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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. GRB 240328B: Fermi GBM Final Real-time Localization
  2. GRB 240328A: Fermi GBM Final Real-time Localization
  3. IceCube Alert 240327.68: Global MASTER-Net observations report
  4. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  5. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  6. X-ray transient EP 240315a: Second epoch Chandra observations
  7. Fermi trigger No 733097506: Global MASTER-Net observations report
  8. X-ray transient EP240315a: e-MERLIN radio observations
  9. X-ray transient EP240315a: Ondrejov D50 optical limit
  10. Transient EPW20240219aa: REM optical/NIR further observations
  11. Fermi trigger No 733092476: Global MASTER-Net observations report
  12. GRB 240320A: Glowbug gamma-ray detection
  13. Fermi trigger No 732937833: Global MASTER-Net observations report
  14. GRB 240318A: Fermi GBM Observation
  15. Fermi GRB 240320A: Global MASTER-Net observations report
  16. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  17. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  18. Fermi trigger No 732657380: Global MASTER-Net observations report
  19. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  20. X-ray transient EP240315a: ATCA detection of radio counterpart
  21. GRB 240320A: Fermi GBM Final Real-time Localization
  22. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  23. GRB 240317B: Swift/BAT-GUANO Angular Error Correction
  24. Fermi Gamma-ray Burst Monitor trigger 732299243/240316686 is not a GRB
  25. X-ray transient EP 240315a: Chandra observations
  26. X-ray transient EP240315a: GTC/HiPERCAM photometry
  27. X-ray transient EP240315a: MeerKAT radio detection
  28. X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
  29. GRB 240318A: Glowbug gamma-ray detection
  30. GRB 240317C: Glowbug gamma-ray detection
  31. GRB 240318B: Glowbug gamma-ray detection
  32. X-ray transient EP240315a: PRIME near infrared detection
  33. GRB 240317B: Fermi GBM Observation
  34. X-ray transient EP240315a: 3.6 m TNG NIR detection
  35. Swift satellite in safe mode
  36. X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
  37. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  38. Fermi GRB 240318A: Global MASTER-Net observations report
  39. GRB 240318A: Fermi GBM Final Real-time Localization
  40. GRB 240317B: Swift/BAT-GUANO arcminute localization of a burst
  41. GRB 240317A: AstroSat CZTI detection
  42. GRB 240315B: AstroSat CZTI detection
  43. X-ray transient EP240315a: Kitab observatory optical upper limitns
  44. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  45. Fermi GRB 240317B: Global MASTER-Net observations report
  46. Fermi GRB 240317A: Global MASTER-Net observations report
  47. GRB 240317B: Fermi GBM Final Real-time Localization
  48. X-ray transient EP240315a: orphan FXT?
  49. GRB 240317A: Fermi GBM Final Real-time Localization
  50. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  51. X-ray transient EP240315a: GROND J-band detection
  52. X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
  53. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  54. Fermi trigger No 732299243: Global MASTER-Net observations report
  55. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  56. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  57. Einstein Probe detected of a fast X-ray transient EP240315a
  58. GRID detection of GRB 240306A
  59. Changes to the Fermi-GBM Triggering Thresholds
  60. Swift Triggers 1220155, 1220156, 1220157, 1220158, 1220160 and 1220161 were not astrophysical
  61. GRB 240315A: Fermi GBM Final Real-time Localization
  62. Swift Triggers 1220093, 1220094, 1220095 and 1220096 are not astrophysical
  63. Swift Triggers 1220090, 1220091 and 1220092 are not astrophysical
  64. Fermi GRB 240314A: Global MASTER-Net observations report
  65. GRB 240314A: Fermi GBM Final Real-time Localization
  66. GRB240204A: VIRT optical upper limit
  67. GRB 240312A: Glowbug gamma-ray detection
  68. Swift triggers 1219917, 1219917 and 1219922 were not astrophysical
  69. Swift Trigger 1219909 and 1219910 are not a astrophysical
  70. Swift Trigger 1219905 is not a GRB
  71. GRB 240312A: GECAM detection of a long burst
  72. Swift Trigger 1219874 is not astrophysical
  73. GRB 240303C: VZLUSAT-2 detection
  74. GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
  75. Fermi trigger No 731839490: Global MASTER-Net observations report
  76. Fermi-LAT gamma-ray observations of IceCube-240307A
  77. GRB 240310B: Glowbug gamma-ray detection
  78. Fermi GRB 240310A: Global MASTER-Net observations report
  79. Swift GRB240309.61: Global MASTER-Net observations report
  80. GRB 240310A: Fermi GBM Final Real-time Localization
  81. GRB 240309A: MAXI/GSC detection
  82. Swift Trigger 1219325 is not a GRB
  83. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  84. GRID detection of GRB 240229A (Updated Report)
  85. GRID detection of GRB 240229A
  86. GRB 240308A: Fermi GBM Final Localization
  87. Fermi trigger No 731571927: Global MASTER-Net observations report
  88. GRB 231215A: further radio observations with the VLA
  89. GRB 240306A: Fermi GBM observation
  90. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 240229A: Glowbug gamma-ray detection
  92. GRB 240227A (short): Glowbug gamma-ray detection
  93. IceCube Alert 240307.32: Global MASTER-Net observations report
  94. GRB 240229A: GRBAlpha detection
  95. Konus-Wind detection of GRB 231118A
  96. GRB 240306A: AstroSat CZTI detection
  97. Fermi GRB 240306A: Global MASTER-Net observations report
  98. Fermi GRB 240305A: Global MASTER-Net observations report
  99. GRB 240306A: Swift/BAT-GUANO detection of a burst
  100. GRB 240305A: Fermi GBM observation

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