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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

16281 results found.

  1. LIGO/Virgo S191213g: WHT spectroscopy of candidate counterparts
  2. LIGO/Virgo S191213g: GRAWITA TNG classification of ZTF19acykzsk
  3. LIGO/Virgo S191213g: Liverpool Telescope spectroscopy of ZTF candidates
  4. LIGO/Virgo S191205ah: AT2019wix and AT2019wib 10.4m GTC spectroscopy
  5. LIGO/Virgo S191205ah: AT2019wkv, AT2019wid and AT2019wiy 10.4m GTC spectroscopy
  6. GRB 191213A: BOOTES-5/JGT optical limit
  7. LIGO/Virgo S191205ah: AT2019wfa 10.4m GTC spectroscopy
  8. LIGO/Virgo S191205ah: MASTER OT 1.5m OSN imaging and 10.4m GTC spectroscopy
  9. LIGO/Virgo S191205ah: MITSuME Observation of MASTER OT J123123.61-043847.2
  10. LIGO/Virgo S191205ah: GMG detection of SAGUARO transient
  11. LIGO/Virgo S191205ah: SAGUARO observations and identification of an optical candidate
  12. GRB 191004A: correction to reported GROND upper limits
  13. GRB 191125B: MASTER-VWFC synchronous observation
  14. GRB 191123A: iTelescope optical upper limits
  15. GRB 191123A: Swift/UVOT detection
  16. GRB 191123A: Swift detection of a burst with an optical counterpart
  17. GRB 191122A: Swift/UVOT Upper Limits
  18. GRB 191122A: BOOTES-4/MET optical limit
  19. GRB 191122A: CHES Optical Observations
  20. LIGO/Virgo S191110af: Upper limits from KM3NeT MeV neutrino search.
  21. LIGO/Virgo S191110af: Evryscope observation report, no counterpart candidates
  22. GRB 191106A: Swift/UVOT Upper Limits
  23. GRB 191106A: NOT optical upper limit
  24. GRB 191106A: Mondy optical upper limit
  25. GRB 191106A: BOOTES-4/MET optical limit
  26. GRB 191106A: MASTER optical observation
  27. GRB191016A GROND observations
  28. Swift GRB191105.01: Global MASTER-Net OT detection
  29. GRB 191101A: Swift/UVOT Upper Limits
  30. GRB 191031D: Gemini optical upper limit
  31. GRB 191101A: iTelescope optical limit
  32. GRB 191101A: VIRT Optical Upper Limits
  33. GRB 191031D: MMT Binospec Optical Upper Limit
  34. GRB 191031D: Swift/UVOT Upper Limits
  35. GRB 191031D: MITSuME Akeno optical upper limits
  36. GRB 191031D: COATLI Optical Observations
  37. GRB 191031D: RATIR Optical and NIR Observations
  38. GRB 191031A: COATLI Optical Observations
  39. GRB 191019A: Zadko Telescope optical observations
  40. GRB 191029A: Swift/UVOT Upper Limits
  41. GRB 191028B: MASTER optical observation
  42. GRB 191029A: BOOTES-4/MET optical limit
  43. GRB 191029A: iTelescope optical upper limits
  44. GRB 191023A: MASTER optical observation
  45. Possible GRB 191025A: FRAM-Auger optical limit
  46. GRB 191024A: Swift/UVOT Upper Limits
  47. GRB 191024A: VLT/X-shooter optical observations
  48. GRB191024A: MASTER optical observation
  49. GRB 191019A: NOT optical afterglow and host association confirmation
  50. GRB 191019A: Nanshan-0.6m optical observations
  51. GCN Circ. 26044 and 26047 are mistakenly submission GRB reports
  52. Swift GRB191020.81: Global MASTER-Net OT detection
  53. GRB 191019A: NOT optical spectroscopy of candidate counterpart
  54. GRB 191019A: NOT optical observations
  55. GRB 191019A: TSHAO optical observations, probable afterglow and host galaxy
  56. GRB 191019A: MASTER optical observation
  57. GRB 191017B: Swift/UVOT Upper Limits
  58. GRB 191016A: REM optical observations
  59. GRB 191016A: Swift/UVOT Detection
  60. GRB191016A: MITSuME Okayama optical observation
  61. GRB 191016A: AZT-20 (Assy observatory) optical photometry
  62. GRB 191016A: early time BOOTES Network and follow-up 1.5m OSN optical observations
  63. GRB 191016A: RATIR Optical and NIR Observations
  64. GRB 191016A: Optical limit by Ondrejov D50
  65. GRB 191016A: KAIT Optical Afterglow Confirmation
  66. GRB 191016A: COATLI Optical Observations and Detection of the Afterglow
  67. ANTARES 191011A: MASTER optical observation befor and after trigger
  68. GRB 191011A: Swift/UVOT Detection
  69. GRB 191011A: RATIR Optical and NIR Observations
  70. GRB 19011A: Optical Afterglow Detection with LCO
  71. GRB 191011A: MASTER OT retraction.
  72. GRB 191011A: GROND Detection of the Optical/NIR afterglow
  73. GRB 191011A: VLT X-shooter redshift from RRM Observations
  74. Swift GRB191011.19: Global MASTER-Net OT detection
  75. GRB 191011A: Swift detection of a burst with an optical counterpart
  76. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  77. TESS Detection of the Optical Emission from the Possible Untriggered GRB Associated with ZTF19abvizsw
  78. GRB 191004B: Continued Optical Afterglow Monitoring with LCO
  79. GRB 191004A: Optical Detection with LCO
  80. GRB 190928A: AstroSat CZTI detection
  81. LIGO/Virgo S190930t: Swift J221951-484240 optical photometry of Chilescope observatory
  82. LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240
  83. GRB 191004B: GROND Detection of the Optical/NIR Afterglow
  84. GRB 191004B: COATLI Optical Observations
  85. GRB 191004B: VLT/X-shooter redshift
  86. GRB 191004B: NOT optical photometry
  87. GRB 191004A: NOT optical upper limits
  88. GRB 191004B: Optical Afterglow Detection with LCO
  89. Swift GRB191004.9: Global MASTER-Net OT detection
  90. GRB 191004B: Swift detection of a burst with an optical counterpart
  91. GRB 191004A: Swift detection of a burst with an optical detection
  92. Swift GRB191004.75: Global MASTER-Net OT detection
  93. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO continued optical photometry
  94. GRB 191001A: Swift-XRT observations
  95. LIGO/Virgo S190930t: J-GEM follow-up observation for Swift J221951-484240
  96. GRB 191001B: Optical Upper Limits with LCO
  97. LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
  98. GRB 191001A: Fermi GBM observation
  99. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO optical photometry
  100. IPN triangulation of GRB 191001A

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