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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. Fermi trigger No 643548039: Global MASTER-Net observations report
  2. GRB 210524B: Fermi GBM Final Real-time Localization
  3. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  4. Fermi GRB 210524A: Global MASTER-Net observations report
  5. GRB 210524A: Fermi GBM Final Real-time Localization
  6. GRB 210522A: GECAM detection
  7. GRB 210520A: Swift-XRT observations
  8. MAXI GRB210521.54: Global MASTER-Net observations report
  9. GRB 210521A: MAXI/GSC detection
  10. GRB210413B: further Swift-XRT observations
  11. GRB 210520A: Fermi GBM detection
  12. ZTF21aayokph (AT2021lfa): continued Assy optical observations
  13. GRB 210520A: Tiled Swift observations
  14. GRB 210520A: Fermi-LAT detection
  15. GRB 210520A: GECAM detection
  16. Fermi GRB 210520A: Global MASTER-Net observations report
  17. GRB 210520A: Fermi GBM Final Real-time Localization
  18. Fermi GBM observation of a bright burst from magneta
  19. GRB 210517A: KCT optical upper limit
  20. IceCube GCN alert 135302_36915486.amon retraction
  21. Fermi GRB 210519A: Global MASTER-Net observations report
  22. IceCube Alert 210519.86: Global MASTER-Net observations report
  23. IPN triangulation of GRB 210518A
  24. Fermi trigger No 643065622: Global MASTER-Net observations report
  25. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  26. GRB 210519A: Fermi GBM Final Localization
  27. Fermi GRB 210518A: Global MASTER-Net observations report
  28. Konus-Wind detection of GRB 210514A
  29. Fermi trigger No 642991619: Global MASTER-Net observations report
  30. Fermi-LAT Gamma-ray Observations of IceCube-210516A
  31. GRB 210518A: Fermi GBM Final Real-time Localization
  32. IceCube Alert 210515.01: Global MASTER-Net observations report
  33. GRB 210517A: Swift-BAT refined analysis
  34. GRB 210517A: Swift-XRT refined Analysis
  35. IceCube-210516A: No significant detection in HAWC
  36. GRB 210517A: Swift/UVOT Upper Limits
  37. GRB 210515C: Swift/UVOT Upper Limits
  38. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 210517A: VLT/X-shooter optical afterglow and redshift
  40. GRB 210517A: AGILE detection
  41. GRB 210514A: CALET Gamma-Ray Burst Monitor detection
  42. GRB 210517A: Enhanced Swift-XRT position
  43. Swift GRB 210517A: Global MASTER-Net observations report
  44. GRB 210517A: Swift detection of a burst
  45. Fermi GRB 210516A: Global MASTER-Net observations report
  46. GRB 210516A: Fermi GBM Final Real-time Localization
  47. IceCube Alert 210516.61: Global MASTER-Net observations report
  48. GRB 210515C: LCO Optical Upper Limit
  49. GRB 210504A: LCO Optical Afterglow Detection
  50. IceCube-210516A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 210514A: Swift/UVOT Upper Limits
  52. AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
  53. GRB 210515C: Swift-XRT refined Analysis
  54. Swift GRB210515.83: Global MASTER-Net observations report
  55. GRB 210515C: Swift-BAT refined analysis
  56. GRB 210515C: Swift detection of a burst
  57. Fermi GRB 210515B: Global MASTER-Net observations report
  58. GRB 210514A: Swift-BAT refined analysis
  59. Fermi GRB 210515A: Global MASTER-Net observations report
  60. GRB 210515B: Fermi GBM Final Real-time Localization
  61. GRB 210515A: Fermi GBM Final Real-time Localization
  62. Swift GRB210514.71: Global MASTER-Net observations report
  63. GRB 210514A: Swift XRT light curve is fading
  64. GRB 210514A: Swift-XRT refined Analysis
  65. GRB 210514A: Enhanced Swift-XRT position
  66. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEM-210515A and 210515B
  67. GRB 210514A: update on the BAT trigger time and burst duration
  68. GRB 210514A: Swift detection of a burst
  69. Konus-Wind detection of GRB 210511B
  70. GRB 210512.786: DDOTI Upper Limits on the Afterglow
  71. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  72. Fermi trigger No 642538568: Global MASTER-Net observations report
  73. IceCube-210510A: Upper limits from a search for additional neutrino events in IceCube
  74. IPN triangulation of GRB 210511B
  75. IceCube-210510A: not observable by Fermi-GBM
  76. Short GRB 210323A: likely host galaxy detection
  77. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  78. GRB 210511B: DDOTI Upper Limits on the Afterglow
  79. IPN triangulation of GRB 210427A
  80. GRB 210511B: Fermi GBM observation
  81. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  82. Fermi GRB 210511A: Global MASTER-Net observations report
  83. Fermi GRB 210510A: DDOTI Upper Limits on the Afterglow
  84. Fermi GRB 210511B: Global MASTER-Net observations report
  85. GRB 210511B: AGILE detection
  86. GRB 210511B: GECAM detection
  87. GRB 210511B: BALROG localization (Fermi Trigger 642425204 / GRB 210511477)
  88. GRB 210511B: Fermi GBM Final Real-time Localization
  89. GRB 210511A: Fermi GBM Final Real-time Localization
  90. Fermi GRB 210510A: Global MASTER-Net observations report
  91. GRB 201228B: Swift/BAT-GUANO archival detection and arcminute localization
  92. GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization
  93. Swift trigger 1047857 is 4U 1700-377
  94. IceCube Alert 210510.20: Global MASTER-Net observations report
  95. GRB 210510A: Fermi GBM Final Real-time Localization
  96. IceCube-210510A: DDOTI Upper Limits
  97. GRB 210509A: RATIR Optical and NIR Upper Limits
  98. GRB 210509A: Swift/UVOT Upper Limits
  99. GRB 210509A: Swift-XRT refined Analysis
  100. IceCube-210510A - IceCube observation of a high-energy neutrino candidate track-like event

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