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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: NIR afterglow confirmed with Keck/NIRC
  2. GRB050124: No Swift UVOT Detection of Afterglow Emission
  3. GRB 050124, SMARTS optical/IR observations
  4. GRB 050117a: Radio Observations
  5. GRB 050124 I-band observation
  6. GRB 050124: NIR Candidates from Keck/NIRC
  7. GRB050124,optical observation
  8. GRB 050124 : Lulin R-band follow-up observation
  9. GRB050124: Updated Swift XRT Position and Fluxes
  10. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  11. GRB050124: Refined BAT position, spectral and fluence information
  12. GRB050124: Swift-BAT position of a double-peaked burst
  13. GRB 050123 : I-band follow-up observation
  14. GRB050123: optical limit 1.8h before GRB
  15. GRB050123,optical observation
  16. GRB 050123: KAIT observations
  17. GRB050123: P60 Observations
  18. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  19. CFHTLS optical transient unlikely to be a GRB
  20. Unusual optical transient (GRB ???)
  21. GRB050117a: Radio Observations
  22. GRB050117a: Refined analysis
  23. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  24. GRB050117: Palomar WIRC Ks-band observations
  25. GRB050117b: Swift-BAT detection of a weak burst
  26. GRB050117: optical observation
  27. GRB 050117, I-band observations
  28. GRB 050117: Optical observation
  29. GRB050117: Refined XRT position
  30. GRB050117: MASTER optical observations
  31. MASTER:GRB050117 SWIFT
  32. GRB050117: Swift-BAT detection of a long multi-peaked burst
  33. GRB050117: Swift XRT Position
  34. SGR 1806-20: RXTE/PCA pulse frequency during flare
  35. Triangulation of Short Hard GRB050112 (large error box)
  36. SGR 1806-20: Further VLA Observations
  37. SGR 1806-20: Further low frequency GMRT results
  38. SGR 1806-20: Further VLA Observations
  39. SGR1806-20: Swift-BAT observations of two additional bursts
  40. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  41. Further VLA observations of SGR 1806-20
  42. SGR 1806-20 and extragalactic short-duration GRBs
  43. Further ATCA observations of SGR 1806-20
  44. Fourth Epoch VLA observations of SGR 1806-20
  45. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  46. SGR 1806-20: Temporal and Spectral behavior of radio transient
  47. ATCA observations of SGR 1806-20
  48. SGR 1806-20, RHESSI observations of the 041227 giant flare
  49. Third epoch observations of SGR 1806-20 with VLA
  50. Second Epoch VLA observations of SGR 1806-20
  51. Second-epoch VLA observations of SGR 1806-20
  52. SGR1806: Detection of a Sudden Ionospheric Disturbance
  53. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  54. VLA observations of SGR 1806-20
  55. SGR1806 VLA Observations
  56. VLA observations of SGR 1806-20
  57. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  58. GRB 041217: Optical observations
  59. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  60. GRB041219, early time observations
  61. Detection of the SGR 1806-20 giant outburst back-scattered by the
  62. The giant outburst from SGR 1806-20
  63. IPN localization of giant flare from SGR1806-20
  64. Giant flare from SGR 1806-20 detected by INTEGRAL
  65. GRB041228: ROTSE-III Optical Observations
  66. GRB041228: Swift-BAT detection of a burst
  67. GRB041219; RXTE ASM Observations
  68. NIR Observations of GRB 041219
  69. GRB041226: ROTSE-III Optical Observations
  70. GRB041226: Swift-BAT detection of a burst
  71. GRB041223: decay of the afterglow
  72. GRB041224: ROTSE-III Optical Observations
  73. GRB 041224: near-infrared observations with REM
  74. GRB 041223: XRT afterglow spectrum and light curve
  75. GRB 041223 Fluence measured by Swift-BAT
  76. GRB041224: Swift-BAT detection of a soft burst
  77. GRB041223: optical and NIR observations with REM
  78. Swift-BAT Time History of GRB041219
  79. GRB 041219: TAROT optical observations
  80. GRB 041218: TAROT optical observations
  81. GRB 041223: J-band observations of the afterglow
  82. GRB 041223: Detection of Optical Transient with LCO40
  83. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  84. GRB 041219c: PROMPT Observations
  85. GRB041223: ROTSE-III Optical Observations
  86. GRB041223: Swift-BAT detection of a bright long burst
  87. GRB 041218: optical observations
  88. Very high activity of SGR 1806-20
  89. GRB 041219: Second Epoch WSRT Radio Observations
  90. GRB 041219: WSRT Radio Afterglow Detection
  91. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  92. GRB 041218: Optical observations
  93. GRB 041219 : optical follow-up observations
  94. GRB041220: Swift-BAT burst
  95. Deep RAPTOR observations during GRB 041219
  96. GRB 041218 Optical Observations
  97. GRB 041219 Optical Observations
  98. GRB041219c: Third Burst in One Day from Swift-BAT
  99. GRB041219: Optical Afterglow Detection
  100. GRB041219: Continued NIR Observations

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