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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"

28058 results found.

  1. GRB 230216A: Swift/UVOT Upper Limits
  2. GRB 230220A: Correction to GCN 33352
  3. GRB 230217A: Swift-XRT afterglow detection
  4. Fermi-LAT gamma-ray observations of IceCube-230220A
  5. GRB 230217A: Swift-BAT refined analysis
  6. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 230220A: MAXI/GSC detection
  8. Fermi-LAT gamma-ray observations of IceCube-230217A
  9. GRB 230217A: Swift-XRT observations
  10. GRB 230216B: AstroSat CZTI detection
  11. GRB 230217A: Swift detection of a short burst
  12. GRB 230216A: Swift-BAT refined analysis
  13. GRB 230216A: Swift-XRT refined Analysis
  14. GRB 230205A: Lowell Discovery Telescope Observations
  15. GRB 230204B: Lowell Discovery Telescope Observations
  16. GRB 230216A: Enhanced Swift-XRT position
  17. GRB 230216A: AKO Upper Limit
  18. GRB 230216A: Zadko observatory - Gingin optical observations
  19. GRB 230216A: Swift detection of a burst
  20. GRB 230209B: Fermi GBM Observation
  21. IPN triangulation of GRB 230209B
  22. GRB 230204B: ATCA radio detection
  23. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  24. Swift Trigger 1153670 is probably not a GRB
  25. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  26. GRB 221009A: Continued Swift Observations
  27. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  28. GRB 230204B: MASTER early OT detection
  29. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  30. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  31. GRB 230207B: AGILE detection of a burst
  32. GRB 230204B: LCOGT Optical Upper Limits
  33. GRB 230204B: Swift/UVOT Upper Limits
  34. GRB 230205A: Swift/UVOT Upper Limits
  35. GRB 230204B: Fermi GBM detection
  36. GRB 230205A: LCOGT Optical Upper Limits
  37. GRB 230204B: Swift-XRT afterglow detection
  38. GRB 230204B: 3.6m DOT optical observation
  39. GRB 230205A: OHP/T193 optical observations
  40. GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
  41. GRB 230204A: Swift-BAT refined analysis
  42. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  43. GRB 230205A: Swift-XRT refined Analysis
  44. GRB 230205A: Enhanced Swift-XRT position
  45. GRB 230205A: Swift detection of a burst
  46. GRB 230204B: GIT discovery of the likely optical afterglow
  47. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  48. GRB 230204A: Swift/UVOT Upper Limits
  49. GRB 230204B: MAXI/GSC detection
  50. GRB 230204A: Swift-XRT refined Analysis
  51. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  52. GRB 230204A: Enhanced Swift-XRT position
  53. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  54. GRB 230201B: TURBO Optical Upper Limits
  55. IceCube-230201A: Upper limits from a search for additional neutrino events in IceCube
  56. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  57. GRB 221216A: Swift-BAT refined analysis
  58. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  59. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  60. IceCube Alert 230201.26: Global MASTER-Net observations report
  61. Fermi-LAT gamma-ray observations of IceCube-230201A
  62. GRB 230201B: Fermi GBM Final Real-time Localization
  63. GRB 230126A: Detection by VZLUSAT-2
  64. GRB 221009A: radio afterglow detection with the EVN
  65. GRB 230201A: Fermi GBM Final Real-time Localization
  66. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  67. AT2023avj: X-ray Detection with Swift/XRT
  68. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  69. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  70. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  71. Swift-XRT observations of NuEm-230125A
  72. Trigger 1150965: Swift detection of LS V +44 17
  73. GRB 230124A: Fermi GBM Observation
  74. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  75. IceCube-230122A: Upper limits from a search for additional neutrino events in IceCube
  76. GRB 230114B: Detection by VZLUSAT-2
  77. GRB 230123A: LCOGT Optical Upper Limits
  78. GRB 230123A: Swift-BAT refined analysis
  79. GRB 230122A: Swift/BAT-GUANO detection
  80. Fermi-LAT gamma-ray observations of IceCube-230122A
  81. GRB 230123A: Swift/UVOT Upper Limits
  82. GRB 230123A: Swift-XRT refined Analysis
  83. GRB 230123A: Enhanced Swift-XRT position
  84. GRB 230123A: Zadko observatory - Gingin optical observations
  85. GRB 230116C: Swift-XRT observations
  86. GRB 230123A: Swift detection of a burst
  87. Trigger 1150107: Swift detection of LS V +44 17
  88. GRB 230116D: 3.6m DOT optical upper limit
  89. GRB 230116D: Swift-BAT refined analysis
  90. GRB 230116C: Swift-BAT refined analysis
  91. GRB 230116D: SAO RAS further observations
  92. GRB 230116D: KGO RC-25 optical observations
  93. GRB 230116D: LCOGT Optical Upper Limit
  94. GRB 230116D: Swift-XRT refined Analysis
  95. GRB 230116D: GIT optical follow-up
  96. GRB 230116D: Enhanced Swift-XRT position
  97. GRB 230116D: SAO RAS observations of OT brightening
  98. GRB 230116D: Nanshan/NEXT optical afterglow detection
  99. GRB 230116D: Swift detection of a burst
  100. GRB 230114A: Detection by VZLUSAT-2

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