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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"

3036 results found.

  1. GRB 201216C: Swift-XRT refined Analysis
  2. GRB 210102B: further Swift-XRT observations
  3. GW170817: HST observations at 3.4 years from merger
  4. GRB 210104A: Swift-XRT refined Analysis
  5. GRB 210104B: Swift-XRT refined Analysis
  6. GRB 210102B: Swift-XRT observations
  7. GRB 201227A: Swift-XRT observations
  8. GRB 201229A: Swift-XRT refined Analysis
  9. GRB 201223A: Swift-XRT refined Analysis
  10. Swift-XRT observations of Icecube 201222A
  11. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  12. GRB 201216A - further Swift-XRT observations
  13. GRB 201221D: Swift-XRT refined Analysis
  14. GRB 201221A: Swift-XRT refined Analysis
  15. GRB 201214A: Swift-XRT afterglow detection
  16. GRB 201216A: Swift-XRT observations
  17. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  18. GRB 201214B: Swift-XRT observations
  19. GRB 201214A: Swift-XRT observations
  20. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  21. Long-lasting X-ray emission from GW170817 detected by Chandra
  22. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  23. GRB 201208A: Swift-XRT afterglow detection
  24. GRB 201209A: Swift-XRT refined Analysis
  25. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  26. GRB 201203A: Swift-XRT afterglow detection
  27. GRB 201128B: Swift-XRT observations
  28. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  29. Swift-XRT observations of IceCube 201130A
  30. GRB 201128A: Swift-XRT refined Analysis
  31. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  32. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  33. GRB 201116A: Swift-XRT afterglow detection
  34. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  35. Swift-XRT observations of IceCube 201114A
  36. GRB 201104A: Swift-XRT observations
  37. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  38. GRB 201015A: Swift-XRT late time observations
  39. GRB 201104B: Swift-XRT refined Analysis
  40. Fermi GRB 201104A: Global MASTER-Net observations report
  41. IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
  42. GRB 201029A: Swift-XRT refined Analysis
  43. GRB 201027A: Swift-XRT refined Analysis
  44. GRB 201026A: Swift-XRT refined Analysis
  45. GRB201024A: rebrightening after initial steep decline
  46. GRB 201024A: Swift-XRT refined Analysis
  47. GRB 201021C: Swift-XRT refined Analysis
  48. GRB 201020B: Swift-XRT afterglow detection
  49. Swift-XRT observations of IceCube 201021A
  50. GRB 201020A: Swift-XRT refined Analysis
  51. GRB 201017A: Swift-XRT refined Analysis
  52. GRB 201015A: Swift-XRT refined Analysis
  53. GRB 201008A: Swift-XRT afterglow detection
  54. GRB 201014A: Swift-XRT refined Analysis
  55. Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
  56. GRB 201013A: Swift-XRT refined Analysis
  57. GRB 201006A: Chandra upper limit on the X-ray afterglow
  58. GRB 201008A: Swift-XRT observations
  59. IceCube-200926A: Upper limits from Insight-HXMT Observations
  60. Swift-XRT observations of IceCube 201007A
  61. GRB 201006A: Swift-XRT refined Analysis
  62. GRB 201001A: Swift-XRT refined Analysis
  63. Swift-XRT observations of IceCube 200929A
  64. Swift-XRT observations of IceCube 200926A
  65. GRB 200925B: Swift-XRT refined analysis update
  66. GRB 200925B: Swift-XRT refined Analysis
  67. GRB 200922A: Swift-XRT refined Analysis
  68. GRB 200914A: Swift-XRT further observations
  69. Swift-XRT observations of IceCube 200916A
  70. GRB 200917A: Swift-XRT refined Analysis
  71. Swift-XRT observations of IceCube 200911A
  72. GRB 200914A: Swift-XRT observations
  73. GRB 200907B: Swift-XRT refined Analysis
  74. GRB 200906A: LBT near-infrared upper limit
  75. GRB 200906A: Swift-XRT refined Analysis
  76. GRB 200901B: Swift-XRT refined Analysis
  77. GRB 200901A: Swift-XRT refined Analysis
  78. GRB 200901A: Swift-XRT observations
  79. GRB 200829A: Swift-XRT refined Analysis
  80. GRB 200826A: Swift-XRT afterglow detection
  81. Swift Trigger 992444 is due to detector noise
  82. Swift Trigger 992444: a possible GRB 200821A
  83. GRB 200819A: Swift-XRT refined Analysis
  84. Swift Trigger 990358 is due to detector noise
  85. Swift Trigger 989458 is due to detector noise
  86. GRB 200809B: Swift-XRT afterglow detection
  87. GRB 200806A: Swift-XRT refined Analysis
  88. GRB 200803A: Swift-XRT afterglow detection
  89. GRB 200729A: Swift-XRT refined Analysis
  90. GRB 200714E: Swift-XRT afterglow detection
  91. GRB 200716C: Swift-XRT refined analysis correction
  92. GRB 200716C: Swift-XRT refined Analysis
  93. GRB 200715A: Swift-XRT afterglow detection
  94. GRB 200714E: Swift-XRT observations
  95. GRB 200713A: Swift-XRT refined Analysis
  96. GRB 200711A: Swift-XRT refined Analysis
  97. GRB 200709B/HAWC-200907A: Swift-XRT further observations
  98. GRB 200709B: Swift-XRT observations
  99. GRB 200630A: Swift-XRT refined Analysis
  100. GRB 200623A: Swift XRT further observations

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