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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 220412A: Swift-XRT refined Analysis
  2. GRB 220412A: Enhanced Swift-XRT position
  3. GRB 220412B: Swift detection of a short burst
  4. GRB 220412A: Swift/UVOT Upper Limits
  5. GRB 220408A: GRANDMA observations
  6. GRB 220403B: GRANDMA observations
  7. GRB 220412A: RATIR Afterglow Candidate
  8. GRB 220412A: Swift detection of a burst
  9. Swift GRB220412.28: Global MASTER-Net observations report
  10. GRB 220411A: AstroSat CZTI detection
  11. IPN triangulation of GRB 220408B
  12. IPN triangulation of GRB 220403C
  13. GRB 220403B: Swift/UVOT Detection
  14. GRB 220408A: Lowell Discovery Telescope Optical Observations
  15. GRB 220408A: Swift-BAT refined analysis
  16. Fermi GRB 220411A: Global MASTER-Net observations report
  17. GRB 220411A: BALROG localization (Fermi Trigger 671354405/ GRB 220411306)
  18. GRB 220411A: Fermi GBM Final Real-time Localization
  19. GRB 220408A: RATIR Optical and NIR Observations
  20. GRB 220403B: 1.3m DFOT Optical upper limit
  21. GRB 220408A: 1.3m DFOT Optical upper limit
  22. GRB 220408A: LOAO, DOAO, and, SAO optical upper limit
  23. GRB 220403C: Swift-XRT observations
  24. GRB 220408A: redshift lower limit estimating
  25. GRB 220408A: NOT optical observations and archival detection
  26. GRB 220408B: AstroSat CZTI detection
  27. GRB 220408A: LCO Optical Afterglow Detection
  28. GRB 220408A: Swift-XRT refined Analysis
  29. GRB 220403C: Swift ToO observations
  30. GRB 220408A: BOOTES-5/JGT optical afterglow detection
  31. Fermi GRB 220408B: Global MASTER-Net observations report
  32. GRB 220408A: GIT optical upper limit
  33. GRB 220408A: Fermi GBM observation
  34. GRB 220408A: Swift/UVOT Detection
  35. GRB 220408B: Fermi GBM Final Localization
  36. GRB 220408A: Xinglong-2.16m optical upper limit
  37. GRB 220408A: Enhanced Swift-XRT position
  38. Chandra upper limit at the location of GRB 220408A
  39. GRB 220408A: KAIT Optical Observations
  40. Fermi GRB 220408A: Global MASTER-Net observations report
  41. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  42. GRB 220408A: Fermi GBM Final Real-time Localization
  43. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, SAO RAS, CrAO)
  44. Fermi-LAT Gamma-ray Observations of IceCube-220405B
  45. GRB 220403B: Mondy optical upper limit
  46. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  47. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  48. GRB 220403B: 1.5m OSN optical observation
  49. IceCube Alert 220405.93: Global MASTER-Net observations report
  50. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 220404A: Swift-BAT refined analysis
  52. GRB 220403B: Kitab optical observations
  53. Fermi-LAT Gamma-ray Observations of IceCube-220405A
  54. GRB 220405A: Fermi GBM Final Localization
  55. GRB 220403B: Swift-BAT refined analysis
  56. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  57. IceCube Alert 220405.21: Global MASTER-Net observations report
  58. GRB 220404B: Fermi GBM Final Real-time Localization
  59. GRB 220403B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  60. GRB 220403B: Fermi GBM detection
  61. GRB 220404A: Swift detection of a burst
  62. GRB 220403B: Swift-XRT refined Analysis
  63. GRB 220403B: LBT observations
  64. Swift GRB 220403B: Global MASTER-Net observations report
  65. GRB 220403C (or A): Swift/BAT-GUANO detection outside the coded FOV
  66. GRB 220403B: Nanshan/NEXT optical afterglow power-law decay
  67. GRB 220403A: Tautenburg observations
  68. GRB 220403B: optical detection by D50
  69. GRB 220403B: Swift detection of a burst with an optical counterpart
  70. Fermi GRB 220403A: Global MASTER-Net observations report
  71. GRB 220403A: Fermi GBM Final Real-time Localization
  72. GRB 220401A: Swift/BAT-GUANO detection outside the coded FOV
  73. GRB 220401A: Fermi GBM observation
  74. Swift Trigger 1100848 is likely not a GRB
  75. Swift GRB220402.16: Global MASTER-Net observations report
  76. Fermi GRB 220401B: Global MASTER-Net observations report
  77. GRB 220401B: Fermi GBM Final Real-time Localization
  78. GRB 220401A: Fermi GBM Final Localization
  79. Fermi trigger No 670501065: Global MASTER-Net observations report
  80. Fermi Gamma-ray Burst Monitor trigger 220331776/670444627 is not a GRB
  81. GRB 220331A: Fermi GBM Final Real-time Localization
  82. Fermi GRB 220330A: Global MASTER-Net observations report
  83. GRB 220330A: Fermi GBM Final Real-time Localization
  84. ZTF22aaajecp/AT2022cmc: 1.3m DFOT Optical observations
  85. GRB 220325A: GRANDMA observations
  86. GRB 220320A: Detection by VZLUSAT-2
  87. Konus-Wind observation of GRB 220320A
  88. GRB 220325A: Swift/UVOT Upper Limits
  89. GRB 211024B: Host galaxy redshift from X-shooter/VLT
  90. GRB 220325A: Swift-BAT refined analysis
  91. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, TSHAO, AbAO)
  92. GRB 220325A: Tautenburg observations
  93. GRB 220326A: Fermi GBM Final Localization
  94. GRB 220325A: LCO Optical Upper Limits
  95. GRB 220325A: Swift-XRT refined Analysis
  96. GRB 220325A: 1.3m DFOT Optical upper limit
  97. GRB 220325B: Fermi GBM Final Localization
  98. Fermi GBM Sub-Threshold Detection of GRB 220325A
  99. GRB 220325A: Enhanced Swift-XRT position
  100. GRB 220325A: MASTER Global Robotic Net optical observations

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