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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 050219a: Refined XRT position
  2. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  3. GRB 050219: Swift-BAT detection of a burst
  4. GRB050215b: Swift UVOT Detection of Afterglow Emission
  5. GRB 050219: Prompt X-ray position
  6. GRB 050215B: Radio Observations
  7. GRB 050215b: XRT confirmation of IR afterglow candidate
  8. GRB050215b: P60 Optical Observations
  9. GRB 050215b: Swift XRT Source Variability
  10. GRB 050215B: candidate afterglow
  11. GRB 050215b : Lulin follow-up observation
  12. GRB 050215b, BOOTES-2 simultaneous optical observations
  13. GRB 050215B: UKIRT K-band imaging
  14. GRB 050215b: Swift XRT Observations
  15. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  16. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  17. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  18. GRB 050215b, BOOTES-1B optical limit
  19. GRB050215B: ROTSE-III optical observations
  20. GRB050215A: ROTSE-III Optical Observations
  21. GRB050209: TAROT optical observations
  22. GRB 050209(=U11568): Duration and spectrum
  23. short/hard GRB 050202, optical observations
  24. GRB050209: REM optical observations
  25. GRB 050209 I-band observation
  26. GRB 050209 Optical observations
  27. GRB050209: P60 Optical Observations
  28. GRB050209 (=U11568): A Long GRB Detected by HETE
  29. GRB 050209: Optical observation
  30. GRB 050128: Radio observations
  31. Further analysis of the short Swift-BAT GRB 050202
  32. GRB 050202: Second epoch radio observations
  33. GRB 050129: Optical observations
  34. GRB050202: Radio Observations
  35. GRB 050202: Optical observations with LCO40
  36. GRB 050202: Short burst detected by Swift-BAT
  37. GRB 050128 Optical observation with REM
  38. GRB 050129: a weak long GRB detected with INTEGRAL
  39. SGR1806-20: Swift-BAT detection of a large normal burst
  40. GRB050128: Faulkes Telescope South observations
  41. GRB 050124: Radio Observations
  42. GRB 050128: near-infrared observations with REM
  43. GRB050128,optical observations
  44. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  45. GRB050126: Updated Swift XRT Position
  46. SGR 1806-20: GMRT results at 240 MHz band.
  47. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  48. GRB 050126: Radio Observations
  49. GRB050128 Swift-BAT observations
  50. GRB 050128: Swift XRT prompt afterglow position
  51. HETE #3667: P60 Observations
  52. GRB 050124: K-band afterglow observations
  53. GRB050126: MASTER optical limit for KECK OT
  54. GRB050126: Burst Parameters Measured by BAT
  55. GRB050126: MASTER optical observations
  56. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  57. GRB 050126: Prompt XRT detection and localization
  58. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  59. GRB050124: No Swift UVOT Detection of Afterglow Emission
  60. GRB 050124, SMARTS optical/IR observations
  61. GRB 050117a: Radio Observations
  62. GRB 050124 I-band observation
  63. GRB 050124: NIR Candidates from Keck/NIRC
  64. GRB050124,optical observation
  65. GRB 050124 : Lulin R-band follow-up observation
  66. GRB050124: Updated Swift XRT Position and Fluxes
  67. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  68. GRB050124: Refined BAT position, spectral and fluence information
  69. GRB050124: Swift-BAT position of a double-peaked burst
  70. GRB 050123 : I-band follow-up observation
  71. GRB050123: optical limit 1.8h before GRB
  72. GRB050123,optical observation
  73. GRB 050123: KAIT observations
  74. GRB050123: P60 Observations
  75. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  76. CFHTLS optical transient unlikely to be a GRB
  77. Unusual optical transient (GRB ???)
  78. GRB050117a: Radio Observations
  79. GRB050117a: Refined analysis
  80. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  81. GRB050117: Palomar WIRC Ks-band observations
  82. GRB050117b: Swift-BAT detection of a weak burst
  83. GRB050117: optical observation
  84. GRB 050117, I-band observations
  85. GRB 050117: Optical observation
  86. GRB050117: Refined XRT position
  87. GRB050117: MASTER optical observations
  88. MASTER:GRB050117 SWIFT
  89. GRB050117: Swift-BAT detection of a long multi-peaked burst
  90. GRB050117: Swift XRT Position
  91. SGR 1806-20: RXTE/PCA pulse frequency during flare
  92. Triangulation of Short Hard GRB050112 (large error box)
  93. SGR 1806-20: Further VLA Observations
  94. SGR 1806-20: Further low frequency GMRT results
  95. SGR 1806-20: Further VLA Observations
  96. SGR1806-20: Swift-BAT observations of two additional bursts
  97. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  98. Further VLA observations of SGR 1806-20
  99. SGR 1806-20 and extragalactic short-duration GRBs
  100. Further ATCA observations of SGR 1806-20

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