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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 231106A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 231104A: Swift-BAT refined analysis
  3. Fermi trigger No 721006392: Global MASTER-Net observations report
  4. Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
  5. GRB 231104A: FRAM-ORM optical limit
  6. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  7. Fermi GRB 231106A: Global MASTER-Net observations report
  8. GRB 231104A: Wendelstein Optical/Infrared Observations
  9. GRB 231104A: NuSTAR Observation of the prompt emission
  10. GRB 231106A: Fermi GBM Final Real-time Localization
  11. GRB 231104A: 3.6m DOT optical upper limit
  12. IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
  13. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  14. Fermi-LAT gamma-ray observations of IceCube-231103A
  15. GRB 231104A: NOT upper limit
  16. GRB 231104A: Fermi GBM Observation
  17. GRB 231104B: Fermi GBM Final Real-time Localization
  18. Fermi GRB 231103A: Global MASTER-Net observations report
  19. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  20. GRB 231104A: AKO Upper Limit
  21. GRB 231104A: AstroSat CZTI detection
  22. GRB 231104A: Swift-XRT refined Analysis
  23. GRB 231104A: Fermi-LAT detection
  24. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  25. GRB 231104A: Swift/UVOT Upper Limits
  26. GRB 231104A: Enhanced Swift-XRT position
  27. GRB231104A: LCOGT Optical Upper Limits
  28. GRB 231104A: Swift detection of a bright burst
  29. GRB 231104A: Fermi GBM Final Real-time Localization
  30. Swift GRB231104.07: Global MASTER-Net observations report
  31. IceCube Alert 231103.39: Global MASTER-Net observations report
  32. GRB 231103A: Fermi GBM Final Real-time Localization
  33. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  34. Fermi-LAT gamma-ray observations of IceCube-231027A
  35. LIGO/Virgo/KAGRA S231102w: Updated Sky localization
  36. LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
  37. GRB 231101A: Glowbug gamma-ray detection
  38. GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
  39. LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
  40. New Swift-BAT/GUANO and IceCube Notices Available via GCN Kafka
  41. Fermi trigger No 720498201: Global MASTER-Net observations report
  42. GRB 231101A: Fermi GBM Final Real-time Localization
  43. GRB 231030B: GRBAlpha detection
  44. GRB 231028B: VZLUSAT-2 detection
  45. Fermi trigger No 720415645: Global MASTER-Net observations report
  46. GRB 231030B: Fermi GBM Detection
  47. GRB 231030B: AstroSat CZTI detection
  48. Fermi GRB 231030B: Global MASTER-Net observations report
  49. IPN triangulation of GRB 231020A
  50. GRB 231030B: BALROG localization (Fermi Trigger 720388704 / GRB 231030832)
  51. GRB 231030B: Fermi GBM Final Real-time Localization
  52. GRB 231028A: Swift-BAT refined analysis
  53. IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
  54. LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
  55. LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
  56. GRB 231024A: AKO Optical Counterpart Candidate
  57. GRB 231028A: CALET Gamma-Ray Burst Monitor detection
  58. Fermi GRB 231030A: Global MASTER-Net observations report
  59. GRB 231030A: Fermi GBM Final Real-time Localization
  60. LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
  61. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  62. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  63. GRID detection of GRB 231020A
  64. LIGO/Virgo/KAGRA S231029k: Global MASTER-Net observations report
  65. GRB 231028A: AstroSat CZTI detection
  66. GRB 231028A: Glowbug gamma-ray detection
  67. GRB 231028A: Fermi GBM Detection
  68. Fermi trigger No 720224759: Global MASTER-Net observations report
  69. Swift GRB 231028A: Global MASTER-Net observations report
  70. LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
  71. LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
  72. GRB 231028A: Swift detection of a burst
  73. GRB 231028A: Fermi GBM Final Real-time Localization
  74. IceCube Alert 231027.18: Global MASTER-Net observations report
  75. IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
  76. LIGO/Virgo/KAGRA S231025t: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S231025a: Global MASTER-Net observations report
  78. GRB 231019A: Glowbug gamma-ray detection
  79. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  80. GRB 231025A: Fermi GBM Observation
  81. GRB 231024A: Fermi GBM Observation
  82. GRB 231025A: Swift/BAT-GUANO detection of a likely short burst
  83. GRB 231025A: Fermi GBM Final Localization
  84. GRB 231024A: X-shooter spectroscopy of AT2023vuc/GOTO23baj reveals a young supernova with flash ionisation features
  85. GRB 231024A: LCOGT and ZTF detections of the GOTO optical counterpart candidate
  86. GRB 231020A: AstroSat CZTI detection
  87. GRB 231020B: AstroSat CZTI detection
  88. GRB 231024A: GOTO optical counterpart candidate
  89. LIGO/Virgo/KAGRA S231025a: two counterpart neutrino candidates from IceCube neutrino searches
  90. GRB 231024A: Fermi GBM Final Localization
  91. Fermi trigger No 719846439: Global MASTER-Net observations report
  92. The photometry of the transient in Messier 31 field: GMG observation
  93. GRB 231018A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  94. LIGO/Virgo/KAGRA S231020bw: Upper limits from Swift/BAT-GUANO
  95. LIGO/Virgo/KAGRA S231021az: Coverage and upper limits from MAXI/GSC observations
  96. LIGO/Virgo/KAGRA S231020bw: Updated Sky localization
  97. GRB 231020A: Fermi GBM Detection
  98. GRID detection of GRB 231004A
  99. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  100. GRB 231019A: VZLUSAT-2 detection

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