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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. Swift Triggers 1042031 and 1042032 are not astrophysical events
  2. GRB 210406A: Mondy optical afterglow candidate
  3. GRB 210406A: Swift ToO observations
  4. GRB 210406B: Fermi GBM detection
  5. Konus-Wind detection of GRB 210406A
  6. GRB 210406A: Fermi GBM detection
  7. GRB 210406A: Mondy optical upper limit
  8. GRB 210406A: Konkoly Obs. optical upper limit
  9. GRB 210406A: BOOTES-4/MET optical upper limit
  10. GRB 210406A: A long GRB detected by INTEGRAL
  11. Integral GRB210406.72: Global MASTER-Net observations report
  12. GRB 210402A: MASTER prompt and follow up optical observation
  13. GRB 210402A: Swift/UVOT Upper Limits
  14. GRB 210402A: Fermi GBM detection
  15. GRB 210402A: Further NOT optical observations
  16. GRB 210402A: Swift-BAT refined analysis
  17. GRB 210404.141: DDOTI Upper Limits
  18. GRB 210207B: Prompt and very late time observations with HCT.
  19. GRB 210401A: GECAM detection
  20. GRB 210402A: NOT optical afterglow candidate
  21. Fermi trigger No 639199407: Global MASTER-Net observations report
  22. GRB 210402A: BOOTES-network early optical upper limit
  23. GRB 210403A: Swift-BAT refined analysis
  24. GRB 210402A: LBT observations
  25. GRB 210402A: DDOTI Upper Limits
  26. Swift GRB210403.35: Global MASTER-Net observations report
  27. GRB 210402A: Swift-XRT refined Analysis
  28. GRB 210330A: AstroSat CZTI detection
  29. GRB 210403A: Swift detection of a burst
  30. GRB 210402A: Montarrenti Observatory upper limit
  31. GRB 210328A: AstroSat CZTI detection
  32. GRB 210402A: NOT optical upper limits
  33. Konus-Wind detection of GRB 210401A
  34. GRB 210402A: Swift detection of a burst
  35. Fermi trigger No 639093861: Global MASTER-Net observations report
  36. Swift GRB210402.92: Global MASTER-Net observations report
  37. Fermi GRB 210401A: Global MASTER-Net observations report
  38. GRB 210401A: Fermi GBM Final Real-time Localization
  39. GRB 210330A: MASTER optical observation
  40. GRB 210328A: GECAM detection
  41. GRB 210330A: GECAM detection
  42. GRB 210324A: AstroSat CZTI detection
  43. GRB 210324C: AstroSat CZTI detection
  44. GRB 210328A: BALROG localization (Fermi Trigger / GRB 210328865)
  45. GRB 210328A: Fermi GBM Final Real-time Localization
  46. GRB 210326A: Insight-HXMT/HE detection
  47. GRB 210326A: Fermi GBM Final Localization
  48. Fermi trigger No 638414549: Global MASTER-Net observations report
  49. Konus-Wind detection of GRB 210324C
  50. IPN triangulation of GRB 210324C
  51. GRB 210323A: Insight-HXMT/HE detection
  52. GRB 210321A: OSN Upper Limit
  53. GRB 210323A: MASTER optical observation
  54. Fermi GRB 210324C: Global MASTER-Net observations report
  55. Fermi GRB 210324B: Global MASTER-Net observations report
  56. GRB 210323A: Swift-BAT refined analysis
  57. GRB 210323A: Gemini-North Optical Source Detection
  58. GRB 210324C: BALROG localization (Fermi Trigger 638308803 / GRB 210324833)
  59. GRB 210324C: Fermi GBM Final Real-time Localization
  60. Short GRB 210323A: GTC Observations
  61. GRB 210312B: OSN Afterglow Observations
  62. GRB 210324B: Fermi GBM Final Real-time Localization
  63. GRB 210323B: Swift ToO observations
  64. Konus-Wind detection of GRB 210323A (short)
  65. GRB 210323A: Swift/UVOT Upper Limits
  66. GRB 210323A: Classification and redshift estimation
  67. GRB 210323A: Kitab optical upper limit
  68. GRB 210323A: Fermi GBM detection
  69. GRB 210323A: Mondy optical observations, counterpart detection
  70. GRB 210324A: Fermi GBM Final Real-time Localization
  71. GRB 210318A: Swift/UVOT Upper Limits
  72. GRB 210323A: Swift-XRT refined Analysis
  73. GRB 210323A: Enhanced Swift-XRT position
  74. GRB 210323A: NOT optical afterglow candidate
  75. Swift GRB 210323A: Global MASTER-Net observations report
  76. GRB 210323B: Swift/BAT-GUANO detection and possible arcminute localization
  77. GRB 210323A: Nanshan/NEXT optical upper limit
  78. GRB 210323A: Swift detection of a short burst
  79. Fermi GBM trigger 637977270/210320996 is not a GRB
  80. GRB 210321A: Swift/UVOT Detection
  81. Konus-Wind detection of GRB 210321A
  82. GRB 210318B: Swift/UVOT Upper Limits
  83. GRB 210321A: DDOTI Position Correction
  84. IceCube Alert 210322.11: Global MASTER-Net observations report
  85. GRB 210321A: CrAO optical upper limit
  86. GRB 210321A: Swift-BAT refined analysis
  87. IceCube 135113_19489408.amon: Swift-XRT observations
  88. GRB 210321A: Mondy optical observations
  89. IceCube Astrotrack Bronze 135113_19489408.amon is likely background
  90. GRB 210321A: Xinglong GWAC-F60A optical observation
  91. GRB 210321A: Swift-XRT refined Analysis
  92. GRB 210321A: Redshift from OSIRIS/GTC
  93. GRB 210321A: NOT optical afterglow detection and redshift limit
  94. GRB 210321A: MASTER optical observation
  95. MAXI GRB210320.89: Global MASTER-Net observations report
  96. GRB 210321A: Enhanced Swift-XRT position
  97. GRB 210321A: DDOTI Afterglow Confirmation
  98. GRB 210321A: Swift/UVOT Detection
  99. GRB 210321A: Swift-XRT observations
  100. GRB 210321A: Swift detection of a burst

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