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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"

28054 results found.

  1. GRB 230217A: Swift-BAT refined analysis
  2. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 230220A: MAXI/GSC detection
  4. Fermi-LAT gamma-ray observations of IceCube-230217A
  5. GRB 230217A: Swift-XRT observations
  6. GRB 230216B: AstroSat CZTI detection
  7. GRB 230217A: Swift detection of a short burst
  8. GRB 230216A: Swift-BAT refined analysis
  9. GRB 230216A: Swift-XRT refined Analysis
  10. GRB 230205A: Lowell Discovery Telescope Observations
  11. GRB 230204B: Lowell Discovery Telescope Observations
  12. GRB 230216A: Enhanced Swift-XRT position
  13. GRB 230216A: AKO Upper Limit
  14. GRB 230216A: Zadko observatory - Gingin optical observations
  15. GRB 230216A: Swift detection of a burst
  16. GRB 230209B: Fermi GBM Observation
  17. IPN triangulation of GRB 230209B
  18. GRB 230204B: ATCA radio detection
  19. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  20. Swift Trigger 1153670 is probably not a GRB
  21. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  22. GRB 221009A: Continued Swift Observations
  23. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  24. GRB 230204B: MASTER early OT detection
  25. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  26. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  27. GRB 230207B: AGILE detection of a burst
  28. GRB 230204B: LCOGT Optical Upper Limits
  29. GRB 230204B: Swift/UVOT Upper Limits
  30. GRB 230205A: Swift/UVOT Upper Limits
  31. GRB 230204B: Fermi GBM detection
  32. GRB 230205A: LCOGT Optical Upper Limits
  33. GRB 230204B: Swift-XRT afterglow detection
  34. GRB 230204B: 3.6m DOT optical observation
  35. GRB 230205A: OHP/T193 optical observations
  36. GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
  37. GRB 230204A: Swift-BAT refined analysis
  38. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  39. GRB 230205A: Swift-XRT refined Analysis
  40. GRB 230205A: Enhanced Swift-XRT position
  41. GRB 230205A: Swift detection of a burst
  42. GRB 230204B: GIT discovery of the likely optical afterglow
  43. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  44. GRB 230204A: Swift/UVOT Upper Limits
  45. GRB 230204B: MAXI/GSC detection
  46. GRB 230204A: Swift-XRT refined Analysis
  47. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  48. GRB 230204A: Enhanced Swift-XRT position
  49. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  50. GRB 230201B: TURBO Optical Upper Limits
  51. IceCube-230201A: Upper limits from a search for additional neutrino events in IceCube
  52. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  53. GRB 221216A: Swift-BAT refined analysis
  54. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  55. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  56. IceCube Alert 230201.26: Global MASTER-Net observations report
  57. Fermi-LAT gamma-ray observations of IceCube-230201A
  58. GRB 230201B: Fermi GBM Final Real-time Localization
  59. GRB 230126A: Detection by VZLUSAT-2
  60. GRB 221009A: radio afterglow detection with the EVN
  61. GRB 230201A: Fermi GBM Final Real-time Localization
  62. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  63. AT2023avj: X-ray Detection with Swift/XRT
  64. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  65. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  66. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  67. Swift-XRT observations of NuEm-230125A
  68. Trigger 1150965: Swift detection of LS V +44 17
  69. GRB 230124A: Fermi GBM Observation
  70. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  71. IceCube-230122A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 230114B: Detection by VZLUSAT-2
  73. GRB 230123A: LCOGT Optical Upper Limits
  74. GRB 230123A: Swift-BAT refined analysis
  75. GRB 230122A: Swift/BAT-GUANO detection
  76. Fermi-LAT gamma-ray observations of IceCube-230122A
  77. GRB 230123A: Swift/UVOT Upper Limits
  78. GRB 230123A: Swift-XRT refined Analysis
  79. GRB 230123A: Enhanced Swift-XRT position
  80. GRB 230123A: Zadko observatory - Gingin optical observations
  81. GRB 230116C: Swift-XRT observations
  82. GRB 230123A: Swift detection of a burst
  83. Trigger 1150107: Swift detection of LS V +44 17
  84. GRB 230116D: 3.6m DOT optical upper limit
  85. GRB 230116D: Swift-BAT refined analysis
  86. GRB 230116C: Swift-BAT refined analysis
  87. GRB 230116D: SAO RAS further observations
  88. GRB 230116D: KGO RC-25 optical observations
  89. GRB 230116D: LCOGT Optical Upper Limit
  90. GRB 230116D: Swift-XRT refined Analysis
  91. GRB 230116D: GIT optical follow-up
  92. GRB 230116D: Enhanced Swift-XRT position
  93. GRB 230116D: SAO RAS observations of OT brightening
  94. GRB 230116D: Nanshan/NEXT optical afterglow detection
  95. GRB 230116D: Swift detection of a burst
  96. GRB 230114A: Detection by VZLUSAT-2
  97. Fermi-LAT gamma-ray observations of IceCube-230112A
  98. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  99. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  100. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube

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