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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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB050215B: ROTSE-III optical observations
  2. GRB050215A: ROTSE-III Optical Observations
  3. GRB050209: TAROT optical observations
  4. GRB 050209(=U11568): Duration and spectrum
  5. short/hard GRB 050202, optical observations
  6. GRB050209: REM optical observations
  7. GRB 050209 I-band observation
  8. GRB 050209 Optical observations
  9. GRB050209: P60 Optical Observations
  10. GRB050209 (=U11568): A Long GRB Detected by HETE
  11. GRB 050209: Optical observation
  12. GRB 050128: Radio observations
  13. Further analysis of the short Swift-BAT GRB 050202
  14. GRB 050202: Second epoch radio observations
  15. GRB 050129: Optical observations
  16. GRB050202: Radio Observations
  17. GRB 050202: Optical observations with LCO40
  18. GRB 050202: Short burst detected by Swift-BAT
  19. GRB 050128 Optical observation with REM
  20. GRB 050129: a weak long GRB detected with INTEGRAL
  21. SGR1806-20: Swift-BAT detection of a large normal burst
  22. GRB050128: Faulkes Telescope South observations
  23. GRB 050124: Radio Observations
  24. GRB 050128: near-infrared observations with REM
  25. GRB050128,optical observations
  26. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  27. GRB050126: Updated Swift XRT Position
  28. SGR 1806-20: GMRT results at 240 MHz band.
  29. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  30. GRB 050126: Radio Observations
  31. GRB050128 Swift-BAT observations
  32. GRB 050128: Swift XRT prompt afterglow position
  33. HETE #3667: P60 Observations
  34. GRB 050124: K-band afterglow observations
  35. GRB050126: MASTER optical limit for KECK OT
  36. GRB050126: Burst Parameters Measured by BAT
  37. GRB050126: MASTER optical observations
  38. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  39. GRB 050126: Prompt XRT detection and localization
  40. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  41. GRB050124: No Swift UVOT Detection of Afterglow Emission
  42. GRB 050124, SMARTS optical/IR observations
  43. GRB 050117a: Radio Observations
  44. GRB 050124 I-band observation
  45. GRB 050124: NIR Candidates from Keck/NIRC
  46. GRB050124,optical observation
  47. GRB 050124 : Lulin R-band follow-up observation
  48. GRB050124: Updated Swift XRT Position and Fluxes
  49. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  50. GRB050124: Refined BAT position, spectral and fluence information
  51. GRB050124: Swift-BAT position of a double-peaked burst
  52. GRB 050123 : I-band follow-up observation
  53. GRB050123: optical limit 1.8h before GRB
  54. GRB050123,optical observation
  55. GRB 050123: KAIT observations
  56. GRB050123: P60 Observations
  57. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  58. CFHTLS optical transient unlikely to be a GRB
  59. Unusual optical transient (GRB ???)
  60. GRB050117a: Radio Observations
  61. GRB050117a: Refined analysis
  62. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  63. GRB050117: Palomar WIRC Ks-band observations
  64. GRB050117b: Swift-BAT detection of a weak burst
  65. GRB050117: optical observation
  66. GRB 050117, I-band observations
  67. GRB 050117: Optical observation
  68. GRB050117: Refined XRT position
  69. GRB050117: MASTER optical observations
  70. MASTER:GRB050117 SWIFT
  71. GRB050117: Swift-BAT detection of a long multi-peaked burst
  72. GRB050117: Swift XRT Position
  73. SGR 1806-20: RXTE/PCA pulse frequency during flare
  74. Triangulation of Short Hard GRB050112 (large error box)
  75. SGR 1806-20: Further VLA Observations
  76. SGR 1806-20: Further low frequency GMRT results
  77. SGR 1806-20: Further VLA Observations
  78. SGR1806-20: Swift-BAT observations of two additional bursts
  79. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  80. Further VLA observations of SGR 1806-20
  81. SGR 1806-20 and extragalactic short-duration GRBs
  82. Further ATCA observations of SGR 1806-20
  83. Fourth Epoch VLA observations of SGR 1806-20
  84. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  85. SGR 1806-20: Temporal and Spectral behavior of radio transient
  86. ATCA observations of SGR 1806-20
  87. SGR 1806-20, RHESSI observations of the 041227 giant flare
  88. Third epoch observations of SGR 1806-20 with VLA
  89. Second Epoch VLA observations of SGR 1806-20
  90. Second-epoch VLA observations of SGR 1806-20
  91. SGR1806: Detection of a Sudden Ionospheric Disturbance
  92. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  93. VLA observations of SGR 1806-20
  94. SGR1806 VLA Observations
  95. VLA observations of SGR 1806-20
  96. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  97. GRB 041217: Optical observations
  98. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  99. GRB041219, early time observations
  100. Detection of the SGR 1806-20 giant outburst back-scattered by the

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