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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: Mercator Optical Observations
  2. GRB 050408: Magellan astrometry and photometry
  3. GRB 050408: First Optical observations with TFOSC at the RTT150
  4. GRB 050408: steepening of the optical decay
  5. GRB 050408: Optical afterglow confirmed
  6. GRB 050408: opitcal observation
  7. GRB 050408, optical observations
  8. GRB 050408 optical candidate
  9. GRB 050408: Swift XRT Position
  10. GRB 050408: ROTSE-III Optical Limits
  11. GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
  12. GRB050408: MASTER optical observations
  13. GRB050401: Radio Detection
  14. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  15. GRB 050406: Magellan optical observations
  16. GRB 050406: early Swift XRT analysis results
  17. GRB 050406 BAT refined analysis
  18. GRB 050406: Early observations with Swift-UVOT
  19. GRB 050406: Swift XRT Position
  20. Swift-BAT detection of GRB 050406
  21. Konus-Wind observation of GRB 050401
  22. GRB050401: Radio observation at 610 MHz with GMRT
  23. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  24. GRB 050401: VLT spectroscopic redshift
  25. GRB 050401 Optical Observations
  26. GRB050401: Maidanak optical observation
  27. GRB 050401 BAT refined analysis
  28. Very questionable identity of Swift-BAT GRB050402 (Trig=113225)
  29. GRB050401: TNG R-band observation
  30. GRB 050402A: IR Analysis
  31. GRB050402: XDSS counterpart
  32. GRB 050402A: IR Observations
  33. GRB 050402: Early observations with Swift-UVOT
  34. Swift Trigger 113225: P60 Observations
  35. GRB050401: ROTSE-III Detection of Prompt Optical Counterpart
  36. GRB 050401: Optical afterglow confirmed
  37. GRB 050401: Optical afterglow candidate
  38. Swift-BAT detection of GRB 050401
  39. GRB 050401: Prompt XRT position
  40. Retraction of three Swift GRB triggers
  41. GRB050331: No Afterglow Detected
  42. Swift-BAT detection of GRB 050331b
  43. GRB 050331: Swift UVOT Source
  44. Swift-BAT detection of GRB 050331
  45. GRB 050331: Swift XRT Position
  46. Swift Data Publicly Available Starting April 5, 2005
  47. GRB050319: radio observation
  48. Konus-Wind observation of GRB 050326
  49. GRB050326: optical limit
  50. GRB 050326: Early observations with Swift-UVOT
  51. GRB 050326 XMM-Newton observation
  52. GRB 050326 : Planned XMM-Newton observation
  53. GRB 050326: Swift XRT Position
  54. GRB050326: optical limit 33min before GRB
  55. GRB 050326 BAT refined analysis
  56. GRB050326: delayed XRT observation
  57. Swift-BAT detection of a bright GRB 050326
  58. GRB050319, optical observations
  59. GRB050319, color indices
  60. GRB050319: optical observation, March 20-22
  61. GRB050319: RTT150 Optical Observations
  62. Swift-BAT detection of a bright outburst from SGR1806-20
  63. Swift-BAT trigger 112060 is not a real GRB
  64. GRB 050319: Absorption redshift from the Nordic Optical Telescope
  65. GRB 050319: ROTSE-III Refined Analysis
  66. GRB 050318: Swift-BAT refined analysis
  67. Refined Swift XRT positions for GRB050315, GRB050318 and GRB050319
  68. GRB050319: VLA Observations
  69. GRB050319: radio observation
  70. GRB 050319 R band observations
  71. GRB 050319: Swift-UVOT detection of the afterglow
  72. GRB 050315: Variability Analysis of Swift BAT Time History
  73. GRB050319: Radio Observations
  74. GRB 050319: NIR afterglow candidate
  75. GRB 050319:Near IR afterglow
  76. GRB050319: BR optical photometry
  77. GRB 050318: SWIFT-UVOT refined analysis
  78. GRB 050318: Absorption redshift from Magellan
  79. GRB 050319: Optical observation
  80. GRB 050319 : Confirmation of optical afterglow decay
  81. GRB 050319: Swift-BAT refined analysis
  82. GRB050319,optical observation
  83. Swift Detection of GRB 050319
  84. GRB 050319: Detection of Possible Optical Counterpart
  85. GRB 050318: Swift/UVOT detection of afterglow emission
  86. GRB 050318: Magellan optical afterglow identification
  87. GRB050318: Swift XRT position
  88. RXTE Observations of GRB050318
  89. Swift-BAT detection of GRB 050318
  90. GRB 050315, SMARTS optical afterglow decay
  91. GRB050223: analysis of the XMM-Newton observation
  92. GRB050316: MASTER before, simultanious and follow up optical
  93. GRB 050306: ROTSE-III early limits
  94. GRB050316: MASTER optical observations
  95. GRB 050315: Swift-BAT further refined analysis
  96. GRB 050315, SMARTS optical/IR afterglow observations
  97. GRB 050315 I-band observations
  98. GRB050315: Radio afterglow
  99. GRB 050315: Absorption redshift
  100. GRB 050315: Optical afterglow identification

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