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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"

3403 results found.

  1. GRB 210622A: Swift-XRT observations
  2. GRB 210618A: Swift-XRT afterglow detection
  3. GRB 210619B: Swift-XRT refined Analysis
  4. GRB 210618A: Swift-XRT observations
  5. Swift ToO Observations of HAWC transient J0020+3108
  6. GRB 210605B: Swift-XRT afterglow detection
  7. GRB 210610B: Swift-XRT refined Analysis
  8. GRB 210610A: Swift-XRT refined Analysis
  9. GRB 210606A: Swift-XRT afterglow detection
  10. GRB 210605B: Swift-XRT observations
  11. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  12. Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
  13. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  14. GRB 210527A: Swift-XRT refined Analysis
  15. GRB 210520A: Swift-XRT observations
  16. GRB210413B: further Swift-XRT observations
  17. GRB 210517A: Swift-XRT refined Analysis
  18. GRB 210514A: Swift/UVOT Upper Limits
  19. GRB 210515C: Swift-XRT refined Analysis
  20. GRB 210514A: Swift-XRT refined Analysis
  21. GRB 210514A: update on the BAT trigger time and burst duration
  22. GRB 210509A: Swift-XRT refined Analysis
  23. GRB 210506A: Swift-XRT observations
  24. GRB 210504A: Swift-XRT refined Analysis
  25. GRB 210413B: Swift/UVOT Observations
  26. GRB 210323B: Swift-XRT observations
  27. Swift Trigger 1045571 is not a GRB
  28. GRB 210421B: Swift-XRT observations
  29. GRB 210420B: Swift-XRT refined Analysis
  30. GRB 210421A: Swift-XRT refined Analysis
  31. GRB 210419A: Swift-XRT refined Analysis
  32. GRB 210413B: Swift-XRT observations
  33. GRB 210411C: Swift-XRT refined Analysis
  34. GRB 210410A: Swift-XRT refined Analysis
  35. GRB 210406A: Swift-XRT observations
  36. GRB 210402A: Swift-XRT refined Analysis
  37. GRB 210323A: Swift-XRT refined Analysis
  38. GRB 210321A: Swift-XRT refined Analysis
  39. GRB 210318A: Swift-XRT refined Analysis
  40. GRB210318B: Swift detection of a burst
  41. GRB 171205A: Continued ATCA observations
  42. GRB 210305A: Swift-XRT refined Analysis
  43. GRB 210307A: Swift-XRT refined Analysis
  44. GRB 210306A: Swift-XRT refined Analysis
  45. GRB 210226A: Swift-XRT refined Analysis
  46. GRB 210218A: Swift-XRT confirmation of afterglow
  47. GRB 210222B: Swift-XRT refined Analysis
  48. GRB 210218A: Swift/UVOT observations
  49. GRB 210218A: Swift-XRT observations
  50. GRB 210217A: Swift-XRT refined Analysis
  51. GRB 210212A: Swift-XRT refined Analysis
  52. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  53. GRB 210211A: Swift-XRT refined Analysis
  54. Swift-XRT observations of IceCube-210210A
  55. GRB 210210A: Swift-XRT refined Analysis
  56. GRB 210209A: Swift-XRT refined Analysis
  57. GRB 210207B: Swift-XRT refined Analysis
  58. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  59. GRB 210205A: Swift-XRT refined Analysis
  60. Continued Chandra observations of GW170817 at ~3.3 years since merger
  61. GRB 140330A: Swift-XRT refined Analysis
  62. GRB 140320B: Swift-XRT refined Analysis
  63. GRB 140402A: Swift-XRT refined Analysis
  64. GRB 140104B: Swift-XRT refined Analysis
  65. GRB 201221D: near-infrared observation with LBT
  66. GRB 210112A: Swift-XRT refined Analysis
  67. Correction to GCN 29278: GRB 201216C XRT refined analysis
  68. GRB 201216C: Swift-XRT refined Analysis
  69. GRB 210102B: further Swift-XRT observations
  70. GW170817: HST observations at 3.4 years from merger
  71. GRB 210104A: Swift-XRT refined Analysis
  72. GRB 210104B: Swift-XRT refined Analysis
  73. GRB 210102B: Swift-XRT observations
  74. GRB 201227A: Swift-XRT observations
  75. GRB 201229A: Swift-XRT refined Analysis
  76. GRB 201223A: Swift-XRT refined Analysis
  77. Swift-XRT observations of Icecube 201222A
  78. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  79. GRB 201216A - further Swift-XRT observations
  80. GRB 201221D: Swift-XRT refined Analysis
  81. GRB 201221A: Swift-XRT refined Analysis
  82. GRB 201214A: Swift-XRT afterglow detection
  83. GRB 201216A: Swift-XRT observations
  84. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  85. GRB 201214B: Swift-XRT observations
  86. GRB 201214A: Swift-XRT observations
  87. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  88. Long-lasting X-ray emission from GW170817 detected by Chandra
  89. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  90. GRB 201208A: Swift-XRT afterglow detection
  91. GRB 201209A: Swift-XRT refined Analysis
  92. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  93. GRB 201203A: Swift-XRT afterglow detection
  94. GRB 201128B: Swift-XRT observations
  95. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  96. Swift-XRT observations of IceCube 201130A
  97. GRB 201128A: Swift-XRT refined Analysis
  98. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  99. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  100. GRB 201116A: Swift-XRT afterglow detection

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