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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. GRB050124,optical observation
  2. GRB 050124 : Lulin R-band follow-up observation
  3. GRB050124: Updated Swift XRT Position and Fluxes
  4. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  5. GRB050124: Refined BAT position, spectral and fluence information
  6. GRB050124: Swift-BAT position of a double-peaked burst
  7. GRB 050123 : I-band follow-up observation
  8. GRB050123: optical limit 1.8h before GRB
  9. GRB050123,optical observation
  10. GRB 050123: KAIT observations
  11. GRB050123: P60 Observations
  12. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  13. CFHTLS optical transient unlikely to be a GRB
  14. Unusual optical transient (GRB ???)
  15. GRB050117a: Radio Observations
  16. GRB050117a: Refined analysis
  17. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  18. GRB050117: Palomar WIRC Ks-band observations
  19. GRB050117b: Swift-BAT detection of a weak burst
  20. GRB050117: optical observation
  21. GRB 050117, I-band observations
  22. GRB 050117: Optical observation
  23. GRB050117: Refined XRT position
  24. GRB050117: MASTER optical observations
  25. MASTER:GRB050117 SWIFT
  26. GRB050117: Swift-BAT detection of a long multi-peaked burst
  27. GRB050117: Swift XRT Position
  28. SGR 1806-20: RXTE/PCA pulse frequency during flare
  29. Triangulation of Short Hard GRB050112 (large error box)
  30. SGR 1806-20: Further VLA Observations
  31. SGR 1806-20: Further low frequency GMRT results
  32. SGR 1806-20: Further VLA Observations
  33. SGR1806-20: Swift-BAT observations of two additional bursts
  34. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  35. Further VLA observations of SGR 1806-20
  36. SGR 1806-20 and extragalactic short-duration GRBs
  37. Further ATCA observations of SGR 1806-20
  38. Fourth Epoch VLA observations of SGR 1806-20
  39. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  40. SGR 1806-20: Temporal and Spectral behavior of radio transient
  41. ATCA observations of SGR 1806-20
  42. SGR 1806-20, RHESSI observations of the 041227 giant flare
  43. Third epoch observations of SGR 1806-20 with VLA
  44. Second Epoch VLA observations of SGR 1806-20
  45. Second-epoch VLA observations of SGR 1806-20
  46. SGR1806: Detection of a Sudden Ionospheric Disturbance
  47. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  48. VLA observations of SGR 1806-20
  49. SGR1806 VLA Observations
  50. VLA observations of SGR 1806-20
  51. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  52. GRB 041217: Optical observations
  53. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  54. GRB041219, early time observations
  55. Detection of the SGR 1806-20 giant outburst back-scattered by the
  56. The giant outburst from SGR 1806-20
  57. IPN localization of giant flare from SGR1806-20
  58. Giant flare from SGR 1806-20 detected by INTEGRAL
  59. GRB041228: ROTSE-III Optical Observations
  60. GRB041228: Swift-BAT detection of a burst
  61. GRB041219; RXTE ASM Observations
  62. NIR Observations of GRB 041219
  63. GRB041226: ROTSE-III Optical Observations
  64. GRB041226: Swift-BAT detection of a burst
  65. GRB041223: decay of the afterglow
  66. GRB041224: ROTSE-III Optical Observations
  67. GRB 041224: near-infrared observations with REM
  68. GRB 041223: XRT afterglow spectrum and light curve
  69. GRB 041223 Fluence measured by Swift-BAT
  70. GRB041224: Swift-BAT detection of a soft burst
  71. GRB041223: optical and NIR observations with REM
  72. Swift-BAT Time History of GRB041219
  73. GRB 041219: TAROT optical observations
  74. GRB 041218: TAROT optical observations
  75. GRB 041223: J-band observations of the afterglow
  76. GRB 041223: Detection of Optical Transient with LCO40
  77. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  78. GRB 041219c: PROMPT Observations
  79. GRB041223: ROTSE-III Optical Observations
  80. GRB041223: Swift-BAT detection of a bright long burst
  81. GRB 041218: optical observations
  82. Very high activity of SGR 1806-20
  83. GRB 041219: Second Epoch WSRT Radio Observations
  84. GRB 041219: WSRT Radio Afterglow Detection
  85. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  86. GRB 041218: Optical observations
  87. GRB 041219 : optical follow-up observations
  88. GRB041220: Swift-BAT burst
  89. Deep RAPTOR observations during GRB 041219
  90. GRB 041218 Optical Observations
  91. GRB 041219 Optical Observations
  92. GRB041219c: Third Burst in One Day from Swift-BAT
  93. GRB041219: Optical Afterglow Detection
  94. GRB041219: Continued NIR Observations
  95. GRB041219b: A Swift-BAT burst
  96. GRB 041219 ,optical observation
  97. GRB 041219: Radio Afterglow Detection
  98. GRB 041218 : Radio Observations
  99. GRB 041218: R-band optical observations
  100. GRB041218: Liverpool Telescope optical observations

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