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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. GRB 210528A: Fermi GBM Final Real-time Localization
  2. GRB 210527A: Swift/UVOT Observations
  3. GRB 210527A: GIT optical upper limit
  4. GRB 210527A: MITSuME Akeno optical upper limits
  5. Swift GRB 210527A: Global MASTER-Net observations report
  6. GRB 210527A: Swift-XRT refined Analysis
  7. GRB 210527A: RATIR Optical and NIR Observations
  8. GRB 210527A: Enhanced Swift-XRT position
  9. GRB 210527A: Swift-XRT observations
  10. GRB 210527A: Swift detection of a burst
  11. GRB 210306A: LBT observations of the likely host galaxy
  12. ZTF21aayokph (AT2021lfa): LBT optical observations
  13. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  14. Konus-Wind detection of GRB 210524A
  15. IPN triangulation of GRB 210524A
  16. Fermi trigger No 643548039: Global MASTER-Net observations report
  17. GRB 210524B: Fermi GBM Final Real-time Localization
  18. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  19. Fermi GRB 210524A: Global MASTER-Net observations report
  20. GRB 210524A: Fermi GBM Final Real-time Localization
  21. GRB 210522A: GECAM detection
  22. GRB 210520A: Swift-XRT observations
  23. MAXI GRB210521.54: Global MASTER-Net observations report
  24. GRB 210521A: MAXI/GSC detection
  25. GRB210413B: further Swift-XRT observations
  26. GRB 210520A: Fermi GBM detection
  27. ZTF21aayokph (AT2021lfa): continued Assy optical observations
  28. GRB 210520A: Tiled Swift observations
  29. GRB 210520A: Fermi-LAT detection
  30. GRB 210520A: GECAM detection
  31. Fermi GRB 210520A: Global MASTER-Net observations report
  32. GRB 210520A: Fermi GBM Final Real-time Localization
  33. Fermi GBM observation of a bright burst from magneta
  34. GRB 210517A: KCT optical upper limit
  35. IceCube GCN alert 135302_36915486.amon retraction
  36. Fermi GRB 210519A: Global MASTER-Net observations report
  37. IceCube Alert 210519.86: Global MASTER-Net observations report
  38. IPN triangulation of GRB 210518A
  39. Fermi trigger No 643065622: Global MASTER-Net observations report
  40. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  41. GRB 210519A: Fermi GBM Final Localization
  42. Fermi GRB 210518A: Global MASTER-Net observations report
  43. Konus-Wind detection of GRB 210514A
  44. Fermi trigger No 642991619: Global MASTER-Net observations report
  45. Fermi-LAT Gamma-ray Observations of IceCube-210516A
  46. GRB 210518A: Fermi GBM Final Real-time Localization
  47. IceCube Alert 210515.01: Global MASTER-Net observations report
  48. GRB 210517A: Swift-BAT refined analysis
  49. GRB 210517A: Swift-XRT refined Analysis
  50. IceCube-210516A: No significant detection in HAWC
  51. GRB 210517A: Swift/UVOT Upper Limits
  52. GRB 210515C: Swift/UVOT Upper Limits
  53. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 210517A: VLT/X-shooter optical afterglow and redshift
  55. GRB 210517A: AGILE detection
  56. GRB 210514A: CALET Gamma-Ray Burst Monitor detection
  57. GRB 210517A: Enhanced Swift-XRT position
  58. Swift GRB 210517A: Global MASTER-Net observations report
  59. GRB 210517A: Swift detection of a burst
  60. Fermi GRB 210516A: Global MASTER-Net observations report
  61. GRB 210516A: Fermi GBM Final Real-time Localization
  62. IceCube Alert 210516.61: Global MASTER-Net observations report
  63. GRB 210515C: LCO Optical Upper Limit
  64. GRB 210504A: LCO Optical Afterglow Detection
  65. IceCube-210516A - IceCube observation of a high-energy neutrino candidate track-like event
  66. GRB 210514A: Swift/UVOT Upper Limits
  67. AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
  68. GRB 210515C: Swift-XRT refined Analysis
  69. Swift GRB210515.83: Global MASTER-Net observations report
  70. GRB 210515C: Swift-BAT refined analysis
  71. GRB 210515C: Swift detection of a burst
  72. Fermi GRB 210515B: Global MASTER-Net observations report
  73. GRB 210514A: Swift-BAT refined analysis
  74. Fermi GRB 210515A: Global MASTER-Net observations report
  75. GRB 210515B: Fermi GBM Final Real-time Localization
  76. GRB 210515A: Fermi GBM Final Real-time Localization
  77. Swift GRB210514.71: Global MASTER-Net observations report
  78. GRB 210514A: Swift XRT light curve is fading
  79. GRB 210514A: Swift-XRT refined Analysis
  80. GRB 210514A: Enhanced Swift-XRT position
  81. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEM-210515A and 210515B
  82. GRB 210514A: update on the BAT trigger time and burst duration
  83. GRB 210514A: Swift detection of a burst
  84. Konus-Wind detection of GRB 210511B
  85. GRB 210512.786: DDOTI Upper Limits on the Afterglow
  86. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  87. Fermi trigger No 642538568: Global MASTER-Net observations report
  88. IceCube-210510A: Upper limits from a search for additional neutrino events in IceCube
  89. IPN triangulation of GRB 210511B
  90. IceCube-210510A: not observable by Fermi-GBM
  91. Short GRB 210323A: likely host galaxy detection
  92. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  93. GRB 210511B: DDOTI Upper Limits on the Afterglow
  94. IPN triangulation of GRB 210427A
  95. GRB 210511B: Fermi GBM observation
  96. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  97. Fermi GRB 210511A: Global MASTER-Net observations report
  98. Fermi GRB 210510A: DDOTI Upper Limits on the Afterglow
  99. Fermi GRB 210511B: Global MASTER-Net observations report
  100. GRB 210511B: AGILE detection

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