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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"

26042 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. ZTF23aabmzlp/AT2023azs: VLA radio detection
  18. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  19. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  20. GRB 221009A: radio afterglow detection with the EVN
  21. ZTF23aaarlti/AT2023avj: Assy continued optical observations
  22. AT2023avj: X-ray Detection with Swift/XRT
  23. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  24. ZTF23aaarlti/AT2023avj: VLA radio detection
  25. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  26. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  27. AT2023avj ZTF Candidate: Assy optical observations
  28. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  29. Swift-XRT observations of NuEm-230125A
  30. Trigger 1150965: Swift detection of LS V +44 17
  31. GRB 230124A: Fermi GBM Observation
  32. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  33. GRB 230123A: LCOGT Optical Upper Limits
  34. GRB 230123A: Swift-BAT refined analysis
  35. GRB 230122A: Swift/BAT-GUANO detection
  36. GRB 230123A: Swift/UVOT Upper Limits
  37. GRB 230123A: Swift-XRT refined Analysis
  38. GRB 230123A: Enhanced Swift-XRT position
  39. GRB 230123A: Zadko observatory - Gingin optical observations
  40. GRB 230116C: Swift-XRT observations
  41. GRB 230123A: Swift detection of a burst
  42. Trigger 1150107: Swift detection of LS V +44 17
  43. GRB 230116D: 3.6m DOT optical upper limit
  44. GRB 230116D: Swift-BAT refined analysis
  45. GRB 230116C: Swift-BAT refined analysis
  46. GRB 230116D: SAO RAS further observations
  47. GRB 230116D: SAO RAS photometry
  48. GRB 230116D: KGO RC-25 optical observations
  49. GRB 230116D: Sintez-Newton/CrAO optical observations
  50. GRB 230116D: LCOGT Optical Upper Limit
  51. GRB 230116D: SAO RAS redshift
  52. GRB 230116D: Swift-XRT refined Analysis
  53. GRB 230116D: GIT optical follow-up
  54. GRB 230116D: Enhanced Swift-XRT position
  55. GRB 230116D: SAO RAS observations of OT brightening
  56. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  57. GRB 230116D: Nanshan/NEXT optical afterglow detection
  58. GRB 230116D: Swift detection of a burst
  59. Swift GRB230116.88: Global MASTER-Net observations report
  60. GRB 230116C: Swift detection of a burst
  61. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  62. GRB 230102A: Fermi GBM Observation
  63. GRB 221231A: 3.6m DOT optical upper limit
  64. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  65. GRB 221231A: Fermi GBM Observation
  66. GRB 221231A: Swift-XRT afterglow detection
  67. GRB 221231A: AKO Upper Limit
  68. GRB 221231A: Swift-XRT observations
  69. GRB 221231A: Swift ToO observations
  70. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  71. GRB 221226A: Fermi GBM detection
  72. IPN triangulation of GRB 221226A
  73. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  74. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  75. GRB 221226B: LCOGT Optical Upper Limits
  76. GRB 221226B Swift-BAT refined analysis
  77. GRB 221226B: Swift-UVOT Detection
  78. GRB 221226B: Fermi GBM Observation
  79. GRB 221226B: Swift-XRT refined Analysis
  80. GRB 221226B: VLT/X-shooter redshift and host galaxy
  81. GRB 221226B: Enhanced Swift-XRT position
  82. GRB 221226B: Swift detection of a burst
  83. Swift GRB221226.95: Global MASTER-Net observations report
  84. GRB 221218A: 3.6m DOT optical upper limit
  85. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  86. GRB 221218A: KAIT Optical Upper Limit
  87. GRB 221215A: Fermi GBM Detection
  88. GRB 221216A: Swift/UVOT Upper Limits
  89. GRB 221216A: Fermi GBM observation
  90. GRB 221216A: Swift-XRT refined Analysis
  91. GRB 221216A: AKO Upper Limit
  92. GRB 221215A: Swift-XRT observations
  93. GRB 221216A: Enhanced Swift-XRT position
  94. Swift GRB 221216A: Global MASTER-Net observations report
  95. GRB 221216A: Zadko observatory - Gingin optical observations
  96. GRB 221216A: Nanshan/NEXT optical upper limits
  97. GRB 221216A: Swift detection of a burst
  98. GRB 221215A: Swift ToO observations
  99. GRB 221215A: Swift/BAT-GUANO arcminute localization
  100. Swift GRB221215.15: Global MASTER-Net observations report

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