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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. Swift GRB 220412B: Global MASTER-Net observations report
  2. GRB 220408A: HCT optical upper limit
  3. GRB 220412B: GIT optical upper limit
  4. GRB 220412A: MITSuME Akeno optical upper limits
  5. Correction to GCN 31888: GRB 220412A: Swift-XRT refined Analysis
  6. GRB 220412B: MITSuME Akeno optical upper limits
  7. GRB 220412A: Swift-XRT refined Analysis
  8. GRB 220412A: Enhanced Swift-XRT position
  9. GRB 220412B: Swift detection of a short burst
  10. GRB 220412A: Swift/UVOT Upper Limits
  11. GRB 220408A: GRANDMA observations
  12. GRB 220403B: GRANDMA observations
  13. GRB 220412A: RATIR Afterglow Candidate
  14. GRB 220412A: Swift detection of a burst
  15. Swift GRB220412.28: Global MASTER-Net observations report
  16. GRB 220411A: AstroSat CZTI detection
  17. IPN triangulation of GRB 220408B
  18. IPN triangulation of GRB 220403C
  19. GRB 220403B: Swift/UVOT Detection
  20. GRB 220408A: Lowell Discovery Telescope Optical Observations
  21. GRB 220408A: Swift-BAT refined analysis
  22. Fermi GRB 220411A: Global MASTER-Net observations report
  23. GRB 220411A: BALROG localization (Fermi Trigger 671354405/ GRB 220411306)
  24. GRB 220411A: Fermi GBM Final Real-time Localization
  25. GRB 220408A: RATIR Optical and NIR Observations
  26. GRB 220403B: 1.3m DFOT Optical upper limit
  27. GRB 220408A: 1.3m DFOT Optical upper limit
  28. GRB 220408A: LOAO, DOAO, and, SAO optical upper limit
  29. GRB 220403C: Swift-XRT observations
  30. GRB 220408A: redshift lower limit estimating
  31. GRB 220408A: NOT optical observations and archival detection
  32. GRB 220408B: AstroSat CZTI detection
  33. GRB 220408A: LCO Optical Afterglow Detection
  34. GRB 220408A: Swift-XRT refined Analysis
  35. GRB 220403C: Swift ToO observations
  36. GRB 220408A: BOOTES-5/JGT optical afterglow detection
  37. Fermi GRB 220408B: Global MASTER-Net observations report
  38. GRB 220408A: GIT optical upper limit
  39. GRB 220408A: Fermi GBM observation
  40. GRB 220408A: Swift/UVOT Detection
  41. GRB 220408B: Fermi GBM Final Localization
  42. GRB 220408A: Xinglong-2.16m optical upper limit
  43. GRB 220408A: Enhanced Swift-XRT position
  44. Chandra upper limit at the location of GRB 220408A
  45. GRB 220408A: KAIT Optical Observations
  46. Fermi GRB 220408A: Global MASTER-Net observations report
  47. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  48. GRB 220408A: Fermi GBM Final Real-time Localization
  49. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, SAO RAS, CrAO)
  50. Fermi-LAT Gamma-ray Observations of IceCube-220405B
  51. GRB 220403B: Mondy optical upper limit
  52. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  53. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  54. GRB 220403B: 1.5m OSN optical observation
  55. IceCube Alert 220405.93: Global MASTER-Net observations report
  56. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 220404A: Swift-BAT refined analysis
  58. GRB 220403B: Kitab optical observations
  59. Fermi-LAT Gamma-ray Observations of IceCube-220405A
  60. GRB 220405A: Fermi GBM Final Localization
  61. GRB 220403B: Swift-BAT refined analysis
  62. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  63. IceCube Alert 220405.21: Global MASTER-Net observations report
  64. GRB 220404B: Fermi GBM Final Real-time Localization
  65. GRB 220403B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  66. GRB 220403B: Fermi GBM detection
  67. GRB 220404A: Swift detection of a burst
  68. GRB 220403B: Swift-XRT refined Analysis
  69. GRB 220403B: LBT observations
  70. Swift GRB 220403B: Global MASTER-Net observations report
  71. GRB 220403C (or A): Swift/BAT-GUANO detection outside the coded FOV
  72. GRB 220403B: Nanshan/NEXT optical afterglow power-law decay
  73. GRB 220403A: Tautenburg observations
  74. GRB 220403B: optical detection by D50
  75. GRB 220403B: Swift detection of a burst with an optical counterpart
  76. Fermi GRB 220403A: Global MASTER-Net observations report
  77. GRB 220403A: Fermi GBM Final Real-time Localization
  78. GRB 220401A: Swift/BAT-GUANO detection outside the coded FOV
  79. GRB 220401A: Fermi GBM observation
  80. Swift Trigger 1100848 is likely not a GRB
  81. Swift GRB220402.16: Global MASTER-Net observations report
  82. Fermi GRB 220401B: Global MASTER-Net observations report
  83. GRB 220401B: Fermi GBM Final Real-time Localization
  84. GRB 220401A: Fermi GBM Final Localization
  85. Fermi trigger No 670501065: Global MASTER-Net observations report
  86. Fermi Gamma-ray Burst Monitor trigger 220331776/670444627 is not a GRB
  87. GRB 220331A: Fermi GBM Final Real-time Localization
  88. Fermi GRB 220330A: Global MASTER-Net observations report
  89. GRB 220330A: Fermi GBM Final Real-time Localization
  90. ZTF22aaajecp/AT2022cmc: 1.3m DFOT Optical observations
  91. GRB 220325A: GRANDMA observations
  92. GRB 220320A: Detection by VZLUSAT-2
  93. Konus-Wind observation of GRB 220320A
  94. GRB 220325A: Swift/UVOT Upper Limits
  95. GRB 211024B: Host galaxy redshift from X-shooter/VLT
  96. GRB 220325A: Swift-BAT refined analysis
  97. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, TSHAO, AbAO)
  98. GRB 220325A: Tautenburg observations
  99. GRB 220326A: Fermi GBM Final Localization
  100. GRB 220325A: LCO Optical Upper Limits

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