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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. Swift trigger 989458 is likely not an astrophysical source
  2. HAWC alert 200815.26: MASTER optical observations
  3. Alert from the HAWC Burst Monitor HAWC-200814A
  4. IceCube200806A: No significant detection in HAWC
  5. GRB 200811A: Fermi GBM Final Real-time Localization
  6. GRB 200811A: BALROG localization (Fermi Trigger 618851447 / GRB 200811632)
  7. GRB 200809B: Fermi GBM detection
  8. Fermi GRB 200809B: Global MASTER-Net observations report
  9. GRB 200809B: BOOTES-3/YA optical upper limit
  10. GRB 200809B: Swift-XRT afterglow detection
  11. GRB 200809B: MAXI/GSC detection
  12. GRB 200809B: Swift ToO observations
  13. GRB 200809B: AstroSat CZTI detection
  14. GRB 200809B: Swift/BAT-GUANO detection and arcminute localization
  15. GRB 200809B: Fermi GBM Final Real-time Localization
  16. GRB 200808A: AGILE detection
  17. GRB 200806A: CALET Gamma-Ray Burst Monitor detection
  18. Fermi trigger No 618642276: Global MASTER-Net observations report
  19. GRB 200809A: Fermi GBM Final Real-time Localization
  20. Fermi GRB 200808A: Global MASTER-Net observations report
  21. GRB 200808A: Fermi GBM Final Real-time Localization
  22. GRB 200806A: Nanshan/NEXT optical upper limit
  23. IPN triangulation of GRB 200805A (short)
  24. GRB 200806A: CAHA optical afterglow confirmation
  25. GRB 200803A: Chilescope optical upper limit
  26. IceCube-200806A: Upper limits from a search for additional neutrino events in IceCube
  27. GRB 200806A: VIRT optical observations
  28. GRB 200806A: Swift-BAT refined analysis
  29. GRB 200806A: Swift/UVOT Possible Detection
  30. GRB 200806A: Swift-XRT refined Analysis
  31. Fermi-LAT Gamma-ray Observations of IceCube-200806A
  32. CGBM-SPI-ACS triangulation of short GRB 200805A
  33. GRB 200806A: AbAO optical upper limit
  34. GRB 200805A: CALET Gamma-Ray Burst Monitor detection of a short burst
  35. GRB 200806A: AstroSat CZTI detection
  36. GRB 200806A: MITSuME Akeno optical upper limits
  37. GRB 200806A: Enhanced Swift-XRT position
  38. IceCube-200806A: Upper limits from Fermi-GBM Observations
  39. Swift GRB 200806A: Global MASTER-Net observations report
  40. GRB 200806A: Swift detection of a burst
  41. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  42. IceCube Alert 200806.58: Global MASTER-Net observations report
  43. GRB 200803B: MASTER possibly OT discovery
  44. GRB 200803A: AstroSat CZTI detection
  45. GRB 200803A: Fermi GBM detection
  46. GRB 200803A: Swift-XRT afterglow detection
  47. Fermi GRB 200803B: Global MASTER-Net observations report
  48. GRB 200803A: Fermi-LAT detection
  49. GRB 200803A: MASTER optical counterpart discovery
  50. GRB 200803B: Fermi GBM Final Real-time Localization
  51. GRB 200803A: Tiled Swift observations
  52. LAT GRB200803.15: Global MASTER-Net observations report
  53. Fermi GRB 200803A: Global MASTER-Net observations report
  54. GRB 200801B: AstroSat CZTI detection
  55. GRB 200803A: Fermi GBM Final Real-time Localization
  56. Fermi GRB 200801B: Global MASTER-Net observations report
  57. Fermi GRB 200802A: Global MASTER-Net observations report
  58. AX J1846.4-0258: Swift-BAT refined analysis
  59. Konus-Wind detection of GRB 200729A
  60. GRB 200802A: BALROG localization (Fermi Trigger 618061611 / GRB 200802491)
  61. GRB 200802A: Fermi GBM Final Real-time Localization
  62. GRB 200801C: BOOTES-1 and BOOTES-2 optical limits
  63. Fermi GRB 200801A: Global MASTER-Net observations report
  64. Swift Detection of an SGR-like flare from AX J1846.4-0258
  65. Swift GRB200801.84: Global MASTER-Net observations report
  66. GRB 200801B: BALROG localization (Fermi Trigger 617988951 / GRB 200801650)
  67. GRB 200801B: Fermi GBM Final Real-time Localization
  68. GRB 200801A: Fermi GBM Final Real-time Localization
  69. GRB 200729A: RT-22 observations at 36.8 GHz
  70. GRB 200729A: VLA Observations
  71. GRB 200729A: Nanshan/NEXT optical upper limit
  72. GRB 200729A: Swift-BAT refined analysis
  73. GRB 200729A: further analysis of the NOT data
  74. GRB 200729A: Swift/UVOT Upper Limits
  75. GRB 200729A: Swift-XRT refined Analysis
  76. GRB 200729A: HST imaging
  77. Fermi-GBM Sub-Threshold candidate for GRB 200729A
  78. GRB 200729A: IceCube neutrino search
  79. GRB 200729A: Pan-STARRS pre-explosion source detection
  80. GRB 200729A: Spitzer archival source detection
  81. GRB 200729A: TNG NIR upper limits
  82. GRB 200729A: NOT optical upper limits
  83. GRB 200729A: Enhanced Swift-XRT position
  84. GRB200729A: BOOTES-1 optical upper limit
  85. Swift GRB 200729A: Global MASTER-Net observations report
  86. GRB 200729A: Swift detection of a burst
  87. IceCube Alert 200728.35: Global MASTER-Net observations report
  88. IceCube GCN Notice 134327_10548129 retraction
  89. Baksan Neutrino Observatory Alert 200726.66: Global MASTER-Net observations report
  90. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  91. GRB 200723A: Swift ToO observations
  92. GRB 200723A: GOTO candidate afterglow and host galaxy
  93. GRB 200724A: Fermi GBM Final Real-time Localization
  94. Fermi GRB 200723A: Global MASTER-Net observations report
  95. GRB 200723A: BALROG localization (Fermi Trigger 617214929 / GRB 200723691)
  96. GRB 200723A: Fermi GBM Final Real-time Localization
  97. GRB 200716C: Kitab optical observations
  98. GRB 200722A: BALROG localization (Fermi Trigger 617076900 / GRB 200722094)
  99. GRB 200716C: CAHA optical observation // Anomalous light curve behavior?
  100. GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations

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