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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"

3119 results found.

  1. GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
  2. GRB 210919A: iTelescope T-11 upper limits
  3. IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
  4. IceCube Alert 210922.76: Global MASTER-Net observations report
  5. Swift GRB 210919A: Global MASTER-Net observations report
  6. GRB 210917A: Fermi GBM Final Real-time Localization
  7. AGILE observations of two bright bursts from SGR 1935+2154
  8. Fermi trigger No 653083551: Global MASTER-Net observations report
  9. Fermi trigger No 653066130: Global MASTER-Net observations report
  10. Fermi trigger No 653049776: Global MASTER-Net observations report
  11. Fermi trigger No 653010039: Global MASTER-Net observations report
  12. IPN triangulation of a bright burst from SGR 1935+2154
  13. Fermi trigger No 652927551: Global MASTER-Net observations report
  14. Fermi trigger No 652911693: Global MASTER-Net observations report
  15. Fermi trigger No 652906639: Global MASTER-Net observations report
  16. Fermi GRB 210909A: Global MASTER-Net observations report
  17. Fermi trigger No 652585475: Global MASTER-Net observations report
  18. GRB 210905A: Swift detection of a burst
  19. GRB 210904A: Fermi GBM Final Real-time Localization
  20. Fermi GRB 210903A: Global MASTER-Net observations report
  21. Fermi GRB 210827A: Global MASTER-Net observations report
  22. GRB 210827A: Swift/BAT-GUANO detection and arcminute localization
  23. GRB 210826A: Swift-XRT observations
  24. GRB 210822A: TSHAO continued optical observation
  25. GRB 210822A: TSHAO optical observation
  26. Swift GRB 210824A: Global MASTER-Net observations report
  27. Fermi trigger No 651306769: Global MASTER-Net observations report
  28. Fermi GRB 210822B: Global MASTER-Net observations report
  29. Konus-Wind detection of GRB 210818A
  30. GRB 210812A is consistent with being a lensed GRB
  31. IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
  32. Fermi GRB 210813A: Global MASTER-Net observations report
  33. GRB 210812A: BALROG localization (Fermi Trigger 650479626 / GRB 210812699)
  34. GRB 210812A: Fermi GBM Final Real-time Localization
  35. Fermi GRB 210807C: Global MASTER-Net observations report
  36. Fermi GRB 210807B: Global MASTER-Net observations report
  37. Swift GRB210731.62: Global MASTER-Net observations report
  38. GRB 210731A: MeerLICHT optical afterglow detection
  39. Trigger 1062273: Swift detection of 4U 1700-377
  40. IPN triangulation of GRB 210727A (short)
  41. Fermi trigger No 648959581: Global MASTER-Net observations report
  42. GRB 210725A: Fermi GBM detection
  43. GRB 210725A: CALET Gamma-Ray Burst Monitor detection
  44. Fermi trigger No 648868114: Global MASTER-Net observations report
  45. GRB 210725A: Swift detection of a burst
  46. GRB 210723A: Swift detection of a burst
  47. Fermi trigger No 648602917: Global MASTER-Net observations report
  48. Fermi trigger No 648278666: Global MASTER-Net observations report
  49. Fermi trigger No 647942198: Global MASTER-Net observations report
  50. Fermi trigger No 647805873: Global MASTER-Net observations report
  51. Fermi trigger No 647624281: Global MASTER-Net observations report
  52. MAXI GRB210709.93: Global MASTER-Net observations report
  53. Fermi trigger No 647522278: Global MASTER-Net observations report
  54. GRB 210704B: AstroSat CZTI detection
  55. Fermi trigger No 647120009: Global MASTER-Net observations report
  56. GRB 210702A: AGILE detection
  57. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  58. Fermi GRB 210627B: Global MASTER-Net observations report
  59. Fermi GRB 210627A: Global MASTER-Net observations report
  60. Fermi GRB 210625A: Global MASTER-Net observations report
  61. Fermi trigger No 646189108: Global MASTER-Net observations report
  62. Fermi trigger No 646194855: Global MASTER-Net observations report
  63. Fermi GRB 210622B: Global MASTER-Net observations report
  64. Swift GRB210618.07: Global MASTER-Net observations report
  65. Fermi trigger No 645485036: Global MASTER-Net observations report
  66. Fermi GRB 210615A: Global MASTER-Net observations report
  67. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  68. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  69. GRB 210610B: Further SAO RAS optical observations
  70. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  71. GRB 210610B: iTelescope optical afterglow observations
  72. Fermi trigger No 645047470: Global MASTER-Net observations report
  73. GRB210610A: MeerLICHT multi-colour photometry
  74. GRB 210610A: MITSuME Akeno optical observation
  75. IPN triangulation of GRB 210605A (short)
  76. Fermi trigger No 644449593: Global MASTER-Net observations report
  77. Swift Detection of probable new Swift SGR J1555.2-5402
  78. Fermi trigger No 644359567: Global MASTER-Net observations report
  79. GRB 210602A: MAXI/GSC detection
  80. Fermi GRB 210601A: Global MASTER-Net observations report
  81. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  82. Fermi GRB 210529B: Global MASTER-Net observations report
  83. GRB 210524B: Fermi GBM Final Real-time Localization
  84. Fermi trigger No 643065622: Global MASTER-Net observations report
  85. Fermi trigger No 642991619: Global MASTER-Net observations report
  86. Fermi GRB 210516A: Global MASTER-Net observations report
  87. Fermi GRB 210515B: Global MASTER-Net observations report
  88. Fermi GRB 210515A: Global MASTER-Net observations report
  89. GRB 210514A: update on the BAT trigger time and burst duration
  90. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  91. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  92. Fermi GRB 210511A: Global MASTER-Net observations report
  93. Fermi GRB 210510A: Global MASTER-Net observations report
  94. Swift trigger 1047857 is 4U 1700-377
  95. Fermi GRB 210507A: Global MASTER-Net observations report
  96. Fermi GRB 210501A: Global MASTER-Net observations report
  97. Fermi trigger No 641601187: Global MASTER-Net observations report
  98. Fermi GRB 210430B: Global MASTER-Net observations report
  99. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  100. GRB 210422A: Swift detection of a burst

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