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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 220408A: NOT optical observations and archival detection
  2. GRB 220408B: AstroSat CZTI detection
  3. GRB 220408A: LCO Optical Afterglow Detection
  4. GRB 220408A: Swift-XRT refined Analysis
  5. GRB 220403C: Swift ToO observations
  6. GRB 220408A: BOOTES-5/JGT optical afterglow detection
  7. Fermi GRB 220408B: Global MASTER-Net observations report
  8. GRB 220408A: GIT optical upper limit
  9. GRB 220408A: Fermi GBM observation
  10. GRB 220408A: Swift/UVOT Detection
  11. GRB 220408B: Fermi GBM Final Localization
  12. GRB 220408A: Xinglong-2.16m optical upper limit
  13. GRB 220408A: Enhanced Swift-XRT position
  14. Chandra upper limit at the location of GRB 220408A
  15. GRB 220408A: KAIT Optical Observations
  16. Fermi GRB 220408A: Global MASTER-Net observations report
  17. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  18. GRB 220408A: Fermi GBM Final Real-time Localization
  19. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, SAO RAS, CrAO)
  20. Fermi-LAT Gamma-ray Observations of IceCube-220405B
  21. GRB 220403B: Mondy optical upper limit
  22. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  23. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  24. GRB 220403B: 1.5m OSN optical observation
  25. IceCube Alert 220405.93: Global MASTER-Net observations report
  26. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 220404A: Swift-BAT refined analysis
  28. GRB 220403B: Kitab optical observations
  29. Fermi-LAT Gamma-ray Observations of IceCube-220405A
  30. GRB 220405A: Fermi GBM Final Localization
  31. GRB 220403B: Swift-BAT refined analysis
  32. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  33. IceCube Alert 220405.21: Global MASTER-Net observations report
  34. GRB 220404B: Fermi GBM Final Real-time Localization
  35. GRB 220403B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  36. GRB 220403B: Fermi GBM detection
  37. GRB 220404A: Swift detection of a burst
  38. GRB 220403B: Swift-XRT refined Analysis
  39. GRB 220403B: LBT observations
  40. Swift GRB 220403B: Global MASTER-Net observations report
  41. GRB 220403C (or A): Swift/BAT-GUANO detection outside the coded FOV
  42. GRB 220403B: Nanshan/NEXT optical afterglow power-law decay
  43. GRB 220403A: Tautenburg observations
  44. GRB 220403B: optical detection by D50
  45. GRB 220403B: Swift detection of a burst with an optical counterpart
  46. Fermi GRB 220403A: Global MASTER-Net observations report
  47. GRB 220403A: Fermi GBM Final Real-time Localization
  48. GRB 220401A: Swift/BAT-GUANO detection outside the coded FOV
  49. GRB 220401A: Fermi GBM observation
  50. Swift Trigger 1100848 is likely not a GRB
  51. Swift GRB220402.16: Global MASTER-Net observations report
  52. Fermi GRB 220401B: Global MASTER-Net observations report
  53. GRB 220401B: Fermi GBM Final Real-time Localization
  54. GRB 220401A: Fermi GBM Final Localization
  55. Fermi trigger No 670501065: Global MASTER-Net observations report
  56. Fermi Gamma-ray Burst Monitor trigger 220331776/670444627 is not a GRB
  57. GRB 220331A: Fermi GBM Final Real-time Localization
  58. Fermi GRB 220330A: Global MASTER-Net observations report
  59. GRB 220330A: Fermi GBM Final Real-time Localization
  60. ZTF22aaajecp/AT2022cmc: 1.3m DFOT Optical observations
  61. GRB 220325A: GRANDMA observations
  62. GRB 220320A: Detection by VZLUSAT-2
  63. Konus-Wind observation of GRB 220320A
  64. GRB 220325A: Swift/UVOT Upper Limits
  65. GRB 211024B: Host galaxy redshift from X-shooter/VLT
  66. GRB 220325A: Swift-BAT refined analysis
  67. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, TSHAO, AbAO)
  68. GRB 220325A: Tautenburg observations
  69. GRB 220326A: Fermi GBM Final Localization
  70. GRB 220325A: LCO Optical Upper Limits
  71. GRB 220325A: Swift-XRT refined Analysis
  72. GRB 220325A: 1.3m DFOT Optical upper limit
  73. GRB 220325B: Fermi GBM Final Localization
  74. Fermi GBM Sub-Threshold Detection of GRB 220325A
  75. GRB 220325A: Enhanced Swift-XRT position
  76. GRB 220325A: MASTER Global Robotic Net optical observations
  77. GRB 220324A: AstroSat CZTI detection
  78. GRB 220325A: Swift detection of a burst
  79. GRB 220323A: AstroSat CZTI detection
  80. GRB 220319A: GRANDMA observations
  81. GRB 220323A: AGILE/MCAL detection
  82. IPN triangulation of GRB 220320A
  83. GRB 220323A: Fermi GBM Final Real-time Localization
  84. GRB 220319A: Swift-BAT refined analysis
  85. GRB 220316A: AstroSat CZTI detection
  86. GRB 220320A: AstroSat CZTI detection
  87. GRB 220317A: Fermi GBM detection
  88. GRB 220321A: Fermi GBM Final Localization
  89. GRB 220319A: MITSuME Akeno optical upper limits
  90. GRB220319A: Optical observations from NOT
  91. GRB 220319A: LCO Optical Upper Limit
  92. GRB 220319A: Mondy optical uper limit
  93. GRB 220319A: Swift-XRT refined Analysis
  94. GRB 220319A: Enhanced Swift-XRT position
  95. GRB 220319A: MASTER Global Robotic Net optical observations
  96. GRB 220319A: Swift detection of a burst
  97. Fermi-LAT Gamma-ray Observations of IceCube-220317A
  98. IceCube-220317A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 220317A: Swift/BAT-GUANO detection outside the coded FOV
  100. GRB 220310A: MITSuME Akeno optical observation

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