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

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