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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-231103A: No candidates from the Zwicky Transient Facility
  2. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  3. Fermi trigger No 721204446: Global MASTER-Net observations report
  4. Fermi GRB 231108A: Global MASTER-Net observations report
  5. GRB 231108A: Fermi GBM Final Real-time Localization
  6. LIGO/Virgo/KAGRA O4 Landscape
  7. LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
  8. GRB 231106A: AstroSat CZTI detection
  9. GRB 231106A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 231104A: Swift-BAT refined analysis
  11. Fermi trigger No 721006392: Global MASTER-Net observations report
  12. Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
  13. GRB 231104A: FRAM-ORM optical limit
  14. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  15. Fermi GRB 231106A: Global MASTER-Net observations report
  16. GRB 231104A: Wendelstein Optical/Infrared Observations
  17. GRB 231104A: NuSTAR Observation of the prompt emission
  18. GRB 231106A: Fermi GBM Final Real-time Localization
  19. GRB 231104A: 3.6m DOT optical upper limit
  20. IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
  21. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  22. Fermi-LAT gamma-ray observations of IceCube-231103A
  23. GRB 231104A: NOT upper limit
  24. GRB 231104A: Fermi GBM Observation
  25. GRB 231104B: Fermi GBM Final Real-time Localization
  26. Fermi GRB 231103A: Global MASTER-Net observations report
  27. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  28. GRB 231104A: AKO Upper Limit
  29. GRB 231104A: AstroSat CZTI detection
  30. GRB 231104A: Swift-XRT refined Analysis
  31. GRB 231104A: Fermi-LAT detection
  32. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  33. GRB 231104A: Swift/UVOT Upper Limits
  34. GRB 231104A: Enhanced Swift-XRT position
  35. GRB231104A: LCOGT Optical Upper Limits
  36. GRB 231104A: Swift detection of a bright burst
  37. GRB 231104A: Fermi GBM Final Real-time Localization
  38. Swift GRB231104.07: Global MASTER-Net observations report
  39. IceCube Alert 231103.39: Global MASTER-Net observations report
  40. GRB 231103A: Fermi GBM Final Real-time Localization
  41. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  42. Fermi-LAT gamma-ray observations of IceCube-231027A
  43. LIGO/Virgo/KAGRA S231102w: Updated Sky localization
  44. LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
  45. GRB 231101A: Glowbug gamma-ray detection
  46. GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
  47. LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
  48. New Swift-BAT/GUANO and IceCube Notices Available via GCN Kafka
  49. Fermi trigger No 720498201: Global MASTER-Net observations report
  50. GRB 231101A: Fermi GBM Final Real-time Localization
  51. GRB 231030B: GRBAlpha detection
  52. GRB 231028B: VZLUSAT-2 detection
  53. Fermi trigger No 720415645: Global MASTER-Net observations report
  54. GRB 231030B: Fermi GBM Detection
  55. GRB 231030B: AstroSat CZTI detection
  56. Fermi GRB 231030B: Global MASTER-Net observations report
  57. IPN triangulation of GRB 231020A
  58. GRB 231030B: BALROG localization (Fermi Trigger 720388704 / GRB 231030832)
  59. GRB 231030B: Fermi GBM Final Real-time Localization
  60. GRB 231028A: Swift-BAT refined analysis
  61. IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
  62. LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
  63. LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
  64. GRB 231024A: AKO Optical Counterpart Candidate
  65. GRB 231028A: CALET Gamma-Ray Burst Monitor detection
  66. Fermi GRB 231030A: Global MASTER-Net observations report
  67. GRB 231030A: Fermi GBM Final Real-time Localization
  68. LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
  69. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  70. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  71. GRID detection of GRB 231020A
  72. LIGO/Virgo/KAGRA S231029k: Global MASTER-Net observations report
  73. GRB 231028A: AstroSat CZTI detection
  74. GRB 231028A: Glowbug gamma-ray detection
  75. GRB 231028A: Fermi GBM Detection
  76. Fermi trigger No 720224759: Global MASTER-Net observations report
  77. Swift GRB 231028A: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
  79. LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
  80. GRB 231028A: Swift detection of a burst
  81. GRB 231028A: Fermi GBM Final Real-time Localization
  82. IceCube Alert 231027.18: Global MASTER-Net observations report
  83. IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
  84. LIGO/Virgo/KAGRA S231025t: Global MASTER-Net observations report
  85. LIGO/Virgo/KAGRA S231025a: Global MASTER-Net observations report
  86. GRB 231019A: Glowbug gamma-ray detection
  87. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  88. GRB 231025A: Fermi GBM Observation
  89. GRB 231024A: Fermi GBM Observation
  90. GRB 231025A: Swift/BAT-GUANO detection of a likely short burst
  91. GRB 231025A: Fermi GBM Final Localization
  92. GRB 231024A: X-shooter spectroscopy of AT2023vuc/GOTO23baj reveals a young supernova with flash ionisation features
  93. GRB 231024A: LCOGT and ZTF detections of the GOTO optical counterpart candidate
  94. GRB 231020A: AstroSat CZTI detection
  95. GRB 231020B: AstroSat CZTI detection
  96. GRB 231024A: GOTO optical counterpart candidate
  97. LIGO/Virgo/KAGRA S231025a: two counterpart neutrino candidates from IceCube neutrino searches
  98. GRB 231024A: Fermi GBM Final Localization
  99. Fermi trigger No 719846439: Global MASTER-Net observations report
  100. The photometry of the transient in Messier 31 field: GMG observation

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