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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. GRB050215b: Swift UVOT Detection of Afterglow Emission
  2. GRB 050219: Prompt X-ray position
  3. GRB 050215B: Radio Observations
  4. GRB 050215b: XRT confirmation of IR afterglow candidate
  5. GRB050215b: P60 Optical Observations
  6. GRB 050215b: Swift XRT Source Variability
  7. GRB 050215B: candidate afterglow
  8. GRB 050215b : Lulin follow-up observation
  9. GRB 050215b, BOOTES-2 simultaneous optical observations
  10. GRB 050215B: UKIRT K-band imaging
  11. GRB 050215b: Swift XRT Observations
  12. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  13. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  14. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  15. GRB 050215b, BOOTES-1B optical limit
  16. GRB050215B: ROTSE-III optical observations
  17. GRB050215A: ROTSE-III Optical Observations
  18. GRB050209: TAROT optical observations
  19. GRB 050209(=U11568): Duration and spectrum
  20. short/hard GRB 050202, optical observations
  21. GRB050209: REM optical observations
  22. GRB 050209 I-band observation
  23. GRB 050209 Optical observations
  24. GRB050209: P60 Optical Observations
  25. GRB050209 (=U11568): A Long GRB Detected by HETE
  26. GRB 050209: Optical observation
  27. GRB 050128: Radio observations
  28. Further analysis of the short Swift-BAT GRB 050202
  29. GRB 050202: Second epoch radio observations
  30. GRB 050129: Optical observations
  31. GRB050202: Radio Observations
  32. GRB 050202: Optical observations with LCO40
  33. GRB 050202: Short burst detected by Swift-BAT
  34. GRB 050128 Optical observation with REM
  35. GRB 050129: a weak long GRB detected with INTEGRAL
  36. SGR1806-20: Swift-BAT detection of a large normal burst
  37. GRB050128: Faulkes Telescope South observations
  38. GRB 050124: Radio Observations
  39. GRB 050128: near-infrared observations with REM
  40. GRB050128,optical observations
  41. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  42. GRB050126: Updated Swift XRT Position
  43. SGR 1806-20: GMRT results at 240 MHz band.
  44. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  45. GRB 050126: Radio Observations
  46. GRB050128 Swift-BAT observations
  47. GRB 050128: Swift XRT prompt afterglow position
  48. HETE #3667: P60 Observations
  49. GRB 050124: K-band afterglow observations
  50. GRB050126: MASTER optical limit for KECK OT
  51. GRB050126: Burst Parameters Measured by BAT
  52. GRB050126: MASTER optical observations
  53. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  54. GRB 050126: Prompt XRT detection and localization
  55. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  56. GRB050124: No Swift UVOT Detection of Afterglow Emission
  57. GRB 050124, SMARTS optical/IR observations
  58. GRB 050117a: Radio Observations
  59. GRB 050124 I-band observation
  60. GRB 050124: NIR Candidates from Keck/NIRC
  61. GRB050124,optical observation
  62. GRB 050124 : Lulin R-band follow-up observation
  63. GRB050124: Updated Swift XRT Position and Fluxes
  64. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  65. GRB050124: Refined BAT position, spectral and fluence information
  66. GRB050124: Swift-BAT position of a double-peaked burst
  67. GRB 050123 : I-band follow-up observation
  68. GRB050123: optical limit 1.8h before GRB
  69. GRB050123,optical observation
  70. GRB 050123: KAIT observations
  71. GRB050123: P60 Observations
  72. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  73. CFHTLS optical transient unlikely to be a GRB
  74. Unusual optical transient (GRB ???)
  75. GRB050117a: Radio Observations
  76. GRB050117a: Refined analysis
  77. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  78. GRB050117: Palomar WIRC Ks-band observations
  79. GRB050117b: Swift-BAT detection of a weak burst
  80. GRB050117: optical observation
  81. GRB 050117, I-band observations
  82. GRB 050117: Optical observation
  83. GRB050117: Refined XRT position
  84. GRB050117: MASTER optical observations
  85. MASTER:GRB050117 SWIFT
  86. GRB050117: Swift-BAT detection of a long multi-peaked burst
  87. GRB050117: Swift XRT Position
  88. SGR 1806-20: RXTE/PCA pulse frequency during flare
  89. Triangulation of Short Hard GRB050112 (large error box)
  90. SGR 1806-20: Further VLA Observations
  91. SGR 1806-20: Further low frequency GMRT results
  92. SGR 1806-20: Further VLA Observations
  93. SGR1806-20: Swift-BAT observations of two additional bursts
  94. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  95. Further VLA observations of SGR 1806-20
  96. SGR 1806-20 and extragalactic short-duration GRBs
  97. Further ATCA observations of SGR 1806-20
  98. Fourth Epoch VLA observations of SGR 1806-20
  99. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  100. SGR 1806-20: Temporal and Spectral behavior of radio transient

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