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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 191016A: RATIR Optical and NIR Observations
  2. Baksan Neutrino Observatory Alert 191016.51: Global MASTER-Net observations report
  3. GRB 191016A: Optical limit by Ondrejov D50
  4. GRB 191016A: Swift-BAT refined analysis
  5. GRB 191016A: KAIT Optical Afterglow Confirmation
  6. GRB 191016A: COATLI Optical Observations and Detection of the Afterglow
  7. Swift GRB191016.17: Global MASTER-Net observations report
  8. GRB 191016A: Swift detection of a burst
  9. Fermi trigger No 592818648: Global MASTER-Net observations report
  10. ANTARES 191011A: MASTER optical observation befor and after trigger
  11. ANTARES 191011A: AMON + ANTARES Identification of a High-Energy Neutrino + Fermi LAT Coincidence
  12. GRB 191009A: AstroSat CZTI detection
  13. GRB 191011A: Swift-BAT refined analysis
  14. GRB 191011A: Swift/UVOT Detection
  15. GRB 191011A: RATIR Optical and NIR Observations
  16. GRB 191011A: Fermi GBM observation
  17. GRB 19011A: Optical Afterglow Detection with LCO
  18. GRB 191011A: Swift-XRT refined Analysis
  19. GRB 191009A: Insight-HXMT/HE detection
  20. GRB 191011A: MASTER OT retraction.
  21. GRB 191011A: Enhanced Swift-XRT position
  22. GRB 191011A: correction of reported magnitudes
  23. GRB 191011A: BALROG localization (Fermi Trigger 592461363 / GRB 191011192)
  24. GRB 191011A: GROND Detection of the Optical/NIR afterglow
  25. GRB 191011A: VLT X-shooter redshift from RRM Observations
  26. Swift GRB191011.19: Global MASTER-Net observations report
  27. Swift GRB191011.19: Global MASTER-Net OT detection
  28. GRB 191011A: Swift detection of a burst with an optical counterpart
  29. GRB 191011A: Fermi GBM Final Real-time Localization
  30. GRB 191009A: BALROG localization (Fermi Trigger 592297741 / GRB 191009298)
  31. GRB 191009A: Fermi GBM Final Real-time Localization
  32. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  33. Fermi trigger No 592211224: Global MASTER-Net observations report
  34. TESS Detection of the Optical Emission from the Possible Untriggered GRB Associated with ZTF19abvizsw
  35. GRB 191004A: CALET Gamma-Ray Burst Monitor detection
  36. Fermi trigger No 592211224: Global MASTER-Net observations report
  37. GRB 191008A: Fermi GBM Final Real-time Localization
  38. GRB 191004B: Swift/UVOT Detection
  39. GRB 191004B: Continued Optical Afterglow Monitoring with LCO
  40. GRB 191004B: Correction to Konus-Wind GCN 25974
  41. Fermi/GBM observation of a bright burst from magnetar SGR 1935+2154
  42. Konus-Wind observation of GRB 191004B
  43. Konus-Wind observation of GRB 191004A
  44. GRB 191004A: Swift/UVOT Detection
  45. GRB 191004A: Optical Detection with LCO
  46. LIGO/Virgo S190930s: no counterpart candidate in the SVOM/GWAC observations
  47. LIGO/Virgo S190930s: Updated Sky Localization
  48. LIGO/Virgo S190930t: Magellan/IMACS imaging of Swift J224718-581442 (AT2019sbk)
  49. LIGO/Virgo S190930t: Swift XRT observations, no secure afterglow found
  50. GRB 190928A: AstroSat CZTI detection
  51. LIGO/Virgo S190930t: Swift discovery of Swift J224718-581442 (AT2019sbk): a fading UV transient with an X-ray counterpart
  52. LIGO/Virgo S190930t: Swift J221951-484240 optical photometry of Chilescope observatory
  53. LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240
  54. GRB 191004B: Swift-XRT refined Analysis
  55. GRB 191004B: GROND Detection of the Optical/NIR Afterglow
  56. GRB 191004A: GROND Upper limits
  57. GRB 191004B: COATLI Optical Observations
  58. GRB 191004A: Swift-XRT refined Analysis
  59. GRB 191004B: VLT/X-shooter redshift
  60. GRB 191004B: Swift-BAT refined analysis
  61. GRB 191004B: NOT optical photometry
  62. GRB 191004A: Swift-BAT refined analysis
  63. GRB 191004A: NOT optical upper limits
  64. GRB 191004B: Enhanced Swift-XRT position
  65. GRB 191004A: Enhanced Swift-XRT position
  66. GRB 191004B: Optical Afterglow Detection with LCO
  67. Swift GRB191004.9: Global MASTER-Net OT detection
  68. GRB 191004B: Swift detection of a burst with an optical counterpart
  69. FACT follow-up of IceCube-191001A
  70. GRB 191004A: Swift detection of a burst with an optical detection
  71. Swift GRB191004.75: Global MASTER-Net OT detection
  72. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO continued optical photometry
  73. GRB 191001A: Swift-XRT observations
  74. LIGO/Virgo S190930t: J-GEM follow-up observation for Swift J221951-484240
  75. GRB 191001B: Optical Upper Limits with LCO
  76. LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
  77. GRB 191001A: Fermi GBM observation
  78. GRB 190926A: Upper limit from CAHA 2.2m observation
  79. IceCube-191001A: HAWC follow-up
  80. GRB 190919A: AstroSat CZTI detection
  81. LIGO/Virgo S190930t: Upper limits from Insight-HXMT/HE observations
  82. LIGO/Virgo S190930s: Upper limits from Insight-HXMT/HE observations
  83. Fermi-LAT Gamma-ray Observations of IceCube-191001A
  84. LIGO/Virgo S190930t: Palomar 200-in DBSP spectroscopy of ZTF19acbwaah
  85. GRB 191001B: Swift-BAT refined analysis
  86. IceCube-191001A: Candidate Counterparts with the Zwicky Transient Facility
  87. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO optical photometry
  88. IceCube-191001A: Not observable by Fermi-GBM
  89. IPN triangulation of GRB 191001A
  90. LIGO/Virgo S190930t: No neutrino candidates at Pierre Auger Observatory
  91. GRB 191001A: Swift ToO observations
  92. LIGO/Virgo S190930t: ATLAS Forced photometry of ZTF19acbpqlh (AT2019rpn)
  93. LIGO/Virgo S190930t: Candidates from ATLAS observations and constraints on AT2019rpr and AT2019rpn
  94. LIGO/Virgo S190930t: Palomar 200-in DBSP follow-up of ZTF19acbpqlh and ATLAS19wyn
  95. LIGO/Virgo S190930t: J-GEM follow-up observations for AT2019rpj
  96. GRB 191001A: KAIT Optical Upper Limit
  97. GRB 191001A: RATIR Optical and NIR Observations
  98. LIGO/Virgo S190930t: HCT observations of ZTF19acbpsuf
  99. LIGO/Virgo S190930t: Lulin Follow-up Observations of AT2019rpn and AT2019rpj
  100. LIGO/Virgo S190930s: no counterpart candidates in SAGUARO/CSS observations

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