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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. GRB050416: Maidanak optical observations
  2. GRB 050416: Swift-BAT refined analysis
  3. GRB 050416: ART observations
  4. GRB 050416,optical observation
  5. GRB 050416: KAIT observations
  6. GRB050416: P200 NIR Observations
  7. GRB 050416: Swift XRT Position
  8. GRB 050416: Radio observations
  9. Confirmation of OT for GRB050416
  10. GRB050416: P60 Afterglow Candidate
  11. Swift BAT/XRT Detection of GRB 050416
  12. GRB 050412: Subaru observations
  13. GRB 050408: RTT150 optical observations
  14. GRB050408: optical observation
  15. GRB 050412: PROMPT VRcIc Observations
  16. GRB 050408: Kuiper 1.5m observations
  17. GRB 050412: optical limit
  18. GRB 050412: optical observations
  19. GRB 050408: refined XRT analysis, no jet break seen yet
  20. GRB 050412: early Swift XRT analysis results
  21. GRB 050412 : XingLong optical observation
  22. GRB 050412: Swift-BAT refined analysis
  23. GRB 050412: ANU 2.3m observations
  24. GRB 050412: Early Optical/Ultraviolet Observations with
  25. GRB 050412: retraction of UVOT transient report
  26. GRB 050412: UVOT transient not in XRT error circle
  27. GRB 050408: SDSS Field Calibration
  28. GRB 050412: Optical limit
  29. GRB 050412: LCO Optical Observations
  30. GRB 050412: Optical observations
  31. GRB050412: P60 Observations
  32. GRB 050412: Swift XRT Position
  33. GRB050412: optical limit before and during GRB
  34. GRB 050412: LCO optical observations
  35. GRB050412: ROTSE-III Optical Limits
  36. Swift-BAT Detection of GRB 050412: A Bright, Long Burst
  37. GRB 050412: IR and Optical observations
  38. GRB 050412: IR Observations
  39. GRB050408: Radio Observations
  40. GRB 050401: Optical limit
  41. GRB 050408: Optical limit
  42. GRB050410: P60 Observations
  43. GRB 050410: Early Optical/Ultraviolet Observations with Swift/UVOT
  44. GRB 050410, optical observations
  45. GRB 050408: PROMPT VRcIc Observations
  46. GRB 050408: Early Optical/Ultraviolet Observations with Swift/UVOT
  47. GRB 050410 R band Optical Observations
  48. GRB050410 : Null detection report
  49. GRB 050410, optical observations
  50. GRB050410: Radio Observations
  51. GRB 050408: Swift XRT measurement of possible jet break
  52. GRB050410: MASTER optical observations
  53. GRB 050410: Early observations with Swift-UVOT
  54. Swift-BAT detection of GRB 050410
  55. GRB 050410: Swift XRT Position
  56. GRB 050408: Retraction of Proposed Host Galaxy
  57. GRB 050408: Inconsistency of host galaxy identification
  58. GRB 050408: Subaru Observations
  59. GRB 050408: WIDGET simultaneous optical observations
  60. GRB 050408: SOAR UBVRc Observations
  61. GRB 050408: Properties of the Host Galaxy
  62. GRB 050408: Mercator Optical Observations
  63. GRB050408: Radio Observations
  64. GRB 050408: Swift XRT analysis
  65. GRB 050408, SMARTS optical/IR afterglow observations
  66. GRB 050408: Optical limit at 20 min after the burst
  67. GRB 050408, optical observations
  68. GRB050408: REM NIR and Optical observation
  69. GRB 050408: Moderate-resolution Gemini Spectroscopy
  70. GRB 050408,optical observation
  71. GRB 050408 Optical Observations
  72. GRB 050408: Emission and absorption redshift
  73. GRB 050408: Mercator Optical Observations
  74. GRB 050408: Magellan astrometry and photometry
  75. GRB 050408: First Optical observations with TFOSC at the RTT150
  76. GRB 050408: steepening of the optical decay
  77. GRB 050408: Optical afterglow confirmed
  78. GRB 050408: opitcal observation
  79. GRB 050408, optical observations
  80. GRB 050408 optical candidate
  81. GRB 050408: Swift XRT Position
  82. GRB 050408: ROTSE-III Optical Limits
  83. GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
  84. GRB050408: MASTER optical observations
  85. GRB050401: Radio Detection
  86. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  87. GRB 050406: Magellan optical observations
  88. GRB 050406: early Swift XRT analysis results
  89. GRB 050406 BAT refined analysis
  90. GRB 050406: Early observations with Swift-UVOT
  91. GRB 050406: Swift XRT Position
  92. Swift-BAT detection of GRB 050406
  93. Konus-Wind observation of GRB 050401
  94. GRB050401: Radio observation at 610 MHz with GMRT
  95. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  96. GRB 050401: VLT spectroscopic redshift
  97. GRB 050401 Optical Observations
  98. GRB050401: Maidanak optical observation
  99. GRB 050401 BAT refined analysis
  100. Very questionable identity of Swift-BAT GRB050402 (Trig=113225)

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