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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"

21458 results found.

  1. GRB 230205A: Swift-XRT refined Analysis
  2. GRB 230204B: Swift ToO observations
  3. GRB 230205A: Enhanced Swift-XRT position
  4. GRB 230205A: BOOTES-5/JGT early optical upper limit
  5. GRB 230204B: Detection by GRBAlpha
  6. GRB 230204B: AGILE detection
  7. GRB 230205A: Swift detection of a burst
  8. GRB 230204B: GIT discovery of the likely optical afterglow
  9. GRB 230204B: AstroSat CZTI detection
  10. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  11. GRB 230204A: Swift/UVOT Upper Limits
  12. GRB 230204A: Swift-XRT refined Analysis
  13. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  14. GRB 230204A: Enhanced Swift-XRT position
  15. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  16. GRB 221216A: Swift-BAT refined analysis
  17. AT2023avj: X-ray Detection with Swift/XRT
  18. Swift-XRT observations of NuEm-230125A
  19. Trigger 1150965: Swift detection of LS V +44 17
  20. GRB 230124A: Fermi GBM Observation
  21. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  22. GRB 230123A: LCOGT Optical Upper Limits
  23. GRB 230123A: Swift-BAT refined analysis
  24. GRB 230122A: Swift/BAT-GUANO detection
  25. GRB 230123A: Swift/UVOT Upper Limits
  26. GRB 230123A: Swift-XRT refined Analysis
  27. GRB 230123A: Enhanced Swift-XRT position
  28. GRB 230123A: Zadko observatory - Gingin optical observations
  29. GRB 230116C: Swift-XRT observations
  30. GRB 230123A: Swift detection of a burst
  31. Trigger 1150107: Swift detection of LS V +44 17
  32. GRB 230116D: 3.6m DOT optical upper limit
  33. GRB 230116D: Swift-BAT refined analysis
  34. GRB 230116C: Swift-BAT refined analysis
  35. GRB 230116D: SAO RAS photometry
  36. GRB 230116D: LCOGT Optical Upper Limit
  37. GRB 230116D: Swift-XRT refined Analysis
  38. GRB 230116D: GIT optical follow-up
  39. GRB 230116D: Enhanced Swift-XRT position
  40. GRB 230116D: SAO RAS observations of OT brightening
  41. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  42. GRB 230116D: Nanshan/NEXT optical afterglow detection
  43. GRB 230116D: Swift detection of a burst
  44. Swift GRB230116.88: Global MASTER-Net observations report
  45. GRB 230116C: Swift detection of a burst
  46. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  47. GRB 230102A: Fermi GBM Observation
  48. GRB 221231A: 3.6m DOT optical upper limit
  49. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  50. GRB 221231A: Fermi GBM Observation
  51. GRB 221231A: Swift-XRT afterglow detection
  52. GRB 221231A: AKO Upper Limit
  53. GRB 221231A: Swift-XRT observations
  54. GRB 221231A: Swift ToO observations
  55. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  56. GRB 221226A: Fermi GBM detection
  57. IPN triangulation of GRB 221226A
  58. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  59. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  60. GRB 221226B: LCOGT Optical Upper Limits
  61. GRB 221226B Swift-BAT refined analysis
  62. GRB 221226B: Swift-UVOT Detection
  63. GRB 221226B: Fermi GBM Observation
  64. GRB 221226B: Swift-XRT refined Analysis
  65. GRB 221226B: VLT/X-shooter redshift and host galaxy
  66. GRB 221226B: Enhanced Swift-XRT position
  67. GRB 221226B: Swift detection of a burst
  68. Swift GRB221226.95: Global MASTER-Net observations report
  69. GRB 221215A: Fermi GBM Detection
  70. GRB 221216A: Swift/UVOT Upper Limits
  71. GRB 221216A: Fermi GBM observation
  72. GRB 221216A: Swift-XRT refined Analysis
  73. GRB 221216A: AKO Upper Limit
  74. GRB 221215A: Swift-XRT observations
  75. GRB 221216A: Enhanced Swift-XRT position
  76. Swift GRB 221216A: Global MASTER-Net observations report
  77. GRB 221216A: Zadko observatory - Gingin optical observations
  78. GRB 221216A: Nanshan/NEXT optical upper limits
  79. GRB 221216A: Swift detection of a burst
  80. GRB 221215A: Swift ToO observations
  81. GRB 221215A: Swift/BAT-GUANO arcminute localization
  82. Swift GRB221215.15: Global MASTER-Net observations report
  83. Swift Trigger 1144538 is not a GRB
  84. GRB 221009A: MuSCAT3 observations
  85. GRB 221206B: Fermi GBM observation
  86. GRB 221206B: Swift-XRT observations
  87. GRB 221206B: Detection by GRBAlpha
  88. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  89. GRB 221206B: Swift ToO observations
  90. Swift/BAT trigger #1143281 is not a GRB
  91. Swift GRB221204.45 AKO Upper Limit
  92. Swift GRB221204.45: Global MASTER-Net observations report
  93. GRB 221202A: Swift/UVOT Detection
  94. GRB 221202A: Swift-BAT refined analysis
  95. GRB 221202A: VLT/FORS2 Afterglow Discovery
  96. GRB 221201A: Swift-BAT refined analysis
  97. GRB 221201A: Fermi GBM observation
  98. GRB 221202A: Swift-XRT refined Analysis
  99. GRB 221202A: LCOGT Optical Upper Limits
  100. GRB 221202A: Enhanced Swift-XRT position

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