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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').
  1. Fermi GRB 240305A: Global MASTER-Net observations report
  2. GRB 240306A: Swift/BAT-GUANO detection of a burst
  3. GRB 240305A: Fermi GBM observation
  4. Fermi-LAT gamma-ray observations of IceCube-240229A
  5. GRB 240305C: AstroSat CZTI detection of a short burst
  6. GRB 240306A: Fermi GBM Final Real-time Localization
  7. Swift GRB240305.18: Global MASTER-Net observations report
  8. Swift GRB240305.16: Global MASTER-Net observations report
  9. Fermi GRB 240305C: Global MASTER-Net observations report
  10. GRB 240305C: Fermi GBM Final Real-time Localization
  11. GRB 240305A: Swift/BAT-GUANO arcminute localization of a burst
  12. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  13. GRB 240218A: ALMA detection
  14. GRB 240218A: Chandra Detection and Jet Break Confirmation
  15. GRB 240305B: Fermi GBM Final Localization
  16. Fermi trigger No 731303574: Global MASTER-Net observations report
  17. Konus-Wind detection of GRB 240227A (short/hard)
  18. GRB 240303B: VZLUSAT-2 detection
  19. GRB 240229A: VZLUSAT-2 detection
  20. Improved IPN triangulation of GRB 240227A (short)
  21. IPN triangulation of GRB 240229A
  22. GRB 240305A: Fermi GBM Final Real-time Localization
  23. Swift Trigger 1218701: Yes, we triggered on Swift J151857.0-572147 again
  24. Swift Trigger 1218696: Another trigger on Swift J151857.0-572147
  25. GRB240218A: ATCA observation of the radio counterpart
  26. Transient EPW20240219aa: Optical observations with LDT
  27. Konus-Wind detection of GRB 240303B
  28. Swift Trigger 1218645: Another detection of Swift J151857.0-572147
  29. IPN triangulation of GRB 240303B
  30. Swift J151857.0-572147: Swift-BAT refined analysis
  31. GRB 240303B: Fermi GBM Detection
  32. GRB 240225B: Swift-XRT afterglow detection
  33. Swift detection of Swift J151857.0-572147
  34. GRB 240303B: CALET Gamma-Ray Burst Monitor detection
  35. Fermi trigger No 731161136: Global MASTER-Net observations report
  36. GRB 240303C: BALROG localization (Fermi Trigger 731189113 / GRB 240303837)
  37. Swift GRB 240303A: Global MASTER-Net observations report
  38. Swift J151857.0-572147: Confirmation of a new galactic transient
  39. GRB 240215A: Swift-XRT afterglow detection
  40. GRB 240303B: BALROG localization (Fermi Trigger 731161136 / GRB 240303513)
  41. GRB 240303B: Fermi GBM Final Localization
  42. GRB 240303A: Swift detection of a burst
  43. GRB 240225B: Glowbug gamma-ray detection
  44. IceCube-240229A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 240225C: Glowbug gamma-ray detection
  46. GRB 240225A (short): Glowbug gamma-ray detection
  47. GRB 240229A: DDOTI Upper Limits on the Afterglow
  48. GRB 240218A: NOEMA upper limit
  49. GRB 240229A: CALET Gamma-Ray Burst Monitor detection
  50. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  51. Swift BAT Triggers 1218081 and 1218082 are not astrophysical
  52. GRB 240225B: further SAO RAS optical observations
  53. Fermi GRB 240229A: Global MASTER-Net observations report
  54. IceCube Alert 240229.66: Global MASTER-Net observations report
  55. GRB 240225B: Swift ToO observations
  56. Konus-Wind detection of GRB 240225B (long)
  57. GRB 240229A: BALROG localization (Fermi Trigger 730908432 / GRB 240229588)
  58. GRB 240229A: Fermi GBM Final Real-time Localization
  59. GRB 240225B: VLT/X-shooter redshift
  60. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  61. GRB 240225B: 3.6m DOT observation
  62. GRB 240225B: WINTER near-IR observations and upper limits
  63. GRB 240225B: SAO RAS optical observations
  64. GRB 240226A: GRBAlpha detection
  65. GRB 240225B: Mondy afterglow observations
  66. Fermi GRB 240227A: Global MASTER-Net observations report
  67. GRB 240225B: Liverpool Telescope afterglow observations
  68. Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
  69. Swift Trigger 1217799 is not a GRB
  70. IPN triangulation of GRB 240227A (short)
  71. GRB 240225B: Liverpool Telescope optical afterglow observations
  72. GRB 240225B: NOT optical observations
  73. GRB 240218A: CMO SAI NIR upper limit
  74. Fermi GRB 240226A: Global MASTER-Net observations report
  75. Swift-BAT triggers 1217733 - 1217736 are not astrophysical events
  76. Swift-BAT triggers 1217729-1217732 are not astrophysical
  77. GRB 240227A: Fermi GBM Final Real-time Localization
  78. Fermi Gamma-ray Burst Monitor trigger 730618809/240226236 is not a GRB
  79. GRB 240225B: Nanshan/HMT optical afterglow detection
  80. GRB 240225B: CALET Gamma-Ray Burst Monitor detection
  81. GRB 240225B: Swift-XRT observations
  82. GRB 240226B: Fermi GBM Final Real-time Localization
  83. Transient EPW20240219aa: Kp-band imaging observations with NIRES
  84. Transient EPW20240219aa: J-band upper limits from WINTER
  85. GRB 240225C: CALET Gamma-Ray Burst Monitor detection
  86. GRB 240225B: GOTO detection of a candidate optical afterglow
  87. GRB 240226A: Fermi GBM Final Real-time Localization
  88. Transient EPW20240219aa: REM optical/NIR upper limits
  89. GRB 240225C: GRBAlpha detection
  90. GRB 240222A: ATCA radio observations
  91. Fermi trigger No 730618809: Global MASTER-Net observations report
  92. GRB 240225C: AstroSat CZTI detection
  93. GRB 240225B: AstroSat CZTI detection
  94. GRB 240225B: Tiled Swift observations
  95. GRB 240225B: MAXI/GSC detection
  96. Transient EPW20240219aa: Xinglong-2.16m optical upper limit
  97. GRB 240218A: VLA detection
  98. GRB 240225A: Swift/BAT-GUANO detection of a short burst
  99. GRB 240222A: GRBAlpha detection
  100. Transient EPW20240219aa: GECKO: LOAO Optical Upper Limits

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