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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. GRB041224: ROTSE-III Optical Observations
  2. GRB 041224: near-infrared observations with REM
  3. GRB 041223: XRT afterglow spectrum and light curve
  4. GRB 041223 Fluence measured by Swift-BAT
  5. GRB041224: Swift-BAT detection of a soft burst
  6. GRB041223: optical and NIR observations with REM
  7. Swift-BAT Time History of GRB041219
  8. GRB 041219: TAROT optical observations
  9. GRB 041218: TAROT optical observations
  10. GRB 041223: J-band observations of the afterglow
  11. GRB 041223: Detection of Optical Transient with LCO40
  12. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  13. GRB 041219c: PROMPT Observations
  14. GRB041223: ROTSE-III Optical Observations
  15. GRB041223: Swift-BAT detection of a bright long burst
  16. GRB 041218: optical observations
  17. Very high activity of SGR 1806-20
  18. GRB 041219: Second Epoch WSRT Radio Observations
  19. GRB 041219: WSRT Radio Afterglow Detection
  20. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  21. GRB 041218: Optical observations
  22. GRB 041219 : optical follow-up observations
  23. GRB041220: Swift-BAT burst
  24. Deep RAPTOR observations during GRB 041219
  25. GRB 041218 Optical Observations
  26. GRB 041219 Optical Observations
  27. GRB041219c: Third Burst in One Day from Swift-BAT
  28. GRB041219: Optical Afterglow Detection
  29. GRB041219: Continued NIR Observations
  30. GRB041219b: A Swift-BAT burst
  31. GRB 041219 ,optical observation
  32. GRB 041219: Radio Afterglow Detection
  33. GRB 041218 : Radio Observations
  34. GRB 041218: R-band optical observations
  35. GRB041218: Liverpool Telescope optical observations
  36. GRB041218: optical observations
  37. GRB041219: Confirmed NIR Afterglow
  38. GRB041218: Continued P60 Optical Observations
  39. Swift-BAT detection of the bright long burst GRB041219
  40. GRB 041218: Optical Observation
  41. GRB 041219: Infrared Afterglow Candidate
  42. GRB041219, BVRcIc field calibration
  43. GRB 041219: Infrared Afterglow Candidate
  44. GRB041218, BVRcIc field calibration
  45. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  46. GRB041219: P60 Optical Observations
  47. GRB 041219 - A long GRB detected by INTEGRAL
  48. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  49. GRB 041217: PROMPT Observations
  50. GRB041218: optical observations
  51. GRB041217: optical limit 30 min after GRB
  52. GRB 041218; optical candidate
  53. GRB 041218: Optical observations
  54. GRB 041217: LCO40 Optical Observations and Possible Candidates
  55. GRB 041218 - A long GRB detected by integral
  56. GRB041217: Optical Observations
  57. GRB041217: NIR and optical observations with REM
  58. GRB041217: P60 Optical Observations
  59. GRB041217: Infrared Observations
  60. GRB041217: The First GRB Located On-Board Swift
  61. GRB041211: Faulkes Telescope continued optical monitoring
  62. Optical Transient in Lynx not a GRB
  63. Optical transient (GRB?) in Lynx
  64. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  65. GRB041211: Continued P60 Observations
  66. GRB041211: RAPTOR observations
  67. GRB041211: Ashra Prototype optical observation
  68. GRB041211, Faulkes Telescope optical observation
  69. GRB041211, BVRcIc field calibration
  70. GRB041211,optical observation
  71. GRB 041211: Infrared Observations
  72. GRB 041211: KAIT observations
  73. GRB 041211: Optical follow-up in East Asian region
  74. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  75. GRB041211: P60 optical imaging
  76. GRB970815: Discovery of Optical Afterglow
  77. Distribution of IBAS Alerts for NON-GRB sources
  78. Triangulation of short GRB 041116 (large error box)
  79. GRB041015: Near-Infrared observations
  80. GRB 040924: Afterglow Color
  81. GRB 041006: GETS Optical Afterglow Observation
  82. Summary of the recent bursts from SGR 1806-20
  83. GRB 041006: Optical Observations
  84. GRB041006, late-time optical photometry
  85. GRB041015, optical observation in CrAO
  86. IBAS GRB Alert # 2034
  87. GRB041006: RTT150 Optical Observations
  88. GRB041015 : Multi epoch optical observations
  89. HST Observations: XRF 040701 and 040812
  90. Bright bursts from SGR1806-20
  91. GRB 041016: BOOTES-2 simultaneous observation
  92. GRB041006: RTT150 Optical Observations
  93. GRB041016,optical observation
  94. GRB 041016: Optical limits
  95. GRB 041016: Optical limits in V, R, I
  96. GRB 041016:Optical limit during first minute
  97. GRB041016: MASTER: Optical observations
  98. GRB 041015: Optical Observations at Rikubetsu
  99. GRB041006: Near Infrared observations
  100. GRB 041016: Optical limit

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