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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: Kitab optical observations
  2. Zwicky Transient Facility discovery of ZTF20abtxwfx/AT2020sev, a fast optical transient and candidate afterglow
  3. Konus-Wind detection of GRB 200826B
  4. IPN triangulation of GRB 200826B
  5. GRB 200826A: VLA Detection at 6 GHz
  6. GRB 200826A: further analysis of the Konus-Wind data and classification
  7. GRB 200826A: Swift-XRT afterglow detection
  8. GRB 200824A: Insight-HXMT/HE detection
  9. GRB 200826B: Fermi GBM detection
  10. Fermi GRB 200826B: Global MASTER-Net observations report
  11. Fermi GRB 200824A: Global MASTER-Net observations report
  12. GRB200826A: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi Short GRB (Trigger 620108997)
  13. Konus-Wind detection of GRB 200826A
  14. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  15. GRB 200826B: Fermi GBM Final Real-time Localization
  16. IPN triangulation of GRB 200826A (short/bright)
  17. GRB 200826A: Tiled Swift observations
  18. GRB 200826A: AGILE detection
  19. GRB 200826A: AstroSat CZTI detection
  20. GRB 200826A: Fermi GBM observation
  21. GRB 200826A: BALROG localization (Fermi Trigger 620108997 / GRB 200826187)
  22. Fermi GRB 200826A: Global MASTER-Net observations report
  23. GRB 200826A: Fermi GBM Final Real-time Localization
  24. GRB 200824A: Fermi GBM Final Real-time Localization
  25. Swift Trigger 992444 is due to detector noise
  26. GRB 200819A: Swift/UVOT Upper Limits
  27. Swift GRB200821.55: Global MASTER-Net observations report
  28. IceCube-200806A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  29. Swift Trigger 992444: a possible GRB 200821A
  30. Konus-Wind observation of GRB 200815A
  31. GRB 200819A: Swift-BAT refined analysis
  32. GRB 200815A: MASTER optical observations
  33. IPN triangulation of GRB 200815A (short)
  34. GRB 200819A: Optical Observations from HCT
  35. GRB 200819A: Swift-XRT refined Analysis
  36. GRB 200819A: MITSuME Ishigaki optical upper limits
  37. GRB 200729A: Lowell Discovery Telescope observations
  38. GRB 200819A: MITSuME Akeno optical upper limits
  39. Baksan Neutrino Observatory Alert 200819.88: Global MASTER-Net observations report
  40. GRB 200819A / Swift J0125.7+6303: Ondrejov Perek-2m optical limit
  41. GRB 200819A: Kitab, TSHAO optical upper limit
  42. GRB 200819A: Enhanced Swift-XRT position
  43. Swift GRB 200819A: Global MASTER-Net observations report
  44. GRB 200819A: Swift detection of a burst
  45. Baksan Neutrino Observatory Alert 200819.09: Global MASTER-Net observations report
  46. GRB 200818A: Fermi GBM Final Localization
  47. Fermi trigger No 619487843: Global MASTER-Net observations report
  48. Swift Trigger 990358 is due to detector noise
  49. Swift Trigger 989458 is due to detector noise
  50. HAWC-200814A: Retraction of burst alert
  51. Fermi GRB 200817A: Global MASTER-Net observations report
  52. GRB 200815A: CALET Gamma-Ray Burst Monitor detection of a short burst
  53. GRB 200817A: Fermi GBM Final Real-time Localization
  54. Swift trigger 990358 is not an astrophysical source
  55. Swift GRB200816.17: Global MASTER-Net observations report
  56. Fermi trigger No 619270776: Global MASTER-Net observations report
  57. Swift trigger 989458 is likely not an astrophysical source
  58. HAWC alert 200815.26: MASTER optical observations
  59. Alert from the HAWC Burst Monitor HAWC-200814A
  60. IceCube200806A: No significant detection in HAWC
  61. GRB 200811A: Fermi GBM Final Real-time Localization
  62. GRB 200811A: BALROG localization (Fermi Trigger 618851447 / GRB 200811632)
  63. GRB 200809B: Fermi GBM detection
  64. Fermi GRB 200809B: Global MASTER-Net observations report
  65. GRB 200809B: BOOTES-3/YA optical upper limit
  66. GRB 200809B: Swift-XRT afterglow detection
  67. GRB 200809B: MAXI/GSC detection
  68. GRB 200809B: Swift ToO observations
  69. GRB 200809B: AstroSat CZTI detection
  70. GRB 200809B: Swift/BAT-GUANO detection and arcminute localization
  71. GRB 200809B: Fermi GBM Final Real-time Localization
  72. GRB 200808A: AGILE detection
  73. GRB 200806A: CALET Gamma-Ray Burst Monitor detection
  74. Fermi trigger No 618642276: Global MASTER-Net observations report
  75. GRB 200809A: Fermi GBM Final Real-time Localization
  76. Fermi GRB 200808A: Global MASTER-Net observations report
  77. GRB 200808A: Fermi GBM Final Real-time Localization
  78. GRB 200806A: Nanshan/NEXT optical upper limit
  79. IPN triangulation of GRB 200805A (short)
  80. GRB 200806A: CAHA optical afterglow confirmation
  81. GRB 200803A: Chilescope optical upper limit
  82. IceCube-200806A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 200806A: VIRT optical observations
  84. GRB 200806A: Swift-BAT refined analysis
  85. GRB 200806A: Swift/UVOT Possible Detection
  86. GRB 200806A: Swift-XRT refined Analysis
  87. Fermi-LAT Gamma-ray Observations of IceCube-200806A
  88. CGBM-SPI-ACS triangulation of short GRB 200805A
  89. GRB 200806A: AbAO optical upper limit
  90. GRB 200805A: CALET Gamma-Ray Burst Monitor detection of a short burst
  91. GRB 200806A: AstroSat CZTI detection
  92. GRB 200806A: MITSuME Akeno optical upper limits
  93. GRB 200806A: Enhanced Swift-XRT position
  94. IceCube-200806A: Upper limits from Fermi-GBM Observations
  95. Swift GRB 200806A: Global MASTER-Net observations report
  96. GRB 200806A: Swift detection of a burst
  97. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  98. IceCube Alert 200806.58: Global MASTER-Net observations report
  99. GRB 200803B: MASTER possibly OT discovery
  100. GRB 200803A: AstroSat CZTI detection

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