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

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