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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"
  1. GRB 230126A: Detection by VZLUSAT-2
  2. Fermi GRB 230201A: Global MASTER-Net observations report
  3. IceCube-230201A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 221009A: radio afterglow detection with the EVN
  5. GRB 230201A: Fermi GBM Final Real-time Localization
  6. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  7. ZTF23aaarlti/AT2023avj: Assy continued optical observations
  8. ZTF23aabmzlp/AT2023azs: Mondy and AbAO optical observations
  9. AT2023avj: X-ray Detection with Swift/XRT
  10. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  11. GRB 230129A: AstroSat CZTI detection
  12. GRB 230128A: AstroSat CZTI detection
  13. GRB 230130A: Fermi GBM Final Real-time Localization
  14. ZTF23aaarlti/AT2023avj: VLA radio detection
  15. GRB 230129A: Fermi GBM Final Real-time Localization
  16. GRB 230128A: Fermi GBM Final Real-time Localization
  17. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  18. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  19. IceCube-230122A: BOOTES-2/TELMA Optical Upper Limit
  20. AT2023avj ZTF Candidate: Assy optical observations
  21. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  22. GRB 230126A: Fermi GBM Final Real-time Localization
  23. Swift-XRT observations of NuEm-230125A
  24. Trigger 1150965: Swift detection of LS V +44 17
  25. GRB 230124A: Fermi GBM Observation
  26. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230125A
  27. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  28. IceCube-230122A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 230114B: Detection by VZLUSAT-2
  30. GRB 230123A: LCOGT Optical Upper Limits
  31. Fermi GRB 230124A: Global MASTER-Net observations report
  32. GRB 230124A: Fermi GBM Final Real-time Localization
  33. GRB 230123A: Swift-BAT refined analysis
  34. GRB 230122A: Swift/BAT-GUANO detection
  35. Fermi-LAT gamma-ray observations of IceCube-230122A
  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. IceCube Alert 230122.16: Global MASTER-Net observations report
  43. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  44. GRB 230116B: Fermi GBM observation
  45. Trigger 1150107: Swift detection of LS V +44 17
  46. GRB 230120A: AstroSat CZTI detection
  47. IPN triangulation of GRB 230116B (short)
  48. GRB 230119A: CALET Gamma-Ray Burst Monitor detection
  49. GRB 230116D: 3.6m DOT optical upper limit
  50. GRB 230119A: Fermi GBM Final Real-time Localization
  51. Fermi GRB 230118A: Global MASTER-Net observations report
  52. GRB 230118A: Fermi GBM Final Real-time Localization
  53. GRB 230116D: Swift-BAT refined analysis
  54. GRB 230116C: Swift-BAT refined analysis
  55. GRB 230116D: SAO RAS further observations
  56. GRB 230116D: SAO RAS photometry
  57. GRB 230116D: KGO RC-25 optical observations
  58. GRB 230116D: Sintez-Newton/CrAO optical observations
  59. GRB 230116D: LCOGT Optical Upper Limit
  60. GRB 230116D: SAO RAS redshift
  61. Fermi trigger No 695569700: Global MASTER-Net observations report
  62. GRB 230116D: Swift-XRT refined Analysis
  63. Fermi GRB 230117A: Global MASTER-Net observations report
  64. GRB 230117A: Fermi GBM Final Real-time Localization
  65. GRB 230116D: GIT optical follow-up
  66. GRB 230116D: GIT optical follow-up
  67. GRB 230116D: Enhanced Swift-XRT position
  68. GRB 230116D: SAO RAS observations of OT brightening
  69. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  70. GRB 230116D: Nanshan/NEXT optical afterglow detection
  71. GRB 230116D: Swift detection of a burst
  72. Swift GRB230116.88: Global MASTER-Net observations report
  73. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  74. GRB 230116C: Swift detection of a burst
  75. GRB 230116B: Fermi GBM Final Real-time Localization
  76. GRB 230116A: Fermi GBM Final Real-time Localization
  77. GRB 230114A: Detection by VZLUSAT-2
  78. Fermi-LAT gamma-ray observations of IceCube-230112A
  79. GRB 230114A: Fermi GBM Final Real-time Localization
  80. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  81. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  82. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  83. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  84. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  85. GRB 230111A: Fermi GBM Observation
  86. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  87. Fermi GRB 230112A: Global MASTER-Net observations report
  88. IceCube Alert 230112.28: Global MASTER-Net observations report
  89. GRB 230112A: Fermi GBM Final Real-time Localization
  90. GRB 230111A: MAXI/GSC detection
  91. GRB 230111A: Fermi GBM Final Real-time Localization
  92. GRB 230106: AstroSat LAXPC detection
  93. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  94. Fermi trigger No 695057654: Global MASTER-Net observations report
  95. IceCube-221223A: JCMT/SCUBA2 observations
  96. GRB 230102A: Fermi GBM Observation
  97. Fermi Gamma-ray Burst Monitor trigger 694043024/221229905 is not a GRB
  98. GRB 221231A: 3.6m DOT optical upper limit
  99. GRB 230104A: AGILE/MCAL detection of a burst
  100. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV

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