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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. IceCube-230201A: Upper limits from a search for additional neutrino events in IceCube
  2. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  3. GRB 221216A: Swift-BAT refined analysis
  4. ZTF23aabmzlp/AT2023azs: VLA radio detection
  5. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  6. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  7. IceCube Alert 230201.26: Global MASTER-Net observations report
  8. Fermi GRB 230201B: Global MASTER-Net observations report
  9. Fermi-LAT gamma-ray observations of IceCube-230201A
  10. GRB 230201B: Fermi GBM Final Real-time Localization
  11. GRB 230126A: Detection by VZLUSAT-2
  12. Fermi GRB 230201A: Global MASTER-Net observations report
  13. IceCube-230201A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 221009A: radio afterglow detection with the EVN
  15. GRB 230201A: Fermi GBM Final Real-time Localization
  16. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  17. ZTF23aaarlti/AT2023avj: Assy continued optical observations
  18. ZTF23aabmzlp/AT2023azs: Mondy and AbAO optical observations
  19. AT2023avj: X-ray Detection with Swift/XRT
  20. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  21. GRB 230129A: AstroSat CZTI detection
  22. GRB 230128A: AstroSat CZTI detection
  23. GRB 230130A: Fermi GBM Final Real-time Localization
  24. ZTF23aaarlti/AT2023avj: VLA radio detection
  25. GRB 230129A: Fermi GBM Final Real-time Localization
  26. GRB 230128A: Fermi GBM Final Real-time Localization
  27. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  28. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  29. IceCube-230122A: BOOTES-2/TELMA Optical Upper Limit
  30. AT2023avj ZTF Candidate: Assy optical observations
  31. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  32. GRB 230126A: Fermi GBM Final Real-time Localization
  33. Swift-XRT observations of NuEm-230125A
  34. Trigger 1150965: Swift detection of LS V +44 17
  35. GRB 230124A: Fermi GBM Observation
  36. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230125A
  37. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  38. IceCube-230122A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 230114B: Detection by VZLUSAT-2
  40. GRB 230123A: LCOGT Optical Upper Limits
  41. Fermi GRB 230124A: Global MASTER-Net observations report
  42. GRB 230124A: Fermi GBM Final Real-time Localization
  43. GRB 230123A: Swift-BAT refined analysis
  44. GRB 230122A: Swift/BAT-GUANO detection
  45. Fermi-LAT gamma-ray observations of IceCube-230122A
  46. GRB 230123A: Swift/UVOT Upper Limits
  47. GRB 230123A: Swift-XRT refined Analysis
  48. GRB 230123A: Enhanced Swift-XRT position
  49. GRB 230123A: Zadko observatory - Gingin optical observations
  50. GRB 230116C: Swift-XRT observations
  51. GRB 230123A: Swift detection of a burst
  52. IceCube Alert 230122.16: Global MASTER-Net observations report
  53. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  54. GRB 230116B: Fermi GBM observation
  55. Trigger 1150107: Swift detection of LS V +44 17
  56. GRB 230120A: AstroSat CZTI detection
  57. IPN triangulation of GRB 230116B (short)
  58. GRB 230119A: CALET Gamma-Ray Burst Monitor detection
  59. GRB 230116D: 3.6m DOT optical upper limit
  60. GRB 230119A: Fermi GBM Final Real-time Localization
  61. Fermi GRB 230118A: Global MASTER-Net observations report
  62. GRB 230118A: Fermi GBM Final Real-time Localization
  63. GRB 230116D: Swift-BAT refined analysis
  64. GRB 230116C: Swift-BAT refined analysis
  65. GRB 230116D: SAO RAS further observations
  66. GRB 230116D: SAO RAS photometry
  67. GRB 230116D: KGO RC-25 optical observations
  68. GRB 230116D: Sintez-Newton/CrAO optical observations
  69. GRB 230116D: LCOGT Optical Upper Limit
  70. GRB 230116D: SAO RAS redshift
  71. Fermi trigger No 695569700: Global MASTER-Net observations report
  72. GRB 230116D: Swift-XRT refined Analysis
  73. Fermi GRB 230117A: Global MASTER-Net observations report
  74. GRB 230117A: Fermi GBM Final Real-time Localization
  75. GRB 230116D: GIT optical follow-up
  76. GRB 230116D: GIT optical follow-up
  77. GRB 230116D: Enhanced Swift-XRT position
  78. GRB 230116D: SAO RAS observations of OT brightening
  79. GRB 230116D: Sintez-Newton/CrAO optical afterglow detection
  80. GRB 230116D: Nanshan/NEXT optical afterglow detection
  81. GRB 230116D: Swift detection of a burst
  82. Swift GRB230116.88: Global MASTER-Net observations report
  83. IceCube-230112A: No Candidate Counterparts from the Zwicky Transient Facility
  84. GRB 230116C: Swift detection of a burst
  85. GRB 230116B: Fermi GBM Final Real-time Localization
  86. GRB 230116A: Fermi GBM Final Real-time Localization
  87. GRB 230114A: Detection by VZLUSAT-2
  88. Fermi-LAT gamma-ray observations of IceCube-230112A
  89. GRB 230114A: Fermi GBM Final Real-time Localization
  90. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  91. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  92. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-230112A: BOOTES-4/MET Optical Upper Limit
  94. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  95. GRB 230111A: Fermi GBM Observation
  96. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  97. Fermi GRB 230112A: Global MASTER-Net observations report
  98. IceCube Alert 230112.28: Global MASTER-Net observations report
  99. GRB 230112A: Fermi GBM Final Real-time Localization
  100. GRB 230111A: MAXI/GSC detection

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