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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. GRB 050124: Radio Observations
  2. GRB 050128: near-infrared observations with REM
  3. GRB050128,optical observations
  4. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  5. GRB050126: Updated Swift XRT Position
  6. SGR 1806-20: GMRT results at 240 MHz band.
  7. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  8. GRB 050126: Radio Observations
  9. GRB050128 Swift-BAT observations
  10. GRB 050128: Swift XRT prompt afterglow position
  11. HETE #3667: P60 Observations
  12. GRB 050124: K-band afterglow observations
  13. GRB050126: MASTER optical limit for KECK OT
  14. GRB050126: Burst Parameters Measured by BAT
  15. GRB050126: MASTER optical observations
  16. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  17. GRB 050126: Prompt XRT detection and localization
  18. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  19. GRB050124: No Swift UVOT Detection of Afterglow Emission
  20. GRB 050124, SMARTS optical/IR observations
  21. GRB 050117a: Radio Observations
  22. GRB 050124 I-band observation
  23. GRB 050124: NIR Candidates from Keck/NIRC
  24. GRB050124,optical observation
  25. GRB 050124 : Lulin R-band follow-up observation
  26. GRB050124: Updated Swift XRT Position and Fluxes
  27. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  28. GRB050124: Refined BAT position, spectral and fluence information
  29. GRB050124: Swift-BAT position of a double-peaked burst
  30. GRB 050123 : I-band follow-up observation
  31. GRB050123: optical limit 1.8h before GRB
  32. GRB050123,optical observation
  33. GRB 050123: KAIT observations
  34. GRB050123: P60 Observations
  35. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  36. CFHTLS optical transient unlikely to be a GRB
  37. Unusual optical transient (GRB ???)
  38. GRB050117a: Radio Observations
  39. GRB050117a: Refined analysis
  40. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  41. GRB050117: Palomar WIRC Ks-band observations
  42. GRB050117b: Swift-BAT detection of a weak burst
  43. GRB050117: optical observation
  44. GRB 050117, I-band observations
  45. GRB 050117: Optical observation
  46. GRB050117: Refined XRT position
  47. GRB050117: MASTER optical observations
  48. MASTER:GRB050117 SWIFT
  49. GRB050117: Swift-BAT detection of a long multi-peaked burst
  50. GRB050117: Swift XRT Position
  51. SGR 1806-20: RXTE/PCA pulse frequency during flare
  52. Triangulation of Short Hard GRB050112 (large error box)
  53. SGR 1806-20: Further VLA Observations
  54. SGR 1806-20: Further low frequency GMRT results
  55. SGR 1806-20: Further VLA Observations
  56. SGR1806-20: Swift-BAT observations of two additional bursts
  57. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  58. Further VLA observations of SGR 1806-20
  59. SGR 1806-20 and extragalactic short-duration GRBs
  60. Further ATCA observations of SGR 1806-20
  61. Fourth Epoch VLA observations of SGR 1806-20
  62. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  63. SGR 1806-20: Temporal and Spectral behavior of radio transient
  64. ATCA observations of SGR 1806-20
  65. SGR 1806-20, RHESSI observations of the 041227 giant flare
  66. Third epoch observations of SGR 1806-20 with VLA
  67. Second Epoch VLA observations of SGR 1806-20
  68. Second-epoch VLA observations of SGR 1806-20
  69. SGR1806: Detection of a Sudden Ionospheric Disturbance
  70. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  71. VLA observations of SGR 1806-20
  72. SGR1806 VLA Observations
  73. VLA observations of SGR 1806-20
  74. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  75. GRB 041217: Optical observations
  76. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  77. GRB041219, early time observations
  78. Detection of the SGR 1806-20 giant outburst back-scattered by the
  79. The giant outburst from SGR 1806-20
  80. IPN localization of giant flare from SGR1806-20
  81. Giant flare from SGR 1806-20 detected by INTEGRAL
  82. GRB041228: ROTSE-III Optical Observations
  83. GRB041228: Swift-BAT detection of a burst
  84. GRB041219; RXTE ASM Observations
  85. NIR Observations of GRB 041219
  86. GRB041226: ROTSE-III Optical Observations
  87. GRB041226: Swift-BAT detection of a burst
  88. GRB041223: decay of the afterglow
  89. GRB041224: ROTSE-III Optical Observations
  90. GRB 041224: near-infrared observations with REM
  91. GRB 041223: XRT afterglow spectrum and light curve
  92. GRB 041223 Fluence measured by Swift-BAT
  93. GRB041224: Swift-BAT detection of a soft burst
  94. GRB041223: optical and NIR observations with REM
  95. Swift-BAT Time History of GRB041219
  96. GRB 041219: TAROT optical observations
  97. GRB 041218: TAROT optical observations
  98. GRB 041223: J-band observations of the afterglow
  99. GRB 041223: Detection of Optical Transient with LCO40
  100. GRB041223: Swift XRT Detection of X-ray Afterglow Emission

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