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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 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  2. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  3. GRB 231111A: Swift-XRT refined Analysis
  4. GRB 231111A: Mondy optical observations
  5. GRB 231111A: GECAM-C detection of a long burst (correction)
  6. GRB 231110A: GECAM-B detection (correction)
  7. GRB 231111A: Enhanced Swift-XRT position
  8. GRB 231111A: GECAM-C detection of a long burst
  9. GRB 231110A: GECAM detection
  10. GRB 231110A: GOTO optical upper limits
  11. GRB 231110A: SAO RAS optical observations
  12. GRB 231110A: Swift-XRT afterglow detection
  13. GRB231111A: YAHPT Observations
  14. GRB231111A: GIT confirmation of the optical afterglow
  15. GRB 231111A: MASTER OT earlier detection
  16. GRB 231111A: Nanshan/HMT optical observations
  17. GRB 231111A: Swift detection of a burst with an optical counterpart
  18. Swift GRB231111.60: Global MASTER-Net observations report
  19. GRB231110A: WFST Observation and upper limits
  20. Swift GRB231110.89: Global MASTER-Net observations report
  21. GRB 231110A: Swift detection of a burst
  22. LIGO/Virgo/KAGRA S231110g: Updated Sky localization
  23. LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
  24. GRB 231109A: Fermi GBM Final Localization
  25. IceCube-231103A: No candidates from the Zwicky Transient Facility
  26. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  27. Fermi trigger No 721204446: Global MASTER-Net observations report
  28. Fermi GRB 231108A: Global MASTER-Net observations report
  29. GRB 231108A: Fermi GBM Final Real-time Localization
  30. LIGO/Virgo/KAGRA O4 Landscape
  31. LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
  32. GRB 231106A: AstroSat CZTI detection
  33. GRB 231106A: CALET Gamma-Ray Burst Monitor detection
  34. GRB 231104A: Swift-BAT refined analysis
  35. Fermi trigger No 721006392: Global MASTER-Net observations report
  36. Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
  37. GRB 231104A: FRAM-ORM optical limit
  38. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  39. Fermi GRB 231106A: Global MASTER-Net observations report
  40. GRB 231104A: Wendelstein Optical/Infrared Observations
  41. GRB 231104A: NuSTAR Observation of the prompt emission
  42. GRB 231106A: Fermi GBM Final Real-time Localization
  43. GRB 231104A: 3.6m DOT optical upper limit
  44. IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
  45. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  46. Fermi-LAT gamma-ray observations of IceCube-231103A
  47. GRB 231104A: NOT upper limit
  48. GRB 231104A: Fermi GBM Observation
  49. GRB 231104B: Fermi GBM Final Real-time Localization
  50. Fermi GRB 231103A: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  52. GRB 231104A: AKO Upper Limit
  53. GRB 231104A: AstroSat CZTI detection
  54. GRB 231104A: Swift-XRT refined Analysis
  55. GRB 231104A: Fermi-LAT detection
  56. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  57. GRB 231104A: Swift/UVOT Upper Limits
  58. GRB 231104A: Enhanced Swift-XRT position
  59. GRB231104A: LCOGT Optical Upper Limits
  60. GRB 231104A: Swift detection of a bright burst
  61. GRB 231104A: Fermi GBM Final Real-time Localization
  62. Swift GRB231104.07: Global MASTER-Net observations report
  63. IceCube Alert 231103.39: Global MASTER-Net observations report
  64. GRB 231103A: Fermi GBM Final Real-time Localization
  65. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  66. Fermi-LAT gamma-ray observations of IceCube-231027A
  67. LIGO/Virgo/KAGRA S231102w: Updated Sky localization
  68. LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
  69. GRB 231101A: Glowbug gamma-ray detection
  70. GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
  71. LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
  72. New Swift-BAT/GUANO and IceCube Notices Available via GCN Kafka
  73. Fermi trigger No 720498201: Global MASTER-Net observations report
  74. GRB 231101A: Fermi GBM Final Real-time Localization
  75. GRB 231030B: GRBAlpha detection
  76. GRB 231028B: VZLUSAT-2 detection
  77. Fermi trigger No 720415645: Global MASTER-Net observations report
  78. GRB 231030B: Fermi GBM Detection
  79. GRB 231030B: AstroSat CZTI detection
  80. Fermi GRB 231030B: Global MASTER-Net observations report
  81. IPN triangulation of GRB 231020A
  82. GRB 231030B: BALROG localization (Fermi Trigger 720388704 / GRB 231030832)
  83. GRB 231030B: Fermi GBM Final Real-time Localization
  84. GRB 231028A: Swift-BAT refined analysis
  85. IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
  86. LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
  87. LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
  88. GRB 231024A: AKO Optical Counterpart Candidate
  89. GRB 231028A: CALET Gamma-Ray Burst Monitor detection
  90. Fermi GRB 231030A: Global MASTER-Net observations report
  91. GRB 231030A: Fermi GBM Final Real-time Localization
  92. LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
  93. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  95. GRID detection of GRB 231020A
  96. LIGO/Virgo/KAGRA S231029k: Global MASTER-Net observations report
  97. GRB 231028A: AstroSat CZTI detection
  98. GRB 231028A: Glowbug gamma-ray detection
  99. GRB 231028A: Fermi GBM Detection
  100. Fermi trigger No 720224759: Global MASTER-Net observations report

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