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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. GRB050126: Burst Parameters Measured by BAT
  2. GRB050126: MASTER optical observations
  3. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  4. GRB 050126: Prompt XRT detection and localization
  5. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  6. GRB050124: No Swift UVOT Detection of Afterglow Emission
  7. GRB 050124, SMARTS optical/IR observations
  8. GRB 050117a: Radio Observations
  9. GRB 050124 I-band observation
  10. GRB 050124: NIR Candidates from Keck/NIRC
  11. GRB050124,optical observation
  12. GRB 050124 : Lulin R-band follow-up observation
  13. GRB050124: Updated Swift XRT Position and Fluxes
  14. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  15. GRB050124: Refined BAT position, spectral and fluence information
  16. GRB050124: Swift-BAT position of a double-peaked burst
  17. GRB 050123 : I-band follow-up observation
  18. GRB050123: optical limit 1.8h before GRB
  19. GRB050123,optical observation
  20. GRB 050123: KAIT observations
  21. GRB050123: P60 Observations
  22. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  23. CFHTLS optical transient unlikely to be a GRB
  24. Unusual optical transient (GRB ???)
  25. GRB050117a: Radio Observations
  26. GRB050117a: Refined analysis
  27. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  28. GRB050117: Palomar WIRC Ks-band observations
  29. GRB050117b: Swift-BAT detection of a weak burst
  30. GRB050117: optical observation
  31. GRB 050117, I-band observations
  32. GRB 050117: Optical observation
  33. GRB050117: Refined XRT position
  34. GRB050117: MASTER optical observations
  35. MASTER:GRB050117 SWIFT
  36. GRB050117: Swift-BAT detection of a long multi-peaked burst
  37. GRB050117: Swift XRT Position
  38. SGR 1806-20: RXTE/PCA pulse frequency during flare
  39. Triangulation of Short Hard GRB050112 (large error box)
  40. SGR 1806-20: Further VLA Observations
  41. SGR 1806-20: Further low frequency GMRT results
  42. SGR 1806-20: Further VLA Observations
  43. SGR1806-20: Swift-BAT observations of two additional bursts
  44. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  45. Further VLA observations of SGR 1806-20
  46. SGR 1806-20 and extragalactic short-duration GRBs
  47. Further ATCA observations of SGR 1806-20
  48. Fourth Epoch VLA observations of SGR 1806-20
  49. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  50. SGR 1806-20: Temporal and Spectral behavior of radio transient
  51. ATCA observations of SGR 1806-20
  52. SGR 1806-20, RHESSI observations of the 041227 giant flare
  53. Third epoch observations of SGR 1806-20 with VLA
  54. Second Epoch VLA observations of SGR 1806-20
  55. Second-epoch VLA observations of SGR 1806-20
  56. SGR1806: Detection of a Sudden Ionospheric Disturbance
  57. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  58. VLA observations of SGR 1806-20
  59. SGR1806 VLA Observations
  60. VLA observations of SGR 1806-20
  61. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  62. GRB 041217: Optical observations
  63. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  64. GRB041219, early time observations
  65. Detection of the SGR 1806-20 giant outburst back-scattered by the
  66. The giant outburst from SGR 1806-20
  67. IPN localization of giant flare from SGR1806-20
  68. Giant flare from SGR 1806-20 detected by INTEGRAL
  69. GRB041228: ROTSE-III Optical Observations
  70. GRB041228: Swift-BAT detection of a burst
  71. GRB041219; RXTE ASM Observations
  72. NIR Observations of GRB 041219
  73. GRB041226: ROTSE-III Optical Observations
  74. GRB041226: Swift-BAT detection of a burst
  75. GRB041223: decay of the afterglow
  76. GRB041224: ROTSE-III Optical Observations
  77. GRB 041224: near-infrared observations with REM
  78. GRB 041223: XRT afterglow spectrum and light curve
  79. GRB 041223 Fluence measured by Swift-BAT
  80. GRB041224: Swift-BAT detection of a soft burst
  81. GRB041223: optical and NIR observations with REM
  82. Swift-BAT Time History of GRB041219
  83. GRB 041219: TAROT optical observations
  84. GRB 041218: TAROT optical observations
  85. GRB 041223: J-band observations of the afterglow
  86. GRB 041223: Detection of Optical Transient with LCO40
  87. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  88. GRB 041219c: PROMPT Observations
  89. GRB041223: ROTSE-III Optical Observations
  90. GRB041223: Swift-BAT detection of a bright long burst
  91. GRB 041218: optical observations
  92. Very high activity of SGR 1806-20
  93. GRB 041219: Second Epoch WSRT Radio Observations
  94. GRB 041219: WSRT Radio Afterglow Detection
  95. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  96. GRB 041218: Optical observations
  97. GRB 041219 : optical follow-up observations
  98. GRB041220: Swift-BAT burst
  99. Deep RAPTOR observations during GRB 041219
  100. GRB 041218 Optical Observations

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