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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"

3402 results found.

  1. GRB 210618A: Swift-XRT afterglow detection
  2. GRB 210619B: Swift-XRT refined Analysis
  3. GRB 210618A: Swift-XRT observations
  4. Swift ToO Observations of HAWC transient J0020+3108
  5. GRB 210605B: Swift-XRT afterglow detection
  6. GRB 210610B: Swift-XRT refined Analysis
  7. GRB 210610A: Swift-XRT refined Analysis
  8. GRB 210606A: Swift-XRT afterglow detection
  9. GRB 210605B: Swift-XRT observations
  10. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  11. Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
  12. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  13. GRB 210527A: Swift-XRT refined Analysis
  14. GRB 210520A: Swift-XRT observations
  15. GRB210413B: further Swift-XRT observations
  16. GRB 210517A: Swift-XRT refined Analysis
  17. GRB 210514A: Swift/UVOT Upper Limits
  18. GRB 210515C: Swift-XRT refined Analysis
  19. GRB 210514A: Swift-XRT refined Analysis
  20. GRB 210514A: update on the BAT trigger time and burst duration
  21. GRB 210509A: Swift-XRT refined Analysis
  22. GRB 210506A: Swift-XRT observations
  23. GRB 210504A: Swift-XRT refined Analysis
  24. GRB 210413B: Swift/UVOT Observations
  25. GRB 210323B: Swift-XRT observations
  26. Swift Trigger 1045571 is not a GRB
  27. GRB 210421B: Swift-XRT observations
  28. GRB 210420B: Swift-XRT refined Analysis
  29. GRB 210421A: Swift-XRT refined Analysis
  30. GRB 210419A: Swift-XRT refined Analysis
  31. GRB 210413B: Swift-XRT observations
  32. GRB 210411C: Swift-XRT refined Analysis
  33. GRB 210410A: Swift-XRT refined Analysis
  34. GRB 210406A: Swift-XRT observations
  35. GRB 210402A: Swift-XRT refined Analysis
  36. GRB 210323A: Swift-XRT refined Analysis
  37. GRB 210321A: Swift-XRT refined Analysis
  38. GRB 210318A: Swift-XRT refined Analysis
  39. GRB210318B: Swift detection of a burst
  40. GRB 171205A: Continued ATCA observations
  41. GRB 210305A: Swift-XRT refined Analysis
  42. GRB 210307A: Swift-XRT refined Analysis
  43. GRB 210306A: Swift-XRT refined Analysis
  44. GRB 210226A: Swift-XRT refined Analysis
  45. GRB 210218A: Swift-XRT confirmation of afterglow
  46. GRB 210222B: Swift-XRT refined Analysis
  47. GRB 210218A: Swift/UVOT observations
  48. GRB 210218A: Swift-XRT observations
  49. GRB 210217A: Swift-XRT refined Analysis
  50. GRB 210212A: Swift-XRT refined Analysis
  51. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  52. GRB 210211A: Swift-XRT refined Analysis
  53. Swift-XRT observations of IceCube-210210A
  54. GRB 210210A: Swift-XRT refined Analysis
  55. GRB 210209A: Swift-XRT refined Analysis
  56. GRB 210207B: Swift-XRT refined Analysis
  57. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  58. GRB 210205A: Swift-XRT refined Analysis
  59. Continued Chandra observations of GW170817 at ~3.3 years since merger
  60. GRB 140330A: Swift-XRT refined Analysis
  61. GRB 140320B: Swift-XRT refined Analysis
  62. GRB 140402A: Swift-XRT refined Analysis
  63. GRB 140104B: Swift-XRT refined Analysis
  64. GRB 201221D: near-infrared observation with LBT
  65. GRB 210112A: Swift-XRT refined Analysis
  66. Correction to GCN 29278: GRB 201216C XRT refined analysis
  67. GRB 201216C: Swift-XRT refined Analysis
  68. GRB 210102B: further Swift-XRT observations
  69. GW170817: HST observations at 3.4 years from merger
  70. GRB 210104A: Swift-XRT refined Analysis
  71. GRB 210104B: Swift-XRT refined Analysis
  72. GRB 210102B: Swift-XRT observations
  73. GRB 201227A: Swift-XRT observations
  74. GRB 201229A: Swift-XRT refined Analysis
  75. GRB 201223A: Swift-XRT refined Analysis
  76. Swift-XRT observations of Icecube 201222A
  77. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  78. GRB 201216A - further Swift-XRT observations
  79. GRB 201221D: Swift-XRT refined Analysis
  80. GRB 201221A: Swift-XRT refined Analysis
  81. GRB 201214A: Swift-XRT afterglow detection
  82. GRB 201216A: Swift-XRT observations
  83. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  84. GRB 201214B: Swift-XRT observations
  85. GRB 201214A: Swift-XRT observations
  86. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  87. Long-lasting X-ray emission from GW170817 detected by Chandra
  88. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  89. GRB 201208A: Swift-XRT afterglow detection
  90. GRB 201209A: Swift-XRT refined Analysis
  91. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  92. GRB 201203A: Swift-XRT afterglow detection
  93. GRB 201128B: Swift-XRT observations
  94. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  95. Swift-XRT observations of IceCube 201130A
  96. GRB 201128A: Swift-XRT refined Analysis
  97. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  98. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  99. GRB 201116A: Swift-XRT afterglow detection
  100. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert

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