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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 230307A: short mininum variability timescale compatible with a merger origin
  2. GRB 230405B: Swift/UVOT Upper Limits
  3. GRB 230405B: AstroSat CZTI detection
  4. GRB 230405B: Enhanced Swift-XRT position
  5. Swift GRB 230405B: Global MASTER-Net observations report
  6. GRB 230405B: Prompt enhanced Swift-XRT position
  7. GRB 230405B: Swift detection of a burst
  8. GRB 230405B: Fermi GBM Final Real-time Localization
  9. GRB 230307A: JWST observations consistent with the presence of a kilonova
  10. Fermi GRB 230405A: Global MASTER-Net observations report
  11. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  12. GRB 230405A: Fermi GBM Final Real-time Localization
  13. GRB 230404A: AstroSat CZTI detection
  14. GRB 230404A: Fermi GBM Final Real-time Localization
  15. GRB 230402A: CALET Gamma-Ray Burst Monitor detection
  16. GRB 230402A: AstroSat CZTI detection
  17. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  18. IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
  19. GRB 230328B: Multa observatory optical afterglow observation
  20. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  21. GRB 230228A: detection by GTC of the potential host galaxy
  22. GRB 230328B: Swift/UVOT Detection
  23. GRB 230402A: AGILE detection
  24. Fermi GRB 230402A: Global MASTER-Net observations report
  25. GRB 230402A: Fermi GBM Final Real-time Localization
  26. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  27. GRB 230307A: Bad Time Intervals for Fermi GBM data
  28. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  29. GRB 230328B: CAHA 2.2m/CAFOS detection
  30. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 230328B: 3.6m DOT multiband optical observation
  32. Fermi trigger No 701883729: Global MASTER-Net observations report
  33. GRB 230330B: Fermi GBM Final Localization
  34. Konus-Wind detection of GRB 230328B
  35. GRB 230328B: GRBAlpha detection
  36. GRB 230330A: Fermi GBM Final Real-time Localization
  37. GRB 230328B: Swift-BAT refined analysis
  38. GRB 230328B: Nanshan/NEXT 2nd optical observation
  39. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  40. GRB 230328B: Liverpool Telescope afterglow detection
  41. GRB 230328B: OHP/T120 optical observations
  42. GRB 230328B: GIT optical follow-up
  43. GRB 230328B: OASDG optical observations
  44. GRB 230328B: Nanshan/NEXT optical upper limit
  45. GRB 230328B: Swift-XRT refined Analysis
  46. GRB 230328B: AstroSat CZTI detection
  47. GRB 230328B: Fermi GBM observation
  48. GRB 230328B: Mondy, AbAO and Kitab optical observations
  49. GRB 230328B: Enhanced Swift-XRT position
  50. GRB 230328B: Mondy optical afterglow confirmation
  51. GRB 230328B: Swift detection of a burst with an optical afterglow
  52. GRB 230328B: Fermi GBM Final Real-time Localization
  53. Fermi GRB 230328A: Global MASTER-Net observations report
  54. GRB 230328A: Fermi GBM Final Real-time Localization
  55. GRB 230325A: Swift-BAT refined analysis
  56. GRB 230325A: Swift/UVOT Upper Limits
  57. GRB 230325A: X-shooter optical afterglow and redshift
  58. GRB 230325A: Swift-XRT refined Analysis
  59. GRB 230322B: Swift-BAT refined analysis
  60. GRB 230325A: Enhanced Swift-XRT position
  61. GRB 230325A: Prompt enhanced Swift-XRT position
  62. GRB 230325A: Swift detection of a burst
  63. GRB 230320B: Fermi GBM Observation
  64. Fermi trigger No 701313046: Global MASTER-Net observations report
  65. Fermi trigger No 701321709: Global MASTER-Net observations report
  66. GRB 230322B: Swift/UVOT Detection
  67. Konus-Wind detection of GRB 230309A
  68. Konus-Wind detection of GRB 230308A
  69. Konus-Wind detection of GRB 230304B
  70. GRB 230322B: Swift-XRT refined Analysis
  71. GRB 230322B: Enhanced Swift-XRT position
  72. Swift GRB 230322B: Global MASTER-Net observations report
  73. GRB 230322B: Swift detection of a burst with optical counterpart
  74. GRB 230322A: Fermi GBM Final Real-time Localization
  75. GRB 230320B: GRBAlpha detection
  76. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  78. Fermi trigger No 701071944: Global MASTER-Net observations report
  79. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  80. Fermi GRB 230320A: Global MASTER-Net observations report
  81. Fermi GRB 230321A: Global MASTER-Net observations report
  82. Fermi trigger No 701058254: Global MASTER-Net observations report
  83. SGR 1806-20: Correction to GCN 33494
  84. INTEGRAL detection of a burst from SGR 1806-200
  85. GRB 230321B: AstroSat CZTI detection
  86. GRB 230320B: AstroSat CZTI detection
  87. GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  88. GRB 230321A: Fermi GBM Final Real-time Localization
  89. GRB 230320A: Fermi GBM Final Real-time Localization
  90. GRB 230314A: TURBO Optical Upper Limit
  91. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  92. Fermi trigger No 700976129: Global MASTER-Net observations report
  93. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  94. IPN triangulation of GRB 230309A
  95. Fermi GRB 230316A: Global MASTER-Net observations report
  96. GRB 230304D: AstroSat CZTI detection
  97. GRB 230316A: Fermi GBM Final Real-time Localization
  98. IPN triangulation of GRB 230304B
  99. GRB 230313A: AstroSat CZTI detection
  100. GRB 230307A: Far off-axis NuSTAR detection of the GRB

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