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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. GRB041223: optical and NIR observations with REM
  2. Swift-BAT Time History of GRB041219
  3. GRB 041219: TAROT optical observations
  4. GRB 041218: TAROT optical observations
  5. GRB 041223: J-band observations of the afterglow
  6. GRB 041223: Detection of Optical Transient with LCO40
  7. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  8. GRB 041219c: PROMPT Observations
  9. GRB041223: ROTSE-III Optical Observations
  10. GRB041223: Swift-BAT detection of a bright long burst
  11. GRB 041218: optical observations
  12. Very high activity of SGR 1806-20
  13. GRB 041219: Second Epoch WSRT Radio Observations
  14. GRB 041219: WSRT Radio Afterglow Detection
  15. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  16. GRB 041218: Optical observations
  17. GRB 041219 : optical follow-up observations
  18. GRB041220: Swift-BAT burst
  19. Deep RAPTOR observations during GRB 041219
  20. GRB 041218 Optical Observations
  21. GRB 041219 Optical Observations
  22. GRB041219c: Third Burst in One Day from Swift-BAT
  23. GRB041219: Optical Afterglow Detection
  24. GRB041219: Continued NIR Observations
  25. GRB041219b: A Swift-BAT burst
  26. GRB 041219 ,optical observation
  27. GRB 041219: Radio Afterglow Detection
  28. GRB 041218 : Radio Observations
  29. GRB 041218: R-band optical observations
  30. GRB041218: Liverpool Telescope optical observations
  31. GRB041218: optical observations
  32. GRB041219: Confirmed NIR Afterglow
  33. GRB041218: Continued P60 Optical Observations
  34. Swift-BAT detection of the bright long burst GRB041219
  35. GRB 041218: Optical Observation
  36. GRB 041219: Infrared Afterglow Candidate
  37. GRB041219, BVRcIc field calibration
  38. GRB 041219: Infrared Afterglow Candidate
  39. GRB041218, BVRcIc field calibration
  40. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  41. GRB041219: P60 Optical Observations
  42. GRB 041219 - A long GRB detected by INTEGRAL
  43. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  44. GRB 041217: PROMPT Observations
  45. GRB041218: optical observations
  46. GRB041217: optical limit 30 min after GRB
  47. GRB 041218; optical candidate
  48. GRB 041218: Optical observations
  49. GRB 041217: LCO40 Optical Observations and Possible Candidates
  50. GRB 041218 - A long GRB detected by integral
  51. GRB041217: Optical Observations
  52. GRB041217: NIR and optical observations with REM
  53. GRB041217: P60 Optical Observations
  54. GRB041217: Infrared Observations
  55. GRB041217: The First GRB Located On-Board Swift
  56. GRB041211: Faulkes Telescope continued optical monitoring
  57. Optical Transient in Lynx not a GRB
  58. Optical transient (GRB?) in Lynx
  59. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  60. GRB041211: Continued P60 Observations
  61. GRB041211: RAPTOR observations
  62. GRB041211: Ashra Prototype optical observation
  63. GRB041211, Faulkes Telescope optical observation
  64. GRB041211, BVRcIc field calibration
  65. GRB041211,optical observation
  66. GRB 041211: Infrared Observations
  67. GRB 041211: KAIT observations
  68. GRB 041211: Optical follow-up in East Asian region
  69. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  70. GRB041211: P60 optical imaging
  71. GRB970815: Discovery of Optical Afterglow
  72. Distribution of IBAS Alerts for NON-GRB sources
  73. Triangulation of short GRB 041116 (large error box)
  74. GRB041015: Near-Infrared observations
  75. GRB 040924: Afterglow Color
  76. GRB 041006: GETS Optical Afterglow Observation
  77. Summary of the recent bursts from SGR 1806-20
  78. GRB 041006: Optical Observations
  79. GRB041006, late-time optical photometry
  80. GRB041015, optical observation in CrAO
  81. IBAS GRB Alert # 2034
  82. GRB041006: RTT150 Optical Observations
  83. GRB041015 : Multi epoch optical observations
  84. HST Observations: XRF 040701 and 040812
  85. Bright bursts from SGR1806-20
  86. GRB 041016: BOOTES-2 simultaneous observation
  87. GRB041006: RTT150 Optical Observations
  88. GRB041016,optical observation
  89. GRB 041016: Optical limits
  90. GRB 041016: Optical limits in V, R, I
  91. GRB 041016:Optical limit during first minute
  92. GRB041016: MASTER: Optical observations
  93. GRB 041015: Optical Observations at Rikubetsu
  94. GRB041006: Near Infrared observations
  95. GRB 041016: Optical limit
  96. GRB 041015 R band observations
  97. GRB040924, BVRcIc field calibration
  98. GRB041015: MASTER: Optical observations
  99. GRB041015,optical observation
  100. GRB041006: Fading X-ray Afterglow Observed with Chandra

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