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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"

27774 results found.

  1. GRB 230209B: Fermi GBM Observation
  2. IPN triangulation of GRB 230209B
  3. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  4. GRB 230204B: ATCA radio detection
  5. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  6. GRB 230211A: Fermi GBM Final Real-time Localization
  7. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  8. Swift Trigger 1153670 is probably not a GRB
  9. GRB 230210A: Fermi GBM Final Real-time Localization
  10. GRB 230209B: Fermi GBM Final Real-time Localization
  11. GRB 230209A: Fermi GBM Final Real-time Localization
  12. GRB 221009A: Continued Swift Observations
  13. GRB 230207B: Detection by GRBAlpha
  14. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  15. GRB 230204B: MASTER early OT detection
  16. GRB 230208A: Fermi GBM Final Real-time Localization
  17. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  18. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  19. GRB 230207B: AGILE detection of a burst
  20. GRB 230207A: Fermi GBM Final Real-time Localization
  21. GRB 230204B: Swift/UVOT Upper Limits
  22. GRB 230205A: Swift/UVOT Upper Limits
  23. GRB 230204B: Fermi GBM detection
  24. GRB 230204B: Swift-XRT afterglow detection
  25. GRB 230204B: 3.6m DOT optical observation
  26. GRB 230205A: SVOM/C-GFT optical upper limit
  27. GRB 230204B: VLT/X-shooter redshift
  28. GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
  29. GRB 230204A: Swift-BAT refined analysis
  30. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  31. GRB 230205A: Swift-XRT refined Analysis
  32. GRB 230204B: Swift ToO observations
  33. GRB 230205A: Enhanced Swift-XRT position
  34. GRB 230205A: BOOTES-5/JGT early optical upper limit
  35. GRB 230204B: Detection by GRBAlpha
  36. GRB 230204B: AGILE detection
  37. GRB 230205A: Swift detection of a burst
  38. GRB 230204B: GIT discovery of the likely optical afterglow
  39. GRB 230204B: AstroSat CZTI detection
  40. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  41. GRB 230204A: Swift/UVOT Upper Limits
  42. GRB 230204B: MAXI/GSC detection
  43. GRB 230204A: Swift-XRT refined Analysis
  44. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  45. GRB 230204A: Enhanced Swift-XRT position
  46. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  47. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  48. GRB 221216A: Swift-BAT refined analysis
  49. ZTF23aabmzlp/AT2023azs: VLA radio detection
  50. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  51. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  52. GRB 230201B: Fermi GBM Final Real-time Localization
  53. GRB 230126A: Detection by VZLUSAT-2
  54. IceCube-230201A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 221009A: radio afterglow detection with the EVN
  56. GRB 230201A: Fermi GBM Final Real-time Localization
  57. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  58. AT2023avj: X-ray Detection with Swift/XRT
  59. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  60. GRB 230129A: AstroSat CZTI detection
  61. GRB 230128A: AstroSat CZTI detection
  62. GRB 230130A: Fermi GBM Final Real-time Localization
  63. ZTF23aaarlti/AT2023avj: VLA radio detection
  64. GRB 230129A: Fermi GBM Final Real-time Localization
  65. GRB 230128A: Fermi GBM Final Real-time Localization
  66. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  67. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  68. GRB 230126A: Fermi GBM Final Real-time Localization
  69. Swift-XRT observations of NuEm-230125A
  70. Trigger 1150965: Swift detection of LS V +44 17
  71. GRB 230124A: Fermi GBM Observation
  72. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  73. GRB 230114B: Detection by VZLUSAT-2
  74. GRB 230124A: Fermi GBM Final Real-time Localization
  75. GRB 230123A: Swift-BAT refined analysis
  76. GRB 230122A: Swift/BAT-GUANO detection
  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. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  84. Trigger 1150107: Swift detection of LS V +44 17
  85. GRB 230120A: AstroSat CZTI detection
  86. IPN triangulation of GRB 230116B (short)
  87. GRB 230119A: CALET Gamma-Ray Burst Monitor detection
  88. GRB 230116D: 3.6m DOT optical upper limit
  89. GRB 230119A: Fermi GBM Final Real-time Localization
  90. GRB 230118A: Fermi GBM Final Real-time Localization
  91. GRB 230116D: Swift-BAT refined analysis
  92. GRB 230116C: Swift-BAT refined analysis
  93. GRB 230116D: Swift-XRT refined Analysis
  94. GRB 230117A: Fermi GBM Final Real-time Localization
  95. GRB 230116D: GIT optical follow-up
  96. GRB 230116D: Enhanced Swift-XRT position
  97. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  98. GRB 230116D: Nanshan/NEXT optical afterglow detection
  99. GRB 230116D: Swift detection of a burst
  100. Swift GRB230116.88: Global MASTER-Net observations report

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