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

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