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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 231106B: GRBAlpha detection
  2. GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  3. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  4. GRB 231111A: Swift-XRT refined Analysis
  5. GRB 231111A: Mondy optical observations
  6. GRB 231111A: GECAM-C detection of a long burst (correction)
  7. GRB 231110A: GECAM-B detection (correction)
  8. GRB 231111A: Enhanced Swift-XRT position
  9. GRB 231111A: GECAM-C detection of a long burst
  10. GRB 231110A: GECAM detection
  11. GRB 231110A: GOTO optical upper limits
  12. GRB 231110A: SAO RAS optical observations
  13. GRB 231110A: Swift-XRT afterglow detection
  14. GRB231111A: YAHPT Observations
  15. GRB231111A: GIT confirmation of the optical afterglow
  16. GRB 231111A: MASTER OT earlier detection
  17. GRB 231111A: Nanshan/HMT optical observations
  18. GRB 231111A: Swift detection of a burst with an optical counterpart
  19. Swift GRB231111.60: Global MASTER-Net observations report
  20. GRB231110A: WFST Observation and upper limits
  21. Swift GRB231110.89: Global MASTER-Net observations report
  22. GRB 231110A: Swift detection of a burst
  23. LIGO/Virgo/KAGRA S231110g: Updated Sky localization
  24. LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
  25. GRB 231109A: Fermi GBM Final Localization
  26. IceCube-231103A: No candidates from the Zwicky Transient Facility
  27. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  28. Fermi trigger No 721204446: Global MASTER-Net observations report
  29. Fermi GRB 231108A: Global MASTER-Net observations report
  30. GRB 231108A: Fermi GBM Final Real-time Localization
  31. LIGO/Virgo/KAGRA O4 Landscape
  32. LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
  33. GRB 231106A: AstroSat CZTI detection
  34. GRB 231106A: CALET Gamma-Ray Burst Monitor detection
  35. GRB 231104A: Swift-BAT refined analysis
  36. Fermi trigger No 721006392: Global MASTER-Net observations report
  37. Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
  38. GRB 231104A: FRAM-ORM optical limit
  39. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  40. Fermi GRB 231106A: Global MASTER-Net observations report
  41. GRB 231104A: Wendelstein Optical/Infrared Observations
  42. GRB 231104A: NuSTAR Observation of the prompt emission
  43. GRB 231106A: Fermi GBM Final Real-time Localization
  44. GRB 231104A: 3.6m DOT optical upper limit
  45. IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
  46. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  47. Fermi-LAT gamma-ray observations of IceCube-231103A
  48. GRB 231104A: NOT upper limit
  49. GRB 231104A: Fermi GBM Observation
  50. GRB 231104B: Fermi GBM Final Real-time Localization
  51. Fermi GRB 231103A: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  53. GRB 231104A: AKO Upper Limit
  54. GRB 231104A: AstroSat CZTI detection
  55. GRB 231104A: Swift-XRT refined Analysis
  56. GRB 231104A: Fermi-LAT detection
  57. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  58. GRB 231104A: Swift/UVOT Upper Limits
  59. GRB 231104A: Enhanced Swift-XRT position
  60. GRB231104A: LCOGT Optical Upper Limits
  61. GRB 231104A: Swift detection of a bright burst
  62. GRB 231104A: Fermi GBM Final Real-time Localization
  63. Swift GRB231104.07: Global MASTER-Net observations report
  64. IceCube Alert 231103.39: Global MASTER-Net observations report
  65. GRB 231103A: Fermi GBM Final Real-time Localization
  66. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  67. Fermi-LAT gamma-ray observations of IceCube-231027A
  68. LIGO/Virgo/KAGRA S231102w: Updated Sky localization
  69. LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
  70. GRB 231101A: Glowbug gamma-ray detection
  71. GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
  72. LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
  73. New Swift-BAT/GUANO and IceCube Notices Available via GCN Kafka
  74. Fermi trigger No 720498201: Global MASTER-Net observations report
  75. GRB 231101A: Fermi GBM Final Real-time Localization
  76. GRB 231030B: GRBAlpha detection
  77. GRB 231028B: VZLUSAT-2 detection
  78. Fermi trigger No 720415645: Global MASTER-Net observations report
  79. GRB 231030B: Fermi GBM Detection
  80. GRB 231030B: AstroSat CZTI detection
  81. Fermi GRB 231030B: Global MASTER-Net observations report
  82. IPN triangulation of GRB 231020A
  83. GRB 231030B: BALROG localization (Fermi Trigger 720388704 / GRB 231030832)
  84. GRB 231030B: Fermi GBM Final Real-time Localization
  85. GRB 231028A: Swift-BAT refined analysis
  86. IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
  87. LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
  89. GRB 231024A: AKO Optical Counterpart Candidate
  90. GRB 231028A: CALET Gamma-Ray Burst Monitor detection
  91. Fermi GRB 231030A: Global MASTER-Net observations report
  92. GRB 231030A: Fermi GBM Final Real-time Localization
  93. LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
  94. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  95. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  96. GRID detection of GRB 231020A
  97. LIGO/Virgo/KAGRA S231029k: Global MASTER-Net observations report
  98. GRB 231028A: AstroSat CZTI detection
  99. GRB 231028A: Glowbug gamma-ray detection
  100. GRB 231028A: Fermi GBM Detection

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