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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"

28044 results found.

  1. GRB 191031C: Swift-BAT refined analysis
  2. GRB 191031A: Swift-BAT refined analysis
  3. GRB 191031C: Swift-XRT refined Analysis
  4. GRB 191031D: Swift/UVOT Upper Limits
  5. GRB 191031C: Swift/UVOT Detection
  6. GRB 191031D: Swift-XRT refined Analysis
  7. GRB 191031D: COATLI Optical Observations
  8. GRB 191031D: RATIR Optical and NIR Observations
  9. GRB 191031D: VLA 9.8 GHz upper limit
  10. GRB 191031C: Fermi GBM detection
  11. GRB 191031D: Enhanced Swift-XRT position
  12. GRB 191031A: Fermi GBM detection
  13. GRB 191031C: Enhanced Swift-XRT position
  14. GRB 191031D: Swift detection of a short hard burst
  15. GRB 191029A: Swift-BAT refined analysis
  16. GRB 191031C: Swift detection of a burst
  17. GRB 191031A: COATLI Optical Observations
  18. GRB 191029A: CORRECTED Swift-XRT refined analysis
  19. GRB 191029A: Swift/UVOT Upper Limits
  20. GRB 191029A: Enhanced Swift-XRT position
  21. GRB 191029A: Swift-XRT refined Analysis
  22. GRB 191029A: BOOTES-4/MET optical limit
  23. GRB 191029A: iTelescope optical upper limits
  24. GRB 191029A: Swift-XRT observations
  25. IPN triangulation of GRB 191027A
  26. GRB 191028B: BALROG localization (Fermi Trigger 593964489 / GRB 191028589)
  27. GRB 191025B: Insight-HXMT/HE detection
  28. GRB 191027A: BALROG localization (Fermi Trigger 593882352 / GRB 191027638)
  29. Swift Trigger 931484 is not a GRB
  30. GRB 191023A: MASTER optical observation
  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. GRB 191024A: Enhanced Swift-XRT position
  39. GRB 191024A: Swift detection of a burst
  40. GRB 191023A: BALROG localization (Fermi Trigger 593536021 / GRB 191023630)
  41. GRB 191019A: Nanshan-0.6m optical observations
  42. GRB 191022A: BALROG localization (Fermi Trigger 593419810 / GRB 191022285)
  43. GRB 191019A: Swift/UVOT Detection
  44. HAWC-191019A: No Neutrino Counterpart detected with ANTARES
  45. GRB 191019A: Swift-XRT updated analysis
  46. Swift GRB191020.81: Global MASTER-Net OT detection
  47. GRB 191019A: Swift-BAT refined analysis
  48. GRB 191019A: Enhanced Swift-XRT position
  49. GRB 191019A: GROND observations
  50. GRB 191019A: NOT optical observations
  51. Alert from the HAWC Burst Monitor HAWC-191019A
  52. GRB 191019A: TSHAO optical observations, probable afterglow and host galaxy
  53. GRB 191019A: Swift-XRT observations
  54. GRB 191017B: Swift-BAT refined analysis
  55. GRB 191017B: Swift/UVOT Upper Limits
  56. GRB 191016A: REM optical observations
  57. GRB 191017B: Swift-XRT refined Analysis
  58. GRB 191016A: Swift-XRT afterglow detection
  59. GRB 191016A: Swift/UVOT Detection
  60. GRB 191017B: Enhanced Swift-XRT position
  61. GRB 191017B: Swift detection of a burst
  62. GRB 191016A: AZT-20 (Assy observatory) optical photometry
  63. GRB 191016A: early time BOOTES Network and follow-up 1.5m OSN optical observations
  64. 191017A: BALROG localization (Fermi Trigger 592997024 / GRB 191017391)
  65. GRB 191016A: RATIR Optical and NIR Observations
  66. GRB 191016A: Swift-BAT refined analysis
  67. GRB 191016A: COATLI Optical Observations and Detection of the Afterglow
  68. GRB 191016A: Swift detection of a burst
  69. ANTARES 191011A: MASTER optical observation befor and after trigger
  70. ANTARES 191011A: AMON + ANTARES Identification of a High-Energy Neutrino + Fermi LAT Coincidence
  71. GRB 191011A: Swift-BAT refined analysis
  72. GRB 191011A: Swift/UVOT Detection
  73. GRB 191011A: RATIR Optical and NIR Observations
  74. GRB 191011A: Fermi GBM observation
  75. GRB 19011A: Optical Afterglow Detection with LCO
  76. GRB 191011A: Swift-XRT refined Analysis
  77. GRB 191009A: Insight-HXMT/HE detection
  78. GRB 191011A: Enhanced Swift-XRT position
  79. GRB 191011A: correction of reported magnitudes
  80. GRB 191011A: BALROG localization (Fermi Trigger 592461363 / GRB 191011192)
  81. GRB 191011A: GROND Detection of the Optical/NIR afterglow
  82. GRB 191011A: VLT X-shooter redshift from RRM Observations
  83. Swift GRB191011.19: Global MASTER-Net OT detection
  84. GRB 191011A: Swift detection of a burst with an optical counterpart
  85. GRB 191009A: BALROG localization (Fermi Trigger 592297741 / GRB 191009298)
  86. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  87. GRB 191004B: Swift/UVOT Detection
  88. GRB 191004B: Continued Optical Afterglow Monitoring with LCO
  89. Konus-Wind observation of GRB 191004B
  90. Konus-Wind observation of GRB 191004A
  91. GRB 191004A: Swift/UVOT Detection
  92. GRB 191004A: Optical Detection with LCO
  93. LIGO/Virgo S190930s: no counterpart candidate in the SVOM/GWAC observations
  94. LIGO/Virgo S190930s: Updated Sky Localization
  95. LIGO/Virgo S190930t: Swift XRT observations, no secure afterglow found
  96. LIGO/Virgo S190930t: Swift discovery of Swift J224718-581442 (AT2019sbk): a fading UV transient with an X-ray counterpart
  97. LIGO/Virgo S190930t: Swift J221951-484240 optical photometry of Chilescope observatory
  98. LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240
  99. GRB 191004B: Swift-XRT refined Analysis
  100. GRB 191004B: GROND Detection of the Optical/NIR Afterglow

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