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

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