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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-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  2. GRB 240229A: Glowbug gamma-ray detection
  3. GRB 240227A (short): Glowbug gamma-ray detection
  4. IceCube Alert 240307.32: Global MASTER-Net observations report
  5. GRB 240229A: GRBAlpha detection
  6. Konus-Wind detection of GRB 231118A
  7. GRB 240306A: AstroSat CZTI detection
  8. Fermi GRB 240306A: Global MASTER-Net observations report
  9. Fermi GRB 240305A: Global MASTER-Net observations report
  10. GRB 240306A: Swift/BAT-GUANO detection of a burst
  11. GRB 240305A: Fermi GBM observation
  12. Fermi-LAT gamma-ray observations of IceCube-240229A
  13. GRB 240305C: AstroSat CZTI detection of a short burst
  14. GRB 240306A: Fermi GBM Final Real-time Localization
  15. Swift GRB240305.18: Global MASTER-Net observations report
  16. Swift GRB240305.16: Global MASTER-Net observations report
  17. Fermi GRB 240305C: Global MASTER-Net observations report
  18. GRB 240305C: Fermi GBM Final Real-time Localization
  19. GRB 240305A: Swift/BAT-GUANO arcminute localization of a burst
  20. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  21. GRB 240218A: ALMA detection
  22. GRB 240218A: Chandra Detection and Jet Break Confirmation
  23. GRB 240305B: Fermi GBM Final Localization
  24. Fermi trigger No 731303574: Global MASTER-Net observations report
  25. Konus-Wind detection of GRB 240227A (short/hard)
  26. GRB 240303B: VZLUSAT-2 detection
  27. GRB 240229A: VZLUSAT-2 detection
  28. Improved IPN triangulation of GRB 240227A (short)
  29. IPN triangulation of GRB 240229A
  30. GRB 240305A: Fermi GBM Final Real-time Localization
  31. Swift Trigger 1218701: Yes, we triggered on Swift J151857.0-572147 again
  32. Swift Trigger 1218696: Another trigger on Swift J151857.0-572147
  33. GRB240218A: ATCA observation of the radio counterpart
  34. Transient EPW20240219aa: Optical observations with LDT
  35. Konus-Wind detection of GRB 240303B
  36. Swift Trigger 1218645: Another detection of Swift J151857.0-572147
  37. IPN triangulation of GRB 240303B
  38. Swift J151857.0-572147: Swift-BAT refined analysis
  39. GRB 240303B: Fermi GBM Detection
  40. GRB 240225B: Swift-XRT afterglow detection
  41. Swift detection of Swift J151857.0-572147
  42. GRB 240303B: CALET Gamma-Ray Burst Monitor detection
  43. Fermi trigger No 731161136: Global MASTER-Net observations report
  44. GRB 240303C: BALROG localization (Fermi Trigger 731189113 / GRB 240303837)
  45. Swift GRB 240303A: Global MASTER-Net observations report
  46. Swift J151857.0-572147: Confirmation of a new galactic transient
  47. GRB 240215A: Swift-XRT afterglow detection
  48. GRB 240303B: BALROG localization (Fermi Trigger 731161136 / GRB 240303513)
  49. GRB 240303B: Fermi GBM Final Localization
  50. GRB 240303A: Swift detection of a burst
  51. GRB 240225B: Glowbug gamma-ray detection
  52. IceCube-240229A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 240225C: Glowbug gamma-ray detection
  54. GRB 240225A (short): Glowbug gamma-ray detection
  55. GRB 240229A: DDOTI Upper Limits on the Afterglow
  56. GRB 240218A: NOEMA upper limit
  57. GRB 240229A: CALET Gamma-Ray Burst Monitor detection
  58. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  59. Swift BAT Triggers 1218081 and 1218082 are not astrophysical
  60. GRB 240225B: further SAO RAS optical observations
  61. Fermi GRB 240229A: Global MASTER-Net observations report
  62. IceCube Alert 240229.66: Global MASTER-Net observations report
  63. GRB 240225B: Swift ToO observations
  64. Konus-Wind detection of GRB 240225B (long)
  65. GRB 240229A: BALROG localization (Fermi Trigger 730908432 / GRB 240229588)
  66. GRB 240229A: Fermi GBM Final Real-time Localization
  67. GRB 240225B: VLT/X-shooter redshift
  68. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  69. GRB 240225B: 3.6m DOT observation
  70. GRB 240225B: WINTER near-IR observations and upper limits
  71. GRB 240225B: SAO RAS optical observations
  72. GRB 240226A: GRBAlpha detection
  73. GRB 240225B: Mondy afterglow observations
  74. Fermi GRB 240227A: Global MASTER-Net observations report
  75. GRB 240225B: Liverpool Telescope afterglow observations
  76. Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
  77. Swift Trigger 1217799 is not a GRB
  78. IPN triangulation of GRB 240227A (short)
  79. GRB 240225B: Liverpool Telescope optical afterglow observations
  80. GRB 240225B: NOT optical observations
  81. GRB 240218A: CMO SAI NIR upper limit
  82. Fermi GRB 240226A: Global MASTER-Net observations report
  83. Swift-BAT triggers 1217733 - 1217736 are not astrophysical events
  84. Swift-BAT triggers 1217729-1217732 are not astrophysical
  85. GRB 240227A: Fermi GBM Final Real-time Localization
  86. Fermi Gamma-ray Burst Monitor trigger 730618809/240226236 is not a GRB
  87. GRB 240225B: Nanshan/HMT optical afterglow detection
  88. GRB 240225B: CALET Gamma-Ray Burst Monitor detection
  89. GRB 240225B: Swift-XRT observations
  90. GRB 240226B: Fermi GBM Final Real-time Localization
  91. Transient EPW20240219aa: Kp-band imaging observations with NIRES
  92. Transient EPW20240219aa: J-band upper limits from WINTER
  93. GRB 240225C: CALET Gamma-Ray Burst Monitor detection
  94. GRB 240225B: GOTO detection of a candidate optical afterglow
  95. GRB 240226A: Fermi GBM Final Real-time Localization
  96. Transient EPW20240219aa: REM optical/NIR upper limits
  97. GRB 240225C: GRBAlpha detection
  98. GRB 240222A: ATCA radio observations
  99. Fermi trigger No 730618809: Global MASTER-Net observations report
  100. GRB 240225C: AstroSat CZTI detection

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