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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"

3106 results found.

  1. Fermi trigger No 653066130: Global MASTER-Net observations report
  2. Fermi trigger No 653049776: Global MASTER-Net observations report
  3. Fermi trigger No 653010039: Global MASTER-Net observations report
  4. IPN triangulation of a bright burst from SGR 1935+2154
  5. Fermi trigger No 652927551: Global MASTER-Net observations report
  6. Fermi trigger No 652911693: Global MASTER-Net observations report
  7. Fermi trigger No 652906639: Global MASTER-Net observations report
  8. Fermi GRB 210909A: Global MASTER-Net observations report
  9. Fermi trigger No 652585475: Global MASTER-Net observations report
  10. GRB 210905A: Swift detection of a burst
  11. GRB 210904A: Fermi GBM Final Real-time Localization
  12. Fermi GRB 210903A: Global MASTER-Net observations report
  13. Fermi GRB 210827A: Global MASTER-Net observations report
  14. GRB 210827A: Swift/BAT-GUANO detection and arcminute localization
  15. GRB 210826A: Swift-XRT observations
  16. GRB 210822A: TSHAO continued optical observation
  17. GRB 210822A: TSHAO optical observation
  18. Swift GRB 210824A: Global MASTER-Net observations report
  19. Fermi trigger No 651306769: Global MASTER-Net observations report
  20. Fermi GRB 210822B: Global MASTER-Net observations report
  21. Konus-Wind detection of GRB 210818A
  22. GRB 210812A is consistent with being a lensed GRB
  23. IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
  24. Fermi GRB 210813A: Global MASTER-Net observations report
  25. GRB 210812A: BALROG localization (Fermi Trigger 650479626 / GRB 210812699)
  26. GRB 210812A: Fermi GBM Final Real-time Localization
  27. Fermi GRB 210807C: Global MASTER-Net observations report
  28. Fermi GRB 210807B: Global MASTER-Net observations report
  29. Swift GRB210731.62: Global MASTER-Net observations report
  30. GRB 210731A: MeerLICHT optical afterglow detection
  31. Trigger 1062273: Swift detection of 4U 1700-377
  32. IPN triangulation of GRB 210727A (short)
  33. Fermi trigger No 648959581: Global MASTER-Net observations report
  34. GRB 210725A: Fermi GBM detection
  35. GRB 210725A: CALET Gamma-Ray Burst Monitor detection
  36. Fermi trigger No 648868114: Global MASTER-Net observations report
  37. GRB 210725A: Swift detection of a burst
  38. GRB 210723A: Swift detection of a burst
  39. Fermi trigger No 648602917: Global MASTER-Net observations report
  40. Fermi trigger No 648278666: Global MASTER-Net observations report
  41. Fermi trigger No 647942198: Global MASTER-Net observations report
  42. Fermi trigger No 647805873: Global MASTER-Net observations report
  43. Fermi trigger No 647624281: Global MASTER-Net observations report
  44. MAXI GRB210709.93: Global MASTER-Net observations report
  45. Fermi trigger No 647522278: Global MASTER-Net observations report
  46. GRB 210704B: AstroSat CZTI detection
  47. Fermi trigger No 647120009: Global MASTER-Net observations report
  48. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  49. Fermi GRB 210627B: Global MASTER-Net observations report
  50. Fermi GRB 210627A: Global MASTER-Net observations report
  51. Fermi GRB 210625A: Global MASTER-Net observations report
  52. Fermi trigger No 646189108: Global MASTER-Net observations report
  53. Fermi trigger No 646194855: Global MASTER-Net observations report
  54. Fermi GRB 210622B: Global MASTER-Net observations report
  55. Swift GRB210618.07: Global MASTER-Net observations report
  56. Fermi trigger No 645485036: Global MASTER-Net observations report
  57. Fermi GRB 210615A: Global MASTER-Net observations report
  58. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  59. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  60. GRB 210610B: Further SAO RAS optical observations
  61. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  62. GRB 210610B: iTelescope optical afterglow observations
  63. Fermi trigger No 645047470: Global MASTER-Net observations report
  64. GRB210610A: MeerLICHT multi-colour photometry
  65. GRB 210610A: MITSuME Akeno optical observation
  66. IPN triangulation of GRB 210605A (short)
  67. Fermi trigger No 644449593: Global MASTER-Net observations report
  68. Swift Detection of probable new Swift SGR J1555.2-5402
  69. Fermi trigger No 644359567: Global MASTER-Net observations report
  70. GRB 210602A: MAXI/GSC detection
  71. Fermi GRB 210601A: Global MASTER-Net observations report
  72. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  73. Fermi GRB 210529B: Global MASTER-Net observations report
  74. GRB 210524B: Fermi GBM Final Real-time Localization
  75. Fermi trigger No 643065622: Global MASTER-Net observations report
  76. Fermi trigger No 642991619: Global MASTER-Net observations report
  77. Fermi GRB 210516A: Global MASTER-Net observations report
  78. Fermi GRB 210515B: Global MASTER-Net observations report
  79. Fermi GRB 210515A: Global MASTER-Net observations report
  80. GRB 210514A: update on the BAT trigger time and burst duration
  81. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  82. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  83. Fermi GRB 210511A: Global MASTER-Net observations report
  84. Fermi GRB 210510A: Global MASTER-Net observations report
  85. Swift trigger 1047857 is 4U 1700-377
  86. Fermi GRB 210507A: Global MASTER-Net observations report
  87. Fermi GRB 210501A: Global MASTER-Net observations report
  88. Fermi trigger No 641601187: Global MASTER-Net observations report
  89. Fermi GRB 210430B: Global MASTER-Net observations report
  90. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  91. GRB 210422A: Swift detection of a burst
  92. GRB 210420B: Tautenburg observations
  93. Fermi GRB 210420A: Global MASTER-Net observations report
  94. Swift GRB 210421A: Global MASTER-Net observations report
  95. GRB 210413B: LOAO optical upper limit
  96. GRB 210411B: AstroSat CZTI detection
  97. Fermi GRB 210411B: Global MASTER-Net observations report
  98. GRB 210406A: 10.4m GTC follow-up observation
  99. GRB 210411B: Fermi GBM Final Real-time Localization
  100. Fermi GRB 210411A: Global MASTER-Net observations report

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