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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 931484 is not a GRB
  2. GRB 191023A: MASTER optical observation
  3. Possible GRB 191025A: FRAM-Auger optical limit
  4. Swift Trigger 931384: possible GRB 191025A
  5. GRB 191024A: Swift-BAT refined analysis
  6. GRB 191024A: Swift/UVOT Upper Limits
  7. GRB 191024A: Afterglow Upper Limits with LCO
  8. GRB 191024A: Swift-XRT refined Analysis
  9. GRB 191024A: VLT/X-shooter optical observations
  10. GRB 191024A: GROND early upper limits
  11. GRB191024A: MASTER optical observation
  12. GRB 191024A: Enhanced Swift-XRT position
  13. GRB 191024A: Swift detection of a burst
  14. GRB 191019A: NOT optical afterglow and host association confirmation
  15. GRB 191023A: BALROG localization (Fermi Trigger 593536021 / GRB 191023630)
  16. GRB 191023A: Fermi GBM Final Real-time Localization
  17. GRB 191019A: Nanshan-0.6m optical observations
  18. GRB 191019B: AstroSat CZTI detection
  19. GRB 191022B: Fermi GBM Final Real-time Localization
  20. GRB 191022A: BALROG localization (Fermi Trigger 593419810 / GRB 191022285)
  21. GRB 191022A: Fermi GBM Final Real-time Localization
  22. Swift GRB191020.89: Global MASTER-Net OT detection
  23. GRB 191019A: Swift/UVOT Detection
  24. HAWC-191019A: Retraction of burst alert
  25. MASTER correction to GCN Circ. 26044 and 26047
  26. GCN Circ. 26044 and 26047 are mistakenly submission GRB reports
  27. HAWC-191019A: No Neutrino Counterpart detected with ANTARES
  28. GRB 191019A: Swift-XRT updated analysis
  29. Swift GRB191020.81: Global MASTER-Net OT detection
  30. GRB 191019A: Swift-BAT refined analysis
  31. GRB 191019A: Swift-XRT refined Analysis
  32. Swift GRB191019.67: Global MASTER-Net observations report
  33. GRB 191019A: Enhanced Swift-XRT position
  34. GRB 191019A: GROND observations
  35. GRB 191019A: NOT optical spectroscopy of candidate counterpart
  36. GRB 191019B: Fermi GBM Final Real-time Localization
  37. GRB 191019A: NOT optical observations
  38. Fermi trigger No 593176520: Global MASTER-Net observations report
  39. Alert from the HAWC Burst Monitor HAWC-191019A
  40. GRB 191019A: TSHAO optical observations, probable afterglow and host galaxy
  41. FACT follow-up of ANTARES-Fermi 191011A
  42. GRB 191019A: Swift-XRT observations
  43. Swift GRB191019.63: Global MASTER-Net observations report
  44. GRB 191019A: MASTER optical observation
  45. GRB 191019A: Swift detection of a burst
  46. GRB 191017B: Swift-BAT refined analysis
  47. GRB 191017B: Swift/UVOT Upper Limits
  48. GRB 191016A: REM optical observations
  49. GRB 191017B: Swift-XRT refined Analysis
  50. GRB 191016A: Swift-XRT afterglow detection
  51. Fermi trigger No 593045905: Global MASTER-Net observations report
  52. GRB 191016A: Swift/UVOT Detection
  53. GRB 191017C: Fermi GBM Final Real-time Localization
  54. GRB 191017B: Enhanced Swift-XRT position
  55. GRB 191017B: Swift detection of a burst
  56. GRB 191017A: Fermi GBM Final Localization
  57. GRB191016A: MITSuME Okayama optical observation
  58. GRB 191016A: AZT-20 (Assy observatory) optical photometry
  59. GRB 191016A: early time BOOTES Network and follow-up 1.5m OSN optical observations
  60. 191017A: BALROG localization (Fermi Trigger 592997024 / GRB 191017391)
  61. GRB 191016A: RATIR Optical and NIR Observations
  62. Baksan Neutrino Observatory Alert 191016.51: Global MASTER-Net observations report
  63. GRB 191016A: Optical limit by Ondrejov D50
  64. GRB 191016A: Swift-BAT refined analysis
  65. GRB 191016A: KAIT Optical Afterglow Confirmation
  66. GRB 191016A: COATLI Optical Observations and Detection of the Afterglow
  67. Swift GRB191016.17: Global MASTER-Net observations report
  68. GRB 191016A: Swift detection of a burst
  69. Fermi trigger No 592818648: Global MASTER-Net observations report
  70. ANTARES 191011A: MASTER optical observation befor and after trigger
  71. ANTARES 191011A: AMON + ANTARES Identification of a High-Energy Neutrino + Fermi LAT Coincidence
  72. GRB 191009A: AstroSat CZTI detection
  73. GRB 191011A: Swift-BAT refined analysis
  74. GRB 191011A: Swift/UVOT Detection
  75. GRB 191011A: RATIR Optical and NIR Observations
  76. GRB 191011A: Fermi GBM observation
  77. GRB 19011A: Optical Afterglow Detection with LCO
  78. GRB 191011A: Swift-XRT refined Analysis
  79. GRB 191009A: Insight-HXMT/HE detection
  80. GRB 191011A: MASTER OT retraction.
  81. GRB 191011A: Enhanced Swift-XRT position
  82. GRB 191011A: correction of reported magnitudes
  83. GRB 191011A: BALROG localization (Fermi Trigger 592461363 / GRB 191011192)
  84. GRB 191011A: GROND Detection of the Optical/NIR afterglow
  85. GRB 191011A: VLT X-shooter redshift from RRM Observations
  86. Swift GRB191011.19: Global MASTER-Net observations report
  87. Swift GRB191011.19: Global MASTER-Net OT detection
  88. GRB 191011A: Swift detection of a burst with an optical counterpart
  89. GRB 191011A: Fermi GBM Final Real-time Localization
  90. GRB 191009A: BALROG localization (Fermi Trigger 592297741 / GRB 191009298)
  91. GRB 191009A: Fermi GBM Final Real-time Localization
  92. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  93. Fermi trigger No 592211224: Global MASTER-Net observations report
  94. TESS Detection of the Optical Emission from the Possible Untriggered GRB Associated with ZTF19abvizsw
  95. GRB 191004A: CALET Gamma-Ray Burst Monitor detection
  96. Fermi trigger No 592211224: Global MASTER-Net observations report
  97. GRB 191008A: Fermi GBM Final Real-time Localization
  98. GRB 191004B: Swift/UVOT Detection
  99. GRB 191004B: Continued Optical Afterglow Monitoring with LCO
  100. GRB 191004B: Correction to Konus-Wind GCN 25974

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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