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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. IPN localization of giant flare from SGR1806-20
  2. Giant flare from SGR 1806-20 detected by INTEGRAL
  3. GRB041228: ROTSE-III Optical Observations
  4. GRB041228: Swift-BAT detection of a burst
  5. GRB041219; RXTE ASM Observations
  6. NIR Observations of GRB 041219
  7. GRB041226: ROTSE-III Optical Observations
  8. GRB041226: Swift-BAT detection of a burst
  9. GRB041223: decay of the afterglow
  10. GRB041224: ROTSE-III Optical Observations
  11. GRB 041224: near-infrared observations with REM
  12. GRB 041223: XRT afterglow spectrum and light curve
  13. GRB 041223 Fluence measured by Swift-BAT
  14. GRB041224: Swift-BAT detection of a soft burst
  15. GRB041223: optical and NIR observations with REM
  16. Swift-BAT Time History of GRB041219
  17. GRB 041219: TAROT optical observations
  18. GRB 041218: TAROT optical observations
  19. GRB 041223: J-band observations of the afterglow
  20. GRB 041223: Detection of Optical Transient with LCO40
  21. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  22. GRB 041219c: PROMPT Observations
  23. GRB041223: ROTSE-III Optical Observations
  24. GRB041223: Swift-BAT detection of a bright long burst
  25. GRB 041218: optical observations
  26. Very high activity of SGR 1806-20
  27. GRB 041219: Second Epoch WSRT Radio Observations
  28. GRB 041219: WSRT Radio Afterglow Detection
  29. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  30. GRB 041218: Optical observations
  31. GRB 041219 : optical follow-up observations
  32. GRB041220: Swift-BAT burst
  33. Deep RAPTOR observations during GRB 041219
  34. GRB 041218 Optical Observations
  35. GRB 041219 Optical Observations
  36. GRB041219c: Third Burst in One Day from Swift-BAT
  37. GRB041219: Optical Afterglow Detection
  38. GRB041219: Continued NIR Observations
  39. GRB041219b: A Swift-BAT burst
  40. GRB 041219 ,optical observation
  41. GRB 041219: Radio Afterglow Detection
  42. GRB 041218 : Radio Observations
  43. GRB 041218: R-band optical observations
  44. GRB041218: Liverpool Telescope optical observations
  45. GRB041218: optical observations
  46. GRB041219: Confirmed NIR Afterglow
  47. GRB041218: Continued P60 Optical Observations
  48. Swift-BAT detection of the bright long burst GRB041219
  49. GRB 041218: Optical Observation
  50. GRB 041219: Infrared Afterglow Candidate
  51. GRB041219, BVRcIc field calibration
  52. GRB 041219: Infrared Afterglow Candidate
  53. GRB041218, BVRcIc field calibration
  54. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  55. GRB041219: P60 Optical Observations
  56. GRB 041219 - A long GRB detected by INTEGRAL
  57. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  58. GRB 041217: PROMPT Observations
  59. GRB041218: optical observations
  60. GRB041217: optical limit 30 min after GRB
  61. GRB 041218; optical candidate
  62. GRB 041218: Optical observations
  63. GRB 041217: LCO40 Optical Observations and Possible Candidates
  64. GRB 041218 - A long GRB detected by integral
  65. GRB041217: Optical Observations
  66. GRB041217: NIR and optical observations with REM
  67. GRB041217: P60 Optical Observations
  68. GRB041217: Infrared Observations
  69. GRB041217: The First GRB Located On-Board Swift
  70. GRB041211: Faulkes Telescope continued optical monitoring
  71. Optical Transient in Lynx not a GRB
  72. Optical transient (GRB?) in Lynx
  73. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  74. GRB041211: Continued P60 Observations
  75. GRB041211: RAPTOR observations
  76. GRB041211: Ashra Prototype optical observation
  77. GRB041211, Faulkes Telescope optical observation
  78. GRB041211, BVRcIc field calibration
  79. GRB041211,optical observation
  80. GRB 041211: Infrared Observations
  81. GRB 041211: KAIT observations
  82. GRB 041211: Optical follow-up in East Asian region
  83. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  84. GRB041211: P60 optical imaging
  85. GRB970815: Discovery of Optical Afterglow
  86. Distribution of IBAS Alerts for NON-GRB sources
  87. Triangulation of short GRB 041116 (large error box)
  88. GRB041015: Near-Infrared observations
  89. GRB 040924: Afterglow Color
  90. GRB 041006: GETS Optical Afterglow Observation
  91. Summary of the recent bursts from SGR 1806-20
  92. GRB 041006: Optical Observations
  93. GRB041006, late-time optical photometry
  94. GRB041015, optical observation in CrAO
  95. IBAS GRB Alert # 2034
  96. GRB041006: RTT150 Optical Observations
  97. GRB041015 : Multi epoch optical observations
  98. HST Observations: XRF 040701 and 040812
  99. Bright bursts from SGR1806-20
  100. GRB 041016: BOOTES-2 simultaneous observation

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