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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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 200826A: Swift-XRT afterglow detection
  2. GRB 200824A: Insight-HXMT/HE detection
  3. GRB 200826B: Fermi GBM detection
  4. Fermi GRB 200826B: Global MASTER-Net observations report
  5. Fermi GRB 200824A: Global MASTER-Net observations report
  6. GRB200826A: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi Short GRB (Trigger 620108997)
  7. Konus-Wind detection of GRB 200826A
  8. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  9. GRB 200826B: Fermi GBM Final Real-time Localization
  10. IPN triangulation of GRB 200826A (short/bright)
  11. GRB 200826A: Tiled Swift observations
  12. GRB 200826A: AGILE detection
  13. GRB 200826A: AstroSat CZTI detection
  14. GRB 200826A: Fermi GBM observation
  15. GRB 200826A: BALROG localization (Fermi Trigger 620108997 / GRB 200826187)
  16. Fermi GRB 200826A: Global MASTER-Net observations report
  17. GRB 200826A: Fermi GBM Final Real-time Localization
  18. GRB 200824A: Fermi GBM Final Real-time Localization
  19. Swift Trigger 992444 is due to detector noise
  20. GRB 200819A: Swift/UVOT Upper Limits
  21. Swift GRB200821.55: Global MASTER-Net observations report
  22. IceCube-200806A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  23. Swift Trigger 992444: a possible GRB 200821A
  24. Konus-Wind observation of GRB 200815A
  25. GRB 200819A: Swift-BAT refined analysis
  26. GRB 200815A: MASTER optical observations
  27. IPN triangulation of GRB 200815A (short)
  28. GRB 200819A: Optical Observations from HCT
  29. GRB 200819A: Swift-XRT refined Analysis
  30. GRB 200819A: MITSuME Ishigaki optical upper limits
  31. GRB 200729A: Lowell Discovery Telescope observations
  32. GRB 200819A: MITSuME Akeno optical upper limits
  33. Baksan Neutrino Observatory Alert 200819.88: Global MASTER-Net observations report
  34. GRB 200819A / Swift J0125.7+6303: Ondrejov Perek-2m optical limit
  35. GRB 200819A: Kitab, TSHAO optical upper limit
  36. GRB 200819A: Enhanced Swift-XRT position
  37. Swift GRB 200819A: Global MASTER-Net observations report
  38. GRB 200819A: Swift detection of a burst
  39. Baksan Neutrino Observatory Alert 200819.09: Global MASTER-Net observations report
  40. GRB 200818A: Fermi GBM Final Localization
  41. Fermi trigger No 619487843: Global MASTER-Net observations report
  42. Swift Trigger 990358 is due to detector noise
  43. Swift Trigger 989458 is due to detector noise
  44. HAWC-200814A: Retraction of burst alert
  45. Fermi GRB 200817A: Global MASTER-Net observations report
  46. GRB 200815A: CALET Gamma-Ray Burst Monitor detection of a short burst
  47. GRB 200817A: Fermi GBM Final Real-time Localization
  48. Swift trigger 990358 is not an astrophysical source
  49. Swift GRB200816.17: Global MASTER-Net observations report
  50. Fermi trigger No 619270776: Global MASTER-Net observations report
  51. Swift trigger 989458 is likely not an astrophysical source
  52. HAWC alert 200815.26: MASTER optical observations
  53. Alert from the HAWC Burst Monitor HAWC-200814A
  54. IceCube200806A: No significant detection in HAWC
  55. GRB 200811A: Fermi GBM Final Real-time Localization
  56. GRB 200811A: BALROG localization (Fermi Trigger 618851447 / GRB 200811632)
  57. GRB 200809B: Fermi GBM detection
  58. Fermi GRB 200809B: Global MASTER-Net observations report
  59. GRB 200809B: BOOTES-3/YA optical upper limit
  60. GRB 200809B: Swift-XRT afterglow detection
  61. GRB 200809B: MAXI/GSC detection
  62. GRB 200809B: Swift ToO observations
  63. GRB 200809B: AstroSat CZTI detection
  64. GRB 200809B: Swift/BAT-GUANO detection and arcminute localization
  65. GRB 200809B: Fermi GBM Final Real-time Localization
  66. GRB 200808A: AGILE detection
  67. GRB 200806A: CALET Gamma-Ray Burst Monitor detection
  68. Fermi trigger No 618642276: Global MASTER-Net observations report
  69. GRB 200809A: Fermi GBM Final Real-time Localization
  70. Fermi GRB 200808A: Global MASTER-Net observations report
  71. GRB 200808A: Fermi GBM Final Real-time Localization
  72. GRB 200806A: Nanshan/NEXT optical upper limit
  73. IPN triangulation of GRB 200805A (short)
  74. GRB 200806A: CAHA optical afterglow confirmation
  75. GRB 200803A: Chilescope optical upper limit
  76. IceCube-200806A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 200806A: VIRT optical observations
  78. GRB 200806A: Swift-BAT refined analysis
  79. GRB 200806A: Swift/UVOT Possible Detection
  80. GRB 200806A: Swift-XRT refined Analysis
  81. Fermi-LAT Gamma-ray Observations of IceCube-200806A
  82. CGBM-SPI-ACS triangulation of short GRB 200805A
  83. GRB 200806A: AbAO optical upper limit
  84. GRB 200805A: CALET Gamma-Ray Burst Monitor detection of a short burst
  85. GRB 200806A: AstroSat CZTI detection
  86. GRB 200806A: MITSuME Akeno optical upper limits
  87. GRB 200806A: Enhanced Swift-XRT position
  88. IceCube-200806A: Upper limits from Fermi-GBM Observations
  89. Swift GRB 200806A: Global MASTER-Net observations report
  90. GRB 200806A: Swift detection of a burst
  91. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  92. IceCube Alert 200806.58: Global MASTER-Net observations report
  93. GRB 200803B: MASTER possibly OT discovery
  94. GRB 200803A: AstroSat CZTI detection
  95. GRB 200803A: Fermi GBM detection
  96. GRB 200803A: Swift-XRT afterglow detection
  97. Fermi GRB 200803B: Global MASTER-Net observations report
  98. GRB 200803A: Fermi-LAT detection
  99. GRB 200803A: MASTER optical counterpart discovery
  100. GRB 200803B: Fermi GBM Final Real-time Localization

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