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

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