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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"

28050 results found.

  1. GRB 191101A: Enhanced Swift-XRT position
  2. Fermi trigger No 594227699: Global MASTER-Net observations report
  3. GRB 191101B: Fermi GBM Final Real-time Localization
  4. GRB 191101A: Swift detection of a burst
  5. GRB 191031D: MMT Binospec Optical Upper Limit
  6. GRB 191031D: Swift-BAT refined analysis
  7. GRB 191031C: Swift-BAT refined analysis
  8. GRB 191031A: Swift-BAT refined analysis
  9. GRB 191031C: Swift-XRT refined Analysis
  10. GRB 191031D: Swift/UVOT Upper Limits
  11. GRB 191031C: Swift/UVOT Detection
  12. GRB 191031D: Swift-XRT refined Analysis
  13. GRB 191031D: COATLI Optical Observations
  14. GRB 191031D: RATIR Optical and NIR Observations
  15. GRB 191031D: VLA 9.8 GHz upper limit
  16. GRB 191031C: Fermi GBM detection
  17. GRB 191031D: Enhanced Swift-XRT position
  18. GRB 191031A: Fermi GBM detection
  19. GRB 191031C: Enhanced Swift-XRT position
  20. GRB 191031D: Swift detection of a short hard burst
  21. GRB 191029A: Swift-BAT refined analysis
  22. GRB 191031C: Swift detection of a burst
  23. GRB 191031A: COATLI Optical Observations
  24. GRB 191029A: CORRECTED Swift-XRT refined analysis
  25. GRB 191029A: Swift/UVOT Upper Limits
  26. GRB 191029A: Enhanced Swift-XRT position
  27. GRB 191029A: Swift-XRT refined Analysis
  28. GRB 191029A: BOOTES-4/MET optical limit
  29. GRB 191029A: iTelescope optical upper limits
  30. GRB 191029A: Swift-XRT observations
  31. IPN triangulation of GRB 191027A
  32. GRB 191028B: BALROG localization (Fermi Trigger 593964489 / GRB 191028589)
  33. GRB 191025B: Insight-HXMT/HE detection
  34. GRB 191027A: BALROG localization (Fermi Trigger 593882352 / GRB 191027638)
  35. Swift Trigger 931484 is not a GRB
  36. GRB 191023A: MASTER optical observation
  37. Swift Trigger 931384: possible GRB 191025A
  38. GRB 191024A: Swift-BAT refined analysis
  39. GRB 191024A: Swift/UVOT Upper Limits
  40. GRB 191024A: Afterglow Upper Limits with LCO
  41. GRB 191024A: Swift-XRT refined Analysis
  42. GRB 191024A: VLT/X-shooter optical observations
  43. GRB 191024A: GROND early upper limits
  44. GRB 191024A: Enhanced Swift-XRT position
  45. GRB 191024A: Swift detection of a burst
  46. GRB 191023A: BALROG localization (Fermi Trigger 593536021 / GRB 191023630)
  47. GRB 191019A: Nanshan-0.6m optical observations
  48. GRB 191022A: BALROG localization (Fermi Trigger 593419810 / GRB 191022285)
  49. GRB 191019A: Swift/UVOT Detection
  50. HAWC-191019A: No Neutrino Counterpart detected with ANTARES
  51. GRB 191019A: Swift-XRT updated analysis
  52. Swift GRB191020.81: Global MASTER-Net OT detection
  53. GRB 191019A: Swift-BAT refined analysis
  54. GRB 191019A: Enhanced Swift-XRT position
  55. GRB 191019A: GROND observations
  56. GRB 191019A: NOT optical observations
  57. Alert from the HAWC Burst Monitor HAWC-191019A
  58. GRB 191019A: TSHAO optical observations, probable afterglow and host galaxy
  59. GRB 191019A: Swift-XRT observations
  60. GRB 191017B: Swift-BAT refined analysis
  61. GRB 191017B: Swift/UVOT Upper Limits
  62. GRB 191016A: REM optical observations
  63. GRB 191017B: Swift-XRT refined Analysis
  64. GRB 191016A: Swift-XRT afterglow detection
  65. GRB 191016A: Swift/UVOT Detection
  66. GRB 191017B: Enhanced Swift-XRT position
  67. GRB 191017B: Swift detection of a burst
  68. GRB 191016A: AZT-20 (Assy observatory) optical photometry
  69. GRB 191016A: early time BOOTES Network and follow-up 1.5m OSN optical observations
  70. 191017A: BALROG localization (Fermi Trigger 592997024 / GRB 191017391)
  71. GRB 191016A: RATIR Optical and NIR Observations
  72. GRB 191016A: Swift-BAT refined analysis
  73. GRB 191016A: COATLI Optical Observations and Detection of the Afterglow
  74. GRB 191016A: Swift detection of a burst
  75. ANTARES 191011A: MASTER optical observation befor and after trigger
  76. ANTARES 191011A: AMON + ANTARES Identification of a High-Energy Neutrino + Fermi LAT Coincidence
  77. GRB 191011A: Swift-BAT refined analysis
  78. GRB 191011A: Swift/UVOT Detection
  79. GRB 191011A: RATIR Optical and NIR Observations
  80. GRB 191011A: Fermi GBM observation
  81. GRB 19011A: Optical Afterglow Detection with LCO
  82. GRB 191011A: Swift-XRT refined Analysis
  83. GRB 191009A: Insight-HXMT/HE detection
  84. GRB 191011A: Enhanced Swift-XRT position
  85. GRB 191011A: correction of reported magnitudes
  86. GRB 191011A: BALROG localization (Fermi Trigger 592461363 / GRB 191011192)
  87. GRB 191011A: GROND Detection of the Optical/NIR afterglow
  88. GRB 191011A: VLT X-shooter redshift from RRM Observations
  89. Swift GRB191011.19: Global MASTER-Net OT detection
  90. GRB 191011A: Swift detection of a burst with an optical counterpart
  91. GRB 191009A: BALROG localization (Fermi Trigger 592297741 / GRB 191009298)
  92. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  93. GRB 191004B: Swift/UVOT Detection
  94. GRB 191004B: Continued Optical Afterglow Monitoring with LCO
  95. Konus-Wind observation of GRB 191004B
  96. Konus-Wind observation of GRB 191004A
  97. GRB 191004A: Swift/UVOT Detection
  98. GRB 191004A: Optical Detection with LCO
  99. LIGO/Virgo S190930s: no counterpart candidate in the SVOM/GWAC observations
  100. LIGO/Virgo S190930s: Updated Sky Localization

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