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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 050408: Properties of the Host Galaxy
  2. GRB 050408: Mercator Optical Observations
  3. GRB050408: Radio Observations
  4. GRB 050408: Swift XRT analysis
  5. GRB 050408, SMARTS optical/IR afterglow observations
  6. GRB 050408: Optical limit at 20 min after the burst
  7. GRB 050408, optical observations
  8. GRB050408: REM NIR and Optical observation
  9. GRB 050408: Moderate-resolution Gemini Spectroscopy
  10. GRB 050408,optical observation
  11. GRB 050408 Optical Observations
  12. GRB 050408: Emission and absorption redshift
  13. GRB 050408: Mercator Optical Observations
  14. GRB 050408: Magellan astrometry and photometry
  15. GRB 050408: First Optical observations with TFOSC at the RTT150
  16. GRB 050408: steepening of the optical decay
  17. GRB 050408: Optical afterglow confirmed
  18. GRB 050408: opitcal observation
  19. GRB 050408, optical observations
  20. GRB 050408 optical candidate
  21. GRB 050408: Swift XRT Position
  22. GRB 050408: ROTSE-III Optical Limits
  23. GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
  24. GRB050408: MASTER optical observations
  25. GRB050401: Radio Detection
  26. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  27. GRB 050406: Magellan optical observations
  28. GRB 050406: early Swift XRT analysis results
  29. GRB 050406 BAT refined analysis
  30. GRB 050406: Early observations with Swift-UVOT
  31. GRB 050406: Swift XRT Position
  32. Swift-BAT detection of GRB 050406
  33. Konus-Wind observation of GRB 050401
  34. GRB050401: Radio observation at 610 MHz with GMRT
  35. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  36. GRB 050401: VLT spectroscopic redshift
  37. GRB 050401 Optical Observations
  38. GRB050401: Maidanak optical observation
  39. GRB 050401 BAT refined analysis
  40. Very questionable identity of Swift-BAT GRB050402 (Trig=113225)
  41. GRB050401: TNG R-band observation
  42. GRB 050402A: IR Analysis
  43. GRB050402: XDSS counterpart
  44. GRB 050402A: IR Observations
  45. GRB 050402: Early observations with Swift-UVOT
  46. Swift Trigger 113225: P60 Observations
  47. GRB050401: ROTSE-III Detection of Prompt Optical Counterpart
  48. GRB 050401: Optical afterglow confirmed
  49. GRB 050401: Optical afterglow candidate
  50. Swift-BAT detection of GRB 050401
  51. GRB 050401: Prompt XRT position
  52. Retraction of three Swift GRB triggers
  53. GRB050331: No Afterglow Detected
  54. Swift-BAT detection of GRB 050331b
  55. GRB 050331: Swift UVOT Source
  56. Swift-BAT detection of GRB 050331
  57. GRB 050331: Swift XRT Position
  58. Swift Data Publicly Available Starting April 5, 2005
  59. GRB050319: radio observation
  60. Konus-Wind observation of GRB 050326
  61. GRB050326: optical limit
  62. GRB 050326: Early observations with Swift-UVOT
  63. GRB 050326 XMM-Newton observation
  64. GRB 050326 : Planned XMM-Newton observation
  65. GRB 050326: Swift XRT Position
  66. GRB050326: optical limit 33min before GRB
  67. GRB 050326 BAT refined analysis
  68. GRB050326: delayed XRT observation
  69. Swift-BAT detection of a bright GRB 050326
  70. GRB050319, optical observations
  71. GRB050319, color indices
  72. GRB050319: optical observation, March 20-22
  73. GRB050319: RTT150 Optical Observations
  74. Swift-BAT detection of a bright outburst from SGR1806-20
  75. Swift-BAT trigger 112060 is not a real GRB
  76. GRB 050319: Absorption redshift from the Nordic Optical Telescope
  77. GRB 050319: ROTSE-III Refined Analysis
  78. GRB 050318: Swift-BAT refined analysis
  79. Refined Swift XRT positions for GRB050315, GRB050318 and GRB050319
  80. GRB050319: VLA Observations
  81. GRB050319: radio observation
  82. GRB 050319 R band observations
  83. GRB 050319: Swift-UVOT detection of the afterglow
  84. GRB 050315: Variability Analysis of Swift BAT Time History
  85. GRB050319: Radio Observations
  86. GRB 050319: NIR afterglow candidate
  87. GRB 050319:Near IR afterglow
  88. GRB050319: BR optical photometry
  89. GRB 050318: SWIFT-UVOT refined analysis
  90. GRB 050318: Absorption redshift from Magellan
  91. GRB 050319: Optical observation
  92. GRB 050319 : Confirmation of optical afterglow decay
  93. GRB 050319: Swift-BAT refined analysis
  94. GRB050319,optical observation
  95. Swift Detection of GRB 050319
  96. GRB 050319: Detection of Possible Optical Counterpart
  97. GRB 050318: Swift/UVOT detection of afterglow emission
  98. GRB 050318: Magellan optical afterglow identification
  99. GRB050318: Swift XRT position
  100. RXTE Observations of GRB050318

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