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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. GRB050412: ROTSE-III Optical Limits
  2. Swift-BAT Detection of GRB 050412: A Bright, Long Burst
  3. GRB 050412: IR and Optical observations
  4. GRB 050412: IR Observations
  5. GRB050408: Radio Observations
  6. GRB 050401: Optical limit
  7. GRB 050408: Optical limit
  8. GRB050410: P60 Observations
  9. GRB 050410: Early Optical/Ultraviolet Observations with Swift/UVOT
  10. GRB 050410, optical observations
  11. GRB 050408: PROMPT VRcIc Observations
  12. GRB 050408: Early Optical/Ultraviolet Observations with Swift/UVOT
  13. GRB 050410 R band Optical Observations
  14. GRB050410 : Null detection report
  15. GRB 050410, optical observations
  16. GRB050410: Radio Observations
  17. GRB 050408: Swift XRT measurement of possible jet break
  18. GRB050410: MASTER optical observations
  19. GRB 050410: Early observations with Swift-UVOT
  20. Swift-BAT detection of GRB 050410
  21. GRB 050410: Swift XRT Position
  22. GRB 050408: Retraction of Proposed Host Galaxy
  23. GRB 050408: Inconsistency of host galaxy identification
  24. GRB 050408: Subaru Observations
  25. GRB 050408: WIDGET simultaneous optical observations
  26. GRB 050408: SOAR UBVRc Observations
  27. GRB 050408: Properties of the Host Galaxy
  28. GRB 050408: Mercator Optical Observations
  29. GRB050408: Radio Observations
  30. GRB 050408: Swift XRT analysis
  31. GRB 050408, SMARTS optical/IR afterglow observations
  32. GRB 050408: Optical limit at 20 min after the burst
  33. GRB 050408, optical observations
  34. GRB050408: REM NIR and Optical observation
  35. GRB 050408: Moderate-resolution Gemini Spectroscopy
  36. GRB 050408,optical observation
  37. GRB 050408 Optical Observations
  38. GRB 050408: Emission and absorption redshift
  39. GRB 050408: Mercator Optical Observations
  40. GRB 050408: Magellan astrometry and photometry
  41. GRB 050408: First Optical observations with TFOSC at the RTT150
  42. GRB 050408: steepening of the optical decay
  43. GRB 050408: Optical afterglow confirmed
  44. GRB 050408: opitcal observation
  45. GRB 050408, optical observations
  46. GRB 050408 optical candidate
  47. GRB 050408: Swift XRT Position
  48. GRB 050408: ROTSE-III Optical Limits
  49. GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
  50. GRB050408: MASTER optical observations
  51. GRB050401: Radio Detection
  52. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  53. GRB 050406: Magellan optical observations
  54. GRB 050406: early Swift XRT analysis results
  55. GRB 050406 BAT refined analysis
  56. GRB 050406: Early observations with Swift-UVOT
  57. GRB 050406: Swift XRT Position
  58. Swift-BAT detection of GRB 050406
  59. Konus-Wind observation of GRB 050401
  60. GRB050401: Radio observation at 610 MHz with GMRT
  61. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  62. GRB 050401: VLT spectroscopic redshift
  63. GRB 050401 Optical Observations
  64. GRB050401: Maidanak optical observation
  65. GRB 050401 BAT refined analysis
  66. Very questionable identity of Swift-BAT GRB050402 (Trig=113225)
  67. GRB050401: TNG R-band observation
  68. GRB 050402A: IR Analysis
  69. GRB050402: XDSS counterpart
  70. GRB 050402A: IR Observations
  71. GRB 050402: Early observations with Swift-UVOT
  72. Swift Trigger 113225: P60 Observations
  73. GRB050401: ROTSE-III Detection of Prompt Optical Counterpart
  74. GRB 050401: Optical afterglow confirmed
  75. GRB 050401: Optical afterglow candidate
  76. Swift-BAT detection of GRB 050401
  77. GRB 050401: Prompt XRT position
  78. Retraction of three Swift GRB triggers
  79. GRB050331: No Afterglow Detected
  80. Swift-BAT detection of GRB 050331b
  81. GRB 050331: Swift UVOT Source
  82. Swift-BAT detection of GRB 050331
  83. GRB 050331: Swift XRT Position
  84. Swift Data Publicly Available Starting April 5, 2005
  85. GRB050319: radio observation
  86. Konus-Wind observation of GRB 050326
  87. GRB050326: optical limit
  88. GRB 050326: Early observations with Swift-UVOT
  89. GRB 050326 XMM-Newton observation
  90. GRB 050326 : Planned XMM-Newton observation
  91. GRB 050326: Swift XRT Position
  92. GRB050326: optical limit 33min before GRB
  93. GRB 050326 BAT refined analysis
  94. GRB050326: delayed XRT observation
  95. Swift-BAT detection of a bright GRB 050326
  96. GRB050319, optical observations
  97. GRB050319, color indices
  98. GRB050319: optical observation, March 20-22
  99. GRB050319: RTT150 Optical Observations
  100. Swift-BAT detection of a bright outburst from SGR1806-20

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