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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 231110A: GECAM-B detection (correction)
  2. GRB 231111A: Enhanced Swift-XRT position
  3. GRB 231111A: GECAM-C detection of a long burst
  4. GRB 231110A: GECAM detection
  5. GRB 231110A: GOTO optical upper limits
  6. GRB 231110A: SAO RAS optical observations
  7. GRB 231110A: Swift-XRT afterglow detection
  8. GRB231111A: YAHPT Observations
  9. GRB231111A: GIT confirmation of the optical afterglow
  10. GRB 231111A: MASTER OT earlier detection
  11. GRB 231111A: Nanshan/HMT optical observations
  12. GRB 231111A: Swift detection of a burst with an optical counterpart
  13. Swift GRB231111.60: Global MASTER-Net observations report
  14. GRB231110A: WFST Observation and upper limits
  15. Swift GRB231110.89: Global MASTER-Net observations report
  16. GRB 231110A: Swift detection of a burst
  17. LIGO/Virgo/KAGRA S231110g: Updated Sky localization
  18. LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
  19. GRB 231109A: Fermi GBM Final Localization
  20. IceCube-231103A: No candidates from the Zwicky Transient Facility
  21. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  22. Fermi trigger No 721204446: Global MASTER-Net observations report
  23. Fermi GRB 231108A: Global MASTER-Net observations report
  24. GRB 231108A: Fermi GBM Final Real-time Localization
  25. LIGO/Virgo/KAGRA O4 Landscape
  26. LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
  27. GRB 231106A: AstroSat CZTI detection
  28. GRB 231106A: CALET Gamma-Ray Burst Monitor detection
  29. GRB 231104A: Swift-BAT refined analysis
  30. Fermi trigger No 721006392: Global MASTER-Net observations report
  31. Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
  32. GRB 231104A: FRAM-ORM optical limit
  33. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  34. Fermi GRB 231106A: Global MASTER-Net observations report
  35. GRB 231104A: Wendelstein Optical/Infrared Observations
  36. GRB 231104A: NuSTAR Observation of the prompt emission
  37. GRB 231106A: Fermi GBM Final Real-time Localization
  38. GRB 231104A: 3.6m DOT optical upper limit
  39. IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
  40. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  41. Fermi-LAT gamma-ray observations of IceCube-231103A
  42. GRB 231104A: NOT upper limit
  43. GRB 231104A: Fermi GBM Observation
  44. GRB 231104B: Fermi GBM Final Real-time Localization
  45. Fermi GRB 231103A: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  47. GRB 231104A: AKO Upper Limit
  48. GRB 231104A: AstroSat CZTI detection
  49. GRB 231104A: Swift-XRT refined Analysis
  50. GRB 231104A: Fermi-LAT detection
  51. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  52. GRB 231104A: Swift/UVOT Upper Limits
  53. GRB 231104A: Enhanced Swift-XRT position
  54. GRB231104A: LCOGT Optical Upper Limits
  55. GRB 231104A: Swift detection of a bright burst
  56. GRB 231104A: Fermi GBM Final Real-time Localization
  57. Swift GRB231104.07: Global MASTER-Net observations report
  58. IceCube Alert 231103.39: Global MASTER-Net observations report
  59. GRB 231103A: Fermi GBM Final Real-time Localization
  60. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  61. Fermi-LAT gamma-ray observations of IceCube-231027A
  62. LIGO/Virgo/KAGRA S231102w: Updated Sky localization
  63. LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
  64. GRB 231101A: Glowbug gamma-ray detection
  65. GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
  66. LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
  67. New Swift-BAT/GUANO and IceCube Notices Available via GCN Kafka
  68. Fermi trigger No 720498201: Global MASTER-Net observations report
  69. GRB 231101A: Fermi GBM Final Real-time Localization
  70. GRB 231030B: GRBAlpha detection
  71. GRB 231028B: VZLUSAT-2 detection
  72. Fermi trigger No 720415645: Global MASTER-Net observations report
  73. GRB 231030B: Fermi GBM Detection
  74. GRB 231030B: AstroSat CZTI detection
  75. Fermi GRB 231030B: Global MASTER-Net observations report
  76. IPN triangulation of GRB 231020A
  77. GRB 231030B: BALROG localization (Fermi Trigger 720388704 / GRB 231030832)
  78. GRB 231030B: Fermi GBM Final Real-time Localization
  79. GRB 231028A: Swift-BAT refined analysis
  80. IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
  81. LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
  82. LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
  83. GRB 231024A: AKO Optical Counterpart Candidate
  84. GRB 231028A: CALET Gamma-Ray Burst Monitor detection
  85. Fermi GRB 231030A: Global MASTER-Net observations report
  86. GRB 231030A: Fermi GBM Final Real-time Localization
  87. LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
  88. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  90. GRID detection of GRB 231020A
  91. LIGO/Virgo/KAGRA S231029k: Global MASTER-Net observations report
  92. GRB 231028A: AstroSat CZTI detection
  93. GRB 231028A: Glowbug gamma-ray detection
  94. GRB 231028A: Fermi GBM Detection
  95. Fermi trigger No 720224759: Global MASTER-Net observations report
  96. Swift GRB 231028A: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
  98. LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
  99. GRB 231028A: Swift detection of a burst
  100. GRB 231028A: Fermi GBM Final Real-time Localization

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