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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. VLA observations of GW170817 at ~4.8 years after the merger
  2. Fermi GRB 220523A: Global MASTER-Net observations report
  3. GRB 220523A: Fermi GBM Final Real-time Localization
  4. GRB 220521A: LCO Optical Detection
  5. GRB 220521A: Swift-BAT refined analysis
  6. GRB 220521A: Fermi GBM detection
  7. GRB 220521A: Sintesz-Newton/CrAO optical upper limit
  8. GRB 220521A: RATIR Optical and NIR Observations
  9. GRB 220521A: Swift-XRT refined Analysis
  10. GRB 220521A: Swift/UVOT Upper Limits
  11. Fermi GRB 220522A: Global MASTER-Net observations report
  12. Fermi trigger No 674868783: Global MASTER-Net observations report
  13. GRB 220521A: SAO RAS optical observations
  14. GRB 220521A: Enhanced Swift-XRT position
  15. GRB 220522A: Fermi GBM Final Real-time Localization
  16. GRB 220521A: NOT spectroscopic redshift
  17. GRB 220521A: NOT optical afterglow detection
  18. GRB 220521A: Prompt enhanced Swift-XRT position
  19. GRB 220521A: Swift detection of a burst
  20. GRB 220521A: Fermi GBM Final Real-time Localization
  21. Swift GRB220521.97: Global MASTER-Net observations report
  22. Konus-Wind detection of GRB 220519A
  23. IPN triangulation of GRB 220519A
  24. Swift BAT Trigger 1107209 is not an astrophysical event
  25. GRB 220514A: AstroSat CZTI detection
  26. GRB 220518A: Swift-BAT refined analysis
  27. Swift GRB220519.84: Global MASTER-Net observations report
  28. GRB 220518A: Swift-XRT refined Analysis
  29. Fermi GRB 220518B: Global MASTER-Net observations report
  30. Continued Chandra monitoring of GW170817 at ~4.8 yr post-merger
  31. GRB 220518B: Fermi GBM Final Real-time Localization
  32. GRB 220518A: Swift/UVOT Detection
  33. GRB 220518A: Enhanced Swift-XRT position
  34. Swift GRB 220518A: Global MASTER-Net observations report
  35. GRB 220518A: Swift detection of a burst
  36. GRB 220514A: MITSuME Akeno optical observation
  37. GRB 220514A: GRANDMA Optical Afterglow Observations
  38. Konus-Wind detection of GRB 220506A
  39. Konus-Wind detection of GRB 220514B
  40. Fermi trigger No 674397342: Global MASTER-Net observations report
  41. GRB 220514A: Fermi GBM observation
  42. GRB 220514B: Swift-XRT observations
  43. GRB 220511A: Swift-XRT afterglow detection
  44. GRB 220514A: KAIT Optical Afterglow Confirmation
  45. Fermi-LAT Gamma-ray Observations of IceCube-220513A
  46. IceCube-220513A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 220514B: Tiled Swift observations
  48. [SUBJECT]: IceCube-220513A: No significant detection in HAWC
  49. GRB 220514B: MAXI/GSC detection
  50. MAXI GRB220514.98: Global MASTER-Net observations report
  51. GRB 220514A: MeerLICHT optical afterglow candidate
  52. Integral GRB220514.52: Global MASTER-Net observations report
  53. Fermi GRB 220514A: Global MASTER-Net observations report
  54. GRB 220514A: a long GRB detected by INTEGRAL
  55. IceCube-220513A: No Candidate Counterparts from the Zwicky Transient Facility
  56. GRB 220514A: BALROG localization (Fermi Trigger 674223877 / GRB 220514517)
  57. GRB 220514A: Fermi GBM Final Real-time Localization
  58. IceCube-220513A - IceCube observation of a high-energy neutrino candidate track-like event
  59. IceCube Alert 220513.97: Global MASTER-Net observations report
  60. Fermi GRB 220513A: Global MASTER-Net observations report
  61. GRB 220513A: Fermi GBM Final Real-time Localization
  62. Konus-Wind detection of GRB 220511A
  63. GRB 220427A: MeerLICHT afterglow observations
  64. IceCube-220509A: No significant detection in HAWC
  65. GRB 220511A: Fermi GBM observation
  66. GRB 220511A: Swift-XRT observations
  67. GRB 220511A: AstroSat CZTI detection
  68. GRB 220511A: BOOTES-2/TELMA optical upper limit
  69. Fermi GRB 220512A: Global MASTER-Net observations report
  70. GRB 220512A: Fermi GBM Final Real-time Localization
  71. GRB 220511A: Swift ToO observations
  72. GRB 220511A: Swift/BAT-GUANO arcminute localization
  73. Fermi GRB 220511A: Global MASTER-Net observations report
  74. GRB 220511A: AGILE detection
  75. IceCube-220509A: Upper limits from a search for additional neutrino events in IceCube
  76. GRB 220511A: BALROG localization (Fermi Trigger 673969321/ GRB 220511571)
  77. GRB 220511A: Fermi GBM Final Real-time Localization
  78. GRB 220507A: AstroSat CZTI detection
  79. Fermi-LAT Gamma-ray Observations of IceCube-220509A
  80. Fermi trigger No 673846271: Global MASTER-Net observations report
  81. GRB 220506A: MITSuME Akeno optical upper limits
  82. IceCube-220509A - IceCube observation of a high-energy neutrino candidate track-like event
  83. GRB 220506A: GIT optical upper limit.
  84. IceCube Alert 220509.76: Global MASTER-Net observations report
  85. GRB 220508A: Fermi GBM Final Real-time Localization
  86. GRB 220507A: Fermi GBM Final Localization
  87. GRB 220506A: BOOTES-5/JGT optical upper limit
  88. Fermi trigger No 673610950: Global MASTER-Net observations report
  89. GRB 220506A: Swift-XRT afterglow detection
  90. GRB 220506A: Tiled Swift observations
  91. IceCube-220405B - ZTF19aavnpjv unrelated
  92. Swift-BAT triggers 1105560-1 are not GRBs
  93. Swift GRB220506.51: Global MASTER-Net observations report
  94. GRB 220506A/MAXI J1558-266: MAXI/GSC detection
  95. MAXI GRB220506.27: Global MASTER-Net observations report
  96. GRB 220430A: Nanshan/NEXT optical upper limit
  97. GRB 220430A: Nanshan/HMT optical upper limit
  98. GRB 220430A: GIT optical upper limits
  99. IPN triangulation of GRB 220423A
  100. GRB 220427A: LCO Optical Observations

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