fluence information
  39. GRB050124: Swift-BAT position of a double-peaked burst
  40. GRB 050123 : I-band follow-up observation
  41. GRB050123: optical limit 1.8h before GRB
  42. GRB050123,optical observation
  43. GRB 050123: KAIT observations
  44. GRB050123: P60 Observations
  45. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  46. CFHTLS optical transient unlikely to be a GRB
  47. Unusual optical transient (GRB ???)
  48. GRB050117a: Radio Observations
  49. GRB050117a: Refined analysis
  50. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  51. GRB050117: Palomar WIRC Ks-band observations
  52. GRB050117b: Swift-BAT detection of a weak burst
  53. GRB050117: optical observation
  54. GRB 050117, I-band observations
  55. GRB 050117: Optical observation
  56. GRB050117: Refined XRT position
  57. GRB050117: MASTER optical observations
  58. MASTER:GRB050117 SWIFT
  59. GRB050117: Swift-BAT detection of a long multi-peaked burst
  60. GRB050117: Swift XRT Position
  61. SGR 1806-20: RXTE/PCA pulse frequency during flare
  62. Triangulation of Short Hard GRB050112 (large error box)
  63. SGR 1806-20: Further VLA Observations
  64. SGR 1806-20: Further low frequency GMRT results
  65. SGR 1806-20: Further VLA Observations
  66. SGR1806-20: Swift-BAT observations of two additional bursts
  67. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  68. Further VLA observations of SGR 1806-20
  69. SGR 1806-20 and extragalactic short-duration GRBs
  70. Further ATCA observations of SGR 1806-20
  71. Fourth Epoch VLA observations of SGR 1806-20
  72. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  73. SGR 1806-20: Temporal and Spectral behavior of radio transient
  74. ATCA observations of SGR 1806-20
  75. SGR 1806-20, RHESSI observations of the 041227 giant flare
  76. Third epoch observations of SGR 1806-20 with VLA
  77. Second Epoch VLA observations of SGR 1806-20
  78. Second-epoch VLA observations of SGR 1806-20
  79. SGR1806: Detection of a Sudden Ionospheric Disturbance
  80. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  81. VLA observations of SGR 1806-20
  82. SGR1806 VLA Observations
  83. VLA observations of SGR 1806-20
  84. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  85. GRB 041217: Optical observations
  86. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  87. GRB041219, early time observations
  88. Detection of the SGR 1806-20 giant outburst back-scattered by the
  89. The giant outburst from SGR 1806-20
  90. IPN localization of giant flare from SGR1806-20
  91. Giant flare from SGR 1806-20 detected by INTEGRAL
  92. GRB041228: ROTSE-III Optical Observations
  93. GRB041228: Swift-BAT detection of a burst
  94. GRB041219; RXTE ASM Observations
  95. NIR Observations of GRB 041219
  96. GRB041226: ROTSE-III Optical Observations
  97. GRB041226: Swift-BAT detection of a burst
  98. GRB041223: decay of the afterglow
  99. GRB041224: ROTSE-III Optical Observations
  100. GRB 041224: near-infrared observations with REM

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