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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"

7446 results found.

  1. GRB 230405B: Swift detection of a burst
  2. GRB 230307A: JWST observations consistent with the presence of a kilonova
  3. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  4. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  5. GRB 230328B: Swift detection of a burst with an optical afterglow
  6. GRB 230325A: Swift detection of a burst
  7. GRB 230322B: Swift detection of a burst with optical counterpart
  8. GRB 230314A: TURBO Optical Upper Limit
  9. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  10. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  11. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  12. GRB 230307A: Erratum of the GCN 33441
  13. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  14. GRB 230307A: optical upper limit
  15. Swift Trigger 1159108 is not a GRB
  16. GRB 230307A: Swift-XRT observations
  17. GRB 230307A: Tiled Swift observations
  18. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  19. GRB 230228A: Swift detection of a possibly short burst
  20. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  21. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  22. IceCube-230217A: BOOTES-4/MET Optical Observations
  23. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  24. GRB 230205A: Lowell Discovery Telescope Observations
  25. GRB 230216A: Swift detection of a burst
  26. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  27. Swift Trigger 1153670 is probably not a GRB
  28. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  29. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  30. GRB 230204B: Swift ToO observations
  31. GRB 230205A: Swift detection of a burst
  32. GRB 230204B: GIT discovery of the likely optical afterglow
  33. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  34. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  35. GRB 230201B: TURBO Optical Upper Limits
  36. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  37. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  38. IceCube-230201A - IceCube observation of a high-energy neutrino candidate track-like event
  39. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  40. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  41. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  42. AT2023avj ZTF Candidate: Assy optical observations
  43. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  44. GRB 230123A: Swift detection of a burst
  45. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 230116D: Swift detection of a burst
  47. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  48. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  49. GRB 221231A: 3.6m DOT optical upper limit
  50. IceCube-221223A: No Candidate Counterparts from the Zwicky Transient Facility
  51. GRB 221231A: Swift ToO observations
  52. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  53. GRB 221226B: Swift detection of a burst
  54. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  55. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  56. GRB 221218A: 3.6m DOT optical upper limit
  57. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  58. GRB 221218A: KAIT Optical Upper Limit
  59. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  60. GRB 221216A: Swift detection of a burst
  61. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  62. GRB 221215A: Swift ToO observations
  63. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  65. GRB 221206B: Swift ToO observations
  66. GRB 221202A: Swift detection of a burst
  67. GRB 221201A: Swift detection of a burst
  68. IceCube-221124A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 221120A: TURBO Optical Upper Limit
  70. GRB221120A: WIRC near-IR imaging of the afterglow candidate
  71. GRB 221120A: Liverpool Telescope Upper Limits
  72. GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
  73. GRB 221120A: LDT Optical Afterglow Candidate
  74. GRB 221120A: Swift detection of a likely short burst
  75. GRB 221110A: GRANDMA observations
  76. GRB 221110A: LCOGT Optical Afterglow Detection
  77. GRB 221110A: Swift detection of a burst with an optical counterpart
  78. IceCube-221104A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 221027B: Swift detection of a burst
  80. GRB 221024A: D50 candidate afterglow
  81. GRB 221022A: Swift ToO observations
  82. GRB 221009A: Determination of the black holes mass and spin
  83. GRB 221024A: Swift detection of a burst
  84. GRB 221022A: Swift/BAT-GUANO detection
  85. GRB 221017A: Swift ToO observations
  86. GRB 221009A: A type I BdHN of exceptional energetics
  87. GRB 221016A: Swift detection of a burst
  88. MAXI GRB 221006A: Redshifts of the possible host galaxies
  89. Afterglow limits of GRB 221006A from OHP
  90. GRB 221009A/Swift J1913.1+1946: SMA observations
  91. GRB 221006A: Swift ToO observations
  92. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  93. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  94. Swift J1913.1+1946 a new bright hard X-ray and optical transient
  95. GRB 221008A: Tiled Swift observations
  96. GRB 221006A: Tiled Swift observations
  97. GRB 220921A: ATCA detection of radio counterpart
  98. GRB 220930A: Swift detection of a burst
  99. IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event
  100. GRB 220921A: LCOGT Optical Observations

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