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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. SGR1806-20: Swift-BAT observations of two additional bursts
  2. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  3. Further VLA observations of SGR 1806-20
  4. SGR 1806-20 and extragalactic short-duration GRBs
  5. Further ATCA observations of SGR 1806-20
  6. Fourth Epoch VLA observations of SGR 1806-20
  7. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  8. SGR 1806-20: Temporal and Spectral behavior of radio transient
  9. ATCA observations of SGR 1806-20
  10. SGR 1806-20, RHESSI observations of the 041227 giant flare
  11. Third epoch observations of SGR 1806-20 with VLA
  12. Second Epoch VLA observations of SGR 1806-20
  13. Second-epoch VLA observations of SGR 1806-20
  14. SGR1806: Detection of a Sudden Ionospheric Disturbance
  15. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  16. VLA observations of SGR 1806-20
  17. SGR1806 VLA Observations
  18. VLA observations of SGR 1806-20
  19. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  20. GRB 041217: Optical observations
  21. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  22. GRB041219, early time observations
  23. Detection of the SGR 1806-20 giant outburst back-scattered by the
  24. The giant outburst from SGR 1806-20
  25. IPN localization of giant flare from SGR1806-20
  26. Giant flare from SGR 1806-20 detected by INTEGRAL
  27. GRB041228: ROTSE-III Optical Observations
  28. GRB041228: Swift-BAT detection of a burst
  29. GRB041219; RXTE ASM Observations
  30. NIR Observations of GRB 041219
  31. GRB041226: ROTSE-III Optical Observations
  32. GRB041226: Swift-BAT detection of a burst
  33. GRB041223: decay of the afterglow
  34. GRB041224: ROTSE-III Optical Observations
  35. GRB 041224: near-infrared observations with REM
  36. GRB 041223: XRT afterglow spectrum and light curve
  37. GRB 041223 Fluence measured by Swift-BAT
  38. GRB041224: Swift-BAT detection of a soft burst
  39. GRB041223: optical and NIR observations with REM
  40. Swift-BAT Time History of GRB041219
  41. GRB 041219: TAROT optical observations
  42. GRB 041218: TAROT optical observations
  43. GRB 041223: J-band observations of the afterglow
  44. GRB 041223: Detection of Optical Transient with LCO40
  45. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  46. GRB 041219c: PROMPT Observations
  47. GRB041223: ROTSE-III Optical Observations
  48. GRB041223: Swift-BAT detection of a bright long burst
  49. GRB 041218: optical observations
  50. Very high activity of SGR 1806-20
  51. GRB 041219: Second Epoch WSRT Radio Observations
  52. GRB 041219: WSRT Radio Afterglow Detection
  53. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  54. GRB 041218: Optical observations
  55. GRB 041219 : optical follow-up observations
  56. GRB041220: Swift-BAT burst
  57. Deep RAPTOR observations during GRB 041219
  58. GRB 041218 Optical Observations
  59. GRB 041219 Optical Observations
  60. GRB041219c: Third Burst in One Day from Swift-BAT
  61. GRB041219: Optical Afterglow Detection
  62. GRB041219: Continued NIR Observations
  63. GRB041219b: A Swift-BAT burst
  64. GRB 041219 ,optical observation
  65. GRB 041219: Radio Afterglow Detection
  66. GRB 041218 : Radio Observations
  67. GRB 041218: R-band optical observations
  68. GRB041218: Liverpool Telescope optical observations
  69. GRB041218: optical observations
  70. GRB041219: Confirmed NIR Afterglow
  71. GRB041218: Continued P60 Optical Observations
  72. Swift-BAT detection of the bright long burst GRB041219
  73. GRB 041218: Optical Observation
  74. GRB 041219: Infrared Afterglow Candidate
  75. GRB041219, BVRcIc field calibration
  76. GRB 041219: Infrared Afterglow Candidate
  77. GRB041218, BVRcIc field calibration
  78. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  79. GRB041219: P60 Optical Observations
  80. GRB 041219 - A long GRB detected by INTEGRAL
  81. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  82. GRB 041217: PROMPT Observations
  83. GRB041218: optical observations
  84. GRB041217: optical limit 30 min after GRB
  85. GRB 041218; optical candidate
  86. GRB 041218: Optical observations
  87. GRB 041217: LCO40 Optical Observations and Possible Candidates
  88. GRB 041218 - A long GRB detected by integral
  89. GRB041217: Optical Observations
  90. GRB041217: NIR and optical observations with REM
  91. GRB041217: P60 Optical Observations
  92. GRB041217: Infrared Observations
  93. GRB041217: The First GRB Located On-Board Swift
  94. GRB041211: Faulkes Telescope continued optical monitoring
  95. Optical Transient in Lynx not a GRB
  96. Optical transient (GRB?) in Lynx
  97. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  98. GRB041211: Continued P60 Observations
  99. GRB041211: RAPTOR observations
  100. GRB041211: Ashra Prototype optical observation

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