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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 050412: Subaru observations
  2. GRB 050408: RTT150 optical observations
  3. GRB050408: optical observation
  4. GRB 050412: PROMPT VRcIc Observations
  5. GRB 050408: Kuiper 1.5m observations
  6. GRB 050412: optical limit
  7. GRB 050412: optical observations
  8. GRB 050408: refined XRT analysis, no jet break seen yet
  9. GRB 050412: early Swift XRT analysis results
  10. GRB 050412 : XingLong optical observation
  11. GRB 050412: Swift-BAT refined analysis
  12. GRB 050412: ANU 2.3m observations
  13. GRB 050412: Early Optical/Ultraviolet Observations with
  14. GRB 050412: retraction of UVOT transient report
  15. GRB 050412: UVOT transient not in XRT error circle
  16. GRB 050408: SDSS Field Calibration
  17. GRB 050412: Optical limit
  18. GRB 050412: LCO Optical Observations
  19. GRB 050412: Optical observations
  20. GRB050412: P60 Observations
  21. GRB 050412: Swift XRT Position
  22. GRB050412: optical limit before and during GRB
  23. GRB 050412: LCO optical observations
  24. GRB050412: ROTSE-III Optical Limits
  25. Swift-BAT Detection of GRB 050412: A Bright, Long Burst
  26. GRB 050412: IR and Optical observations
  27. GRB 050412: IR Observations
  28. GRB050408: Radio Observations
  29. GRB 050401: Optical limit
  30. GRB 050408: Optical limit
  31. GRB050410: P60 Observations
  32. GRB 050410: Early Optical/Ultraviolet Observations with Swift/UVOT
  33. GRB 050410, optical observations
  34. GRB 050408: PROMPT VRcIc Observations
  35. GRB 050408: Early Optical/Ultraviolet Observations with Swift/UVOT
  36. GRB 050410 R band Optical Observations
  37. GRB050410 : Null detection report
  38. GRB 050410, optical observations
  39. GRB050410: Radio Observations
  40. GRB 050408: Swift XRT measurement of possible jet break
  41. GRB050410: MASTER optical observations
  42. GRB 050410: Early observations with Swift-UVOT
  43. Swift-BAT detection of GRB 050410
  44. GRB 050410: Swift XRT Position
  45. GRB 050408: Retraction of Proposed Host Galaxy
  46. GRB 050408: Inconsistency of host galaxy identification
  47. GRB 050408: Subaru Observations
  48. GRB 050408: WIDGET simultaneous optical observations
  49. GRB 050408: SOAR UBVRc Observations
  50. GRB 050408: Properties of the Host Galaxy
  51. GRB 050408: Mercator Optical Observations
  52. GRB050408: Radio Observations
  53. GRB 050408: Swift XRT analysis
  54. GRB 050408, SMARTS optical/IR afterglow observations
  55. GRB 050408: Optical limit at 20 min after the burst
  56. GRB 050408, optical observations
  57. GRB050408: REM NIR and Optical observation
  58. GRB 050408: Moderate-resolution Gemini Spectroscopy
  59. GRB 050408,optical observation
  60. GRB 050408 Optical Observations
  61. GRB 050408: Emission and absorption redshift
  62. GRB 050408: Mercator Optical Observations
  63. GRB 050408: Magellan astrometry and photometry
  64. GRB 050408: First Optical observations with TFOSC at the RTT150
  65. GRB 050408: steepening of the optical decay
  66. GRB 050408: Optical afterglow confirmed
  67. GRB 050408: opitcal observation
  68. GRB 050408, optical observations
  69. GRB 050408 optical candidate
  70. GRB 050408: Swift XRT Position
  71. GRB 050408: ROTSE-III Optical Limits
  72. GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
  73. GRB050408: MASTER optical observations
  74. GRB050401: Radio Detection
  75. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  76. GRB 050406: Magellan optical observations
  77. GRB 050406: early Swift XRT analysis results
  78. GRB 050406 BAT refined analysis
  79. GRB 050406: Early observations with Swift-UVOT
  80. GRB 050406: Swift XRT Position
  81. Swift-BAT detection of GRB 050406
  82. Konus-Wind observation of GRB 050401
  83. GRB050401: Radio observation at 610 MHz with GMRT
  84. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  85. GRB 050401: VLT spectroscopic redshift
  86. GRB 050401 Optical Observations
  87. GRB050401: Maidanak optical observation
  88. GRB 050401 BAT refined analysis
  89. Very questionable identity of Swift-BAT GRB050402 (Trig=113225)
  90. GRB050401: TNG R-band observation
  91. GRB 050402A: IR Analysis
  92. GRB050402: XDSS counterpart
  93. GRB 050402A: IR Observations
  94. GRB 050402: Early observations with Swift-UVOT
  95. Swift Trigger 113225: P60 Observations
  96. GRB050401: ROTSE-III Detection of Prompt Optical Counterpart
  97. GRB 050401: Optical afterglow confirmed
  98. GRB 050401: Optical afterglow candidate
  99. Swift-BAT detection of GRB 050401
  100. GRB 050401: Prompt XRT position

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