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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. Retraction of three Swift GRB triggers
  2. GRB050331: No Afterglow Detected
  3. Swift-BAT detection of GRB 050331b
  4. GRB 050331: Swift UVOT Source
  5. Swift-BAT detection of GRB 050331
  6. GRB 050331: Swift XRT Position
  7. Swift Data Publicly Available Starting April 5, 2005
  8. GRB050319: radio observation
  9. Konus-Wind observation of GRB 050326
  10. GRB050326: optical limit
  11. GRB 050326: Early observations with Swift-UVOT
  12. GRB 050326 XMM-Newton observation
  13. GRB 050326 : Planned XMM-Newton observation
  14. GRB 050326: Swift XRT Position
  15. GRB050326: optical limit 33min before GRB
  16. GRB 050326 BAT refined analysis
  17. GRB050326: delayed XRT observation
  18. Swift-BAT detection of a bright GRB 050326
  19. GRB050319, optical observations
  20. GRB050319, color indices
  21. GRB050319: optical observation, March 20-22
  22. GRB050319: RTT150 Optical Observations
  23. Swift-BAT detection of a bright outburst from SGR1806-20
  24. Swift-BAT trigger 112060 is not a real GRB
  25. GRB 050319: Absorption redshift from the Nordic Optical Telescope
  26. GRB 050319: ROTSE-III Refined Analysis
  27. GRB 050318: Swift-BAT refined analysis
  28. Refined Swift XRT positions for GRB050315, GRB050318 and GRB050319
  29. GRB050319: VLA Observations
  30. GRB050319: radio observation
  31. GRB 050319 R band observations
  32. GRB 050319: Swift-UVOT detection of the afterglow
  33. GRB 050315: Variability Analysis of Swift BAT Time History
  34. GRB050319: Radio Observations
  35. GRB 050319: NIR afterglow candidate
  36. GRB 050319:Near IR afterglow
  37. GRB050319: BR optical photometry
  38. GRB 050318: SWIFT-UVOT refined analysis
  39. GRB 050318: Absorption redshift from Magellan
  40. GRB 050319: Optical observation
  41. GRB 050319 : Confirmation of optical afterglow decay
  42. GRB 050319: Swift-BAT refined analysis
  43. GRB050319,optical observation
  44. Swift Detection of GRB 050319
  45. GRB 050319: Detection of Possible Optical Counterpart
  46. GRB 050318: Swift/UVOT detection of afterglow emission
  47. GRB 050318: Magellan optical afterglow identification
  48. GRB050318: Swift XRT position
  49. RXTE Observations of GRB050318
  50. Swift-BAT detection of GRB 050318
  51. GRB 050315, SMARTS optical afterglow decay
  52. GRB050223: analysis of the XMM-Newton observation
  53. GRB050316: MASTER before, simultanious and follow up optical
  54. GRB 050306: ROTSE-III early limits
  55. GRB050316: MASTER optical observations
  56. GRB 050315: Swift-BAT further refined analysis
  57. GRB 050315, SMARTS optical/IR afterglow observations
  58. GRB 050315 I-band observations
  59. GRB050315: Radio afterglow
  60. GRB 050315: Absorption redshift
  61. GRB 050315: Optical afterglow identification
  62. GRB050315: Swift-BAT Refined analysis
  63. Non-detection of GRB050315 in ATCA Radio Observations
  64. GRB 050315: Swift XRT Position
  65. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  66. GRB 050315: Early Observations with Swift/UVOT
  67. Swift-BAT detection of GRB 050315
  68. GRB050223: No XMM-Newton OM detection of afterglow emission
  69. GRB 050306: Radio Observations
  70. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  71. GRB050309: CONCAM pre-trigger and trigger coincident optical
  72. GRB 050306: optical afterglow
  73. GRB 050126: Redshift determination
  74. Swift-BAT trigger 107873: No Swift XRT counterpart
  75. GRB 050306: Confirmation of X-ray afterglow
  76. GRB 050309, Early optical limits from RAPTOR
  77. GRB 050306: further TAROT optical data
  78. GRB050309: Early optical limit from P60
  79. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  80. GRB 050309 : Lulin R-band observation
  81. Swift 107873: P60 Optical Observations
  82. GRB 050306: CORRECTION to date of observation
  83. GRB 050306: R-band observations
  84. GRB 050306: No Swift UVOT Optical Counterpart Detected
  85. GRB 050306: REM optical-infrared observations
  86. GRB 050306: Possible X-ray Afterglow Position from the Swift
  87. Swift trigger 107518: optical observation
  88. GRB 050306: TAROT optical observations
  89. GRB 050306,optical observation
  90. GRB 050306: Swift-BAT detection of a long burst
  91. Ongoing activity of SGR 1806-20 after the giant flare
  92. GRB050215B: Late-Time Swift UVOT Observations
  93. GRB 050126: Confirmation of the NIR afterglow candidate
  94. PROMPT VRcIc Observations of GRB 050223
  95. XRF/GRB 050215B: Radio Observations
  96. XMM-Newton Images of GRB 050223
  97. GRB 050219b: candidate NIR afterglow
  98. IBAS GRB Alert #2321
  99. Confirmed XRF nature for GRB050215b
  100. GRB 050223: optical observations

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