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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"

2722 results found.

  1. Fermi GRB 211024A: Global MASTER-Net observations report
  2. GRB 211022A: GECAM detection
  3. GRB 211019A: Fermi GBM Final Real-time Localization
  4. Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
  5. Fermi trigger No 655646385: Global MASTER-Net observations report
  6. Swift GRB211001.03: Global MASTER-Net observations report
  7. Fermi trigger No 654658271: Global MASTER-Net observations report
  8. Fermi GRB 210929B: Global MASTER-Net observations report
  9. GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
  10. GRB 210919A: iTelescope T-11 upper limits
  11. IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
  12. IceCube Alert 210922.76: Global MASTER-Net observations report
  13. Swift GRB 210919A: Global MASTER-Net observations report
  14. GRB 210917A: Fermi GBM Final Real-time Localization
  15. AGILE observations of two bright bursts from SGR 1935+2154
  16. Fermi trigger No 653083551: Global MASTER-Net observations report
  17. Fermi trigger No 653066130: Global MASTER-Net observations report
  18. Fermi trigger No 653049776: Global MASTER-Net observations report
  19. Fermi trigger No 653010039: Global MASTER-Net observations report
  20. IPN triangulation of a bright burst from SGR 1935+2154
  21. Fermi trigger No 652927551: Global MASTER-Net observations report
  22. Fermi trigger No 652911693: Global MASTER-Net observations report
  23. Fermi trigger No 652906639: Global MASTER-Net observations report
  24. Fermi GRB 210909A: Global MASTER-Net observations report
  25. Fermi trigger No 652585475: Global MASTER-Net observations report
  26. GRB 210905A: Swift detection of a burst
  27. GRB 210904A: Fermi GBM Final Real-time Localization
  28. Fermi GRB 210903A: Global MASTER-Net observations report
  29. Fermi GRB 210827A: Global MASTER-Net observations report
  30. GRB 210827A: Swift/BAT-GUANO detection and arcminute localization
  31. GRB 210826A: Swift-XRT observations
  32. GRB 210822A: TSHAO continued optical observation
  33. GRB 210822A: TSHAO optical observation
  34. Swift GRB 210824A: Global MASTER-Net observations report
  35. Fermi trigger No 651306769: Global MASTER-Net observations report
  36. Fermi GRB 210822B: Global MASTER-Net observations report
  37. Konus-Wind detection of GRB 210818A
  38. GRB 210812A is consistent with being a lensed GRB
  39. IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
  40. Fermi GRB 210813A: Global MASTER-Net observations report
  41. GRB 210812A: BALROG localization (Fermi Trigger 650479626 / GRB 210812699)
  42. GRB 210812A: Fermi GBM Final Real-time Localization
  43. Fermi GRB 210807C: Global MASTER-Net observations report
  44. Fermi GRB 210807B: Global MASTER-Net observations report
  45. Swift GRB210731.62: Global MASTER-Net observations report
  46. GRB 210731A: MeerLICHT optical afterglow detection
  47. Trigger 1062273: Swift detection of 4U 1700-377
  48. IPN triangulation of GRB 210727A (short)
  49. Fermi trigger No 648959581: Global MASTER-Net observations report
  50. GRB 210725A: Fermi GBM detection
  51. GRB 210725A: CALET Gamma-Ray Burst Monitor detection
  52. Fermi trigger No 648868114: Global MASTER-Net observations report
  53. GRB 210725A: Swift detection of a burst
  54. GRB 210723A: Swift detection of a burst
  55. Fermi trigger No 648602917: Global MASTER-Net observations report
  56. Fermi trigger No 648278666: Global MASTER-Net observations report
  57. Fermi trigger No 647942198: Global MASTER-Net observations report
  58. Fermi trigger No 647805873: Global MASTER-Net observations report
  59. Fermi trigger No 647624281: Global MASTER-Net observations report
  60. MAXI GRB210709.93: Global MASTER-Net observations report
  61. Fermi trigger No 647522278: Global MASTER-Net observations report
  62. GRB 210704B: AstroSat CZTI detection
  63. Fermi trigger No 647120009: Global MASTER-Net observations report
  64. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  65. Fermi GRB 210627B: Global MASTER-Net observations report
  66. Fermi GRB 210627A: Global MASTER-Net observations report
  67. Fermi GRB 210625A: Global MASTER-Net observations report
  68. Fermi trigger No 646189108: Global MASTER-Net observations report
  69. Fermi trigger No 646194855: Global MASTER-Net observations report
  70. Fermi GRB 210622B: Global MASTER-Net observations report
  71. Swift GRB210618.07: Global MASTER-Net observations report
  72. Fermi trigger No 645485036: Global MASTER-Net observations report
  73. Fermi GRB 210615A: Global MASTER-Net observations report
  74. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  75. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  76. GRB 210610B: Further SAO RAS optical observations
  77. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  78. GRB 210610B: iTelescope optical afterglow observations
  79. Fermi trigger No 645047470: Global MASTER-Net observations report
  80. GRB210610A: MeerLICHT multi-colour photometry
  81. GRB 210610A: MITSuME Akeno optical observation
  82. IPN triangulation of GRB 210605A (short)
  83. Fermi trigger No 644449593: Global MASTER-Net observations report
  84. Swift Detection of probable new Swift SGR J1555.2-5402
  85. Fermi trigger No 644359567: Global MASTER-Net observations report
  86. GRB 210602A: MAXI/GSC detection
  87. Fermi GRB 210601A: Global MASTER-Net observations report
  88. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  89. Fermi GRB 210529B: Global MASTER-Net observations report
  90. GRB 210524B: Fermi GBM Final Real-time Localization
  91. Fermi trigger No 643065622: Global MASTER-Net observations report
  92. Fermi trigger No 642991619: Global MASTER-Net observations report
  93. Fermi GRB 210516A: Global MASTER-Net observations report
  94. Fermi GRB 210515B: Global MASTER-Net observations report
  95. Fermi GRB 210515A: Global MASTER-Net observations report
  96. GRB 210514A: update on the BAT trigger time and burst duration
  97. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  98. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  99. Fermi GRB 210511A: Global MASTER-Net observations report
  100. Fermi GRB 210510A: Global MASTER-Net observations report

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