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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. IPN triangulation of GRB 230308A (short/bright)
  2. Fermi GRB 230314A: Global MASTER-Net observations report
  3. GRB 230307A: ATCA radio detection
  4. GRB 230314A: Fermi GBM Final Real-time Localization
  5. VZLUSAT-2 detection of SGR 1806-20
  6. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  7. GRB 230307A: Swift/UVOT detection
  8. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  9. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  10. Fermi GRB 230313A: Global MASTER-Net observations report
  11. GRB 230313A: Fermi GBM Final Real-time Localization
  12. GRB 230307A: soft X-ray detection with LEIA
  13. GRB 230307A: Swift-XRT afterglow detection
  14. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  15. Swift GRB230311.85: Global MASTER-Net observations report
  16. Swift GRB230311.83: Global MASTER-Net observations report
  17. Further improved IPN localization for GRB 230307A
  18. Swift GRB230311.81: Global MASTER-Net observations report
  19. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  20. Swift GRB230311.84: Global MASTER-Net observations report
  21. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  22. Swift GRB230311.82: Global MASTER-Net observations report
  23. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  24. Alert from the HAWC Burst Monitor HAWC-230311A
  25. TESS Detection of the Optical Afterglow of GRB230307A
  26. GRB 230308A: CALET Gamma-Ray Burst Monitor detection
  27. Trigger 1159327: Swift detection of SGR1806-20
  28. GRB 230310A: AstroSat CZTI detection
  29. GRB 230307A: GECKO optical observations and detections of the afterglow
  30. GRB 230307A: MAXI/GSC upper limit
  31. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  32. Fermi GRB 230310A: Global MASTER-Net observations report
  33. GRB 230310A: Fermi GBM Final Real-time Localization
  34. GRB 230307A: AGILE/MCAL analysis
  35. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  36. GRB 230307A: Erratum of the GCN 33441
  37. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  38. GRB 230308A: Fermi GBM detection
  39. GRB 230307A: Possible optical afterglow
  40. GRB 230307A: ASO-S/HXI detection
  41. GRB 230307A: AstroSat LAXPC detection
  42. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  43. GRB 230308A: AGILE/MCAL detection
  44. GRB 230307A: optical upper limit
  45. GRB 230217A: ATCA rapid-response radio detection
  46. Swift Trigger 1159108 is not a GRB
  47. GRB 230307A: Swift/BAT upper limits on the early afterglow
  48. GRB 230307A: Upper limits from a neutrino search with IceCube
  49. GRB 230307A: Swift-XRT observations
  50. Fermi GRB 230307A: Global MASTER-Net observations report
  51. Konus-Wind detection of GRB 230307A
  52. GRB 230228A: VIRT Optical Upper Limit
  53. Improved IPN localization for GRB 230307A
  54. GRB 230307A: VZLUSAT-2 detection
  55. GRB 230304B: CALET Gamma-Ray Burst Monitor detection
  56. Fermi GRB 230308A: Global MASTER-Net observations report
  57. GRB 230308A: BALROG localization (Fermi Trigger 699975152 / GRB 230308564)
  58. GRB 230308A: Fermi GBM Final Real-time Localization
  59. GRB 230307A: Tiled Swift observations
  60. GRB 230307A: Detection by GRBAlpha
  61. GRB 230305A: Detection by GRBAlpha
  62. GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  63. GRB 230307A: AstroSat CZTI detection
  64. GRB 230307A: possibly the second highest GRB energy fluence ever identified
  65. IPN triangulation of GRB 230307A (long/very bright)
  66. GRB 230307A: AGILE/MCAL detection
  67. GRB 230307A: Fermi GBM Observation of a very bright burst
  68. Solar Orbiter STIX observation of GRB 230307A
  69. IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
  70. Fermi-LAT gamma-ray observations of IceCube-230306A
  71. GRB 230307A: Fermi GBM detection of a very bright GRB
  72. GRB 230307A: GECAM detection of an extremely bright burst
  73. GRB 230307A: Fermi GBM Final Real-time Localization
  74. Fermi trigger No 699811746: Global MASTER-Net observations report
  75. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  76. IceCube Alert 230306.46: Global MASTER-Net observations report
  77. GRB 230304C: AstroSat CZTI detection
  78. GRB 230304B: AstroSat CZTI detection
  79. GRB 230304A: AstroSat CZTI detection
  80. GRB 230304B: Detection by GRBAlpha
  81. GRB 230304C: Fermi GBM Final Real-time Localization
  82. GRB 230304B: Fermi GBM Final Real-time Localization
  83. GRB 230304A: Fermi GBM Final Real-time Localization
  84. GRB 230228A: 6 GHz VLA radio upper limit
  85. GRB 230228A: Swift-BAT refined analysis
  86. GRB 230228A: Swift/UVOT Upper Limits
  87. Fermi GRB 230301B: Global MASTER-Net observations report
  88. GRB 230301B: Fermi GBM Final Real-time Localization
  89. GRB 230228A: Fermi GBM Observation
  90. Fermi trigger No 699294715: Global MASTER-Net observations report
  91. GRB 230228A: OSN optical upper limit
  92. Fermi trigger No 699311646: Global MASTER-Net observations report
  93. GRB 230301A: Fermi GBM Final Real-time Localization
  94. GRB 230228A: Swift-XRT refined Analysis
  95. GRB 230228A: Mondy optical upper limit
  96. GRB 230228A: Enhanced Swift-XRT position
  97. GRB 230228A: Nanshan/NEXT optical upper limit
  98. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  99. GRB 230228A: Prompt enhanced Swift-XRT position
  100. GRB 230228A: Swift detection of a possibly short burst

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