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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 220411A: Fermi GBM Final Real-time Localization
  2. GRB 220408A: RATIR Optical and NIR Observations
  3. GRB 220403B: 1.3m DFOT Optical upper limit
  4. GRB 220408A: 1.3m DFOT Optical upper limit
  5. GRB 220408A: LOAO, DOAO, and, SAO optical upper limit
  6. GRB 220403C: Swift-XRT observations
  7. GRB 220408A: redshift lower limit estimating
  8. GRB 220408A: NOT optical observations and archival detection
  9. GRB 220408B: AstroSat CZTI detection
  10. GRB 220408A: LCO Optical Afterglow Detection
  11. GRB 220408A: Swift-XRT refined Analysis
  12. GRB 220403C: Swift ToO observations
  13. GRB 220408A: BOOTES-5/JGT optical afterglow detection
  14. Fermi GRB 220408B: Global MASTER-Net observations report
  15. GRB 220408A: GIT optical upper limit
  16. GRB 220408A: Fermi GBM observation
  17. GRB 220408A: Swift/UVOT Detection
  18. GRB 220408B: Fermi GBM Final Localization
  19. GRB 220408A: Xinglong-2.16m optical upper limit
  20. GRB 220408A: Enhanced Swift-XRT position
  21. Chandra upper limit at the location of GRB 220408A
  22. GRB 220408A: KAIT Optical Observations
  23. Fermi GRB 220408A: Global MASTER-Net observations report
  24. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  25. GRB 220408A: Fermi GBM Final Real-time Localization
  26. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, SAO RAS, CrAO)
  27. Fermi-LAT Gamma-ray Observations of IceCube-220405B
  28. GRB 220403B: Mondy optical upper limit
  29. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  30. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  31. GRB 220403B: 1.5m OSN optical observation
  32. IceCube Alert 220405.93: Global MASTER-Net observations report
  33. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 220404A: Swift-BAT refined analysis
  35. GRB 220403B: Kitab optical observations
  36. Fermi-LAT Gamma-ray Observations of IceCube-220405A
  37. GRB 220405A: Fermi GBM Final Localization
  38. GRB 220403B: Swift-BAT refined analysis
  39. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  40. IceCube Alert 220405.21: Global MASTER-Net observations report
  41. GRB 220404B: Fermi GBM Final Real-time Localization
  42. GRB 220403B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  43. GRB 220403B: Fermi GBM detection
  44. GRB 220404A: Swift detection of a burst
  45. GRB 220403B: Swift-XRT refined Analysis
  46. GRB 220403B: LBT observations
  47. Swift GRB 220403B: Global MASTER-Net observations report
  48. GRB 220403C (or A): Swift/BAT-GUANO detection outside the coded FOV
  49. GRB 220403B: Nanshan/NEXT optical afterglow power-law decay
  50. GRB 220403A: Tautenburg observations
  51. GRB 220403B: optical detection by D50
  52. GRB 220403B: Swift detection of a burst with an optical counterpart
  53. Fermi GRB 220403A: Global MASTER-Net observations report
  54. GRB 220403A: Fermi GBM Final Real-time Localization
  55. GRB 220401A: Swift/BAT-GUANO detection outside the coded FOV
  56. GRB 220401A: Fermi GBM observation
  57. Swift Trigger 1100848 is likely not a GRB
  58. Swift GRB220402.16: Global MASTER-Net observations report
  59. Fermi GRB 220401B: Global MASTER-Net observations report
  60. GRB 220401B: Fermi GBM Final Real-time Localization
  61. GRB 220401A: Fermi GBM Final Localization
  62. Fermi trigger No 670501065: Global MASTER-Net observations report
  63. Fermi Gamma-ray Burst Monitor trigger 220331776/670444627 is not a GRB
  64. GRB 220331A: Fermi GBM Final Real-time Localization
  65. Fermi GRB 220330A: Global MASTER-Net observations report
  66. GRB 220330A: Fermi GBM Final Real-time Localization
  67. ZTF22aaajecp/AT2022cmc: 1.3m DFOT Optical observations
  68. GRB 220325A: GRANDMA observations
  69. GRB 220320A: Detection by VZLUSAT-2
  70. Konus-Wind observation of GRB 220320A
  71. GRB 220325A: Swift/UVOT Upper Limits
  72. GRB 211024B: Host galaxy redshift from X-shooter/VLT
  73. GRB 220325A: Swift-BAT refined analysis
  74. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, TSHAO, AbAO)
  75. GRB 220325A: Tautenburg observations
  76. GRB 220326A: Fermi GBM Final Localization
  77. GRB 220325A: LCO Optical Upper Limits
  78. GRB 220325A: Swift-XRT refined Analysis
  79. GRB 220325A: 1.3m DFOT Optical upper limit
  80. GRB 220325B: Fermi GBM Final Localization
  81. Fermi GBM Sub-Threshold Detection of GRB 220325A
  82. GRB 220325A: Enhanced Swift-XRT position
  83. GRB 220325A: MASTER Global Robotic Net optical observations
  84. GRB 220324A: AstroSat CZTI detection
  85. GRB 220325A: Swift detection of a burst
  86. GRB 220323A: AstroSat CZTI detection
  87. GRB 220319A: GRANDMA observations
  88. GRB 220323A: AGILE/MCAL detection
  89. IPN triangulation of GRB 220320A
  90. GRB 220323A: Fermi GBM Final Real-time Localization
  91. GRB 220319A: Swift-BAT refined analysis
  92. GRB 220316A: AstroSat CZTI detection
  93. GRB 220320A: AstroSat CZTI detection
  94. GRB 220317A: Fermi GBM detection
  95. GRB 220321A: Fermi GBM Final Localization
  96. GRB 220319A: MITSuME Akeno optical upper limits
  97. GRB220319A: Optical observations from NOT
  98. GRB 220319A: LCO Optical Upper Limit
  99. GRB 220319A: Mondy optical uper limit
  100. GRB 220319A: Swift-XRT refined Analysis

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