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

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