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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 191031A: Fermi GBM Final Real-time Localization
  2. GRB 191031A: Swift detection of a burst
  3. Konus-Wind observation of GRB 191027A
  4. GRB 191029A: CORRECTED Swift-XRT refined analysis
  5. GRB 191019A: Zadko Telescope optical observations
  6. GRB 191029A: Swift/UVOT Upper Limits
  7. Correction to GCN 26079 regarding GRB 191027A
  8. GRB 191029A: Enhanced Swift-XRT position
  9. GRB 191029A: Swift-XRT refined Analysis
  10. GRB 191028B: MASTER optical observation
  11. GRB 191029A: BOOTES-4/MET optical limit
  12. GRB 191029A: iTelescope optical upper limits
  13. GRB 191029A: Swift-XRT observations
  14. Konus-Wind observation of GRB 191025B
  15. GRB 191029A: Swift detection of a burst
  16. IPN triangulation of GRB 191027A
  17. IPN triangulation of GRB 191025B (short)
  18. GRB 191028B: BALROG localization (Fermi Trigger 593964489 / GRB 191028589)
  19. GRB 191028B: Fermi GBM Final Real-time Localization
  20. Fermi GBM trigger 593931926/191028212 is not a GRB
  21. GRB 191028A: Fermi GBM Final Real-time Localization
  22. GRB 191025B: Insight-HXMT/HE detection
  23. Swift/BAT Trigger 931384 is not a GRB ( 191025A )
  24. GRB 191027A: BALROG localization (Fermi Trigger 593882352 / GRB 191027638)
  25. GRB 191027A: Fermi GBM Final Real-time Localization
  26. GRB 191026B: AstroSat CZTI detection
  27. GRB 191026A: Fermi GBM Final Real-time Localization
  28. Swift Trigger 931484 is not a GRB
  29. GRB 191023A: MASTER optical observation
  30. Possible GRB 191025A: FRAM-Auger optical limit
  31. Swift Trigger 931384: possible GRB 191025A
  32. GRB 191024A: Swift-BAT refined analysis
  33. GRB 191024A: Swift/UVOT Upper Limits
  34. GRB 191024A: Afterglow Upper Limits with LCO
  35. GRB 191024A: Swift-XRT refined Analysis
  36. GRB 191024A: VLT/X-shooter optical observations
  37. GRB 191024A: GROND early upper limits
  38. GRB191024A: MASTER optical observation
  39. GRB 191024A: Enhanced Swift-XRT position
  40. GRB 191024A: Swift detection of a burst
  41. GRB 191019A: NOT optical afterglow and host association confirmation
  42. GRB 191023A: BALROG localization (Fermi Trigger 593536021 / GRB 191023630)
  43. GRB 191023A: Fermi GBM Final Real-time Localization
  44. GRB 191019A: Nanshan-0.6m optical observations
  45. GRB 191019B: AstroSat CZTI detection
  46. GRB 191022B: Fermi GBM Final Real-time Localization
  47. GRB 191022A: BALROG localization (Fermi Trigger 593419810 / GRB 191022285)
  48. GRB 191022A: Fermi GBM Final Real-time Localization
  49. Swift GRB191020.89: Global MASTER-Net OT detection
  50. GRB 191019A: Swift/UVOT Detection
  51. HAWC-191019A: Retraction of burst alert
  52. MASTER correction to GCN Circ. 26044 and 26047
  53. GCN Circ. 26044 and 26047 are mistakenly submission GRB reports
  54. HAWC-191019A: No Neutrino Counterpart detected with ANTARES
  55. GRB 191019A: Swift-XRT updated analysis
  56. Swift GRB191020.81: Global MASTER-Net OT detection
  57. GRB 191019A: Swift-BAT refined analysis
  58. GRB 191019A: Swift-XRT refined Analysis
  59. Swift GRB191019.67: Global MASTER-Net observations report
  60. GRB 191019A: Enhanced Swift-XRT position
  61. GRB 191019A: GROND observations
  62. GRB 191019A: NOT optical spectroscopy of candidate counterpart
  63. GRB 191019B: Fermi GBM Final Real-time Localization
  64. GRB 191019A: NOT optical observations
  65. Fermi trigger No 593176520: Global MASTER-Net observations report
  66. Alert from the HAWC Burst Monitor HAWC-191019A
  67. GRB 191019A: TSHAO optical observations, probable afterglow and host galaxy
  68. FACT follow-up of ANTARES-Fermi 191011A
  69. GRB 191019A: Swift-XRT observations
  70. Swift GRB191019.63: Global MASTER-Net observations report
  71. GRB 191019A: MASTER optical observation
  72. GRB 191019A: Swift detection of a burst
  73. GRB 191017B: Swift-BAT refined analysis
  74. GRB 191017B: Swift/UVOT Upper Limits
  75. GRB 191016A: REM optical observations
  76. GRB 191017B: Swift-XRT refined Analysis
  77. GRB 191016A: Swift-XRT afterglow detection
  78. Fermi trigger No 593045905: Global MASTER-Net observations report
  79. GRB 191016A: Swift/UVOT Detection
  80. GRB 191017C: Fermi GBM Final Real-time Localization
  81. GRB 191017B: Enhanced Swift-XRT position
  82. GRB 191017B: Swift detection of a burst
  83. GRB 191017A: Fermi GBM Final Localization
  84. GRB191016A: MITSuME Okayama optical observation
  85. GRB 191016A: AZT-20 (Assy observatory) optical photometry
  86. GRB 191016A: early time BOOTES Network and follow-up 1.5m OSN optical observations
  87. 191017A: BALROG localization (Fermi Trigger 592997024 / GRB 191017391)
  88. GRB 191016A: RATIR Optical and NIR Observations
  89. Baksan Neutrino Observatory Alert 191016.51: Global MASTER-Net observations report
  90. GRB 191016A: Optical limit by Ondrejov D50
  91. GRB 191016A: Swift-BAT refined analysis
  92. GRB 191016A: KAIT Optical Afterglow Confirmation
  93. GRB 191016A: COATLI Optical Observations and Detection of the Afterglow
  94. Swift GRB191016.17: Global MASTER-Net observations report
  95. GRB 191016A: Swift detection of a burst
  96. Fermi trigger No 592818648: Global MASTER-Net observations report
  97. ANTARES 191011A: MASTER optical observation befor and after trigger
  98. ANTARES 191011A: AMON + ANTARES Identification of a High-Energy Neutrino + Fermi LAT Coincidence
  99. GRB 191009A: AstroSat CZTI detection
  100. GRB 191011A: Swift-BAT refined analysis

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