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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 220930A: LCOGT Optical Upper Limits
  2. GRB 220930A: Swift/UVOT Upper Limits
  3. GRB 220930A: Enhanced Swift-XRT position
  4. Swift GRB 220930A: Global MASTER-Net observations report
  5. GRB 220930A: BOOTES-5/JGT early optical upper limit
  6. GRB 220930A: Prompt enhanced Swift-XRT position
  7. GRB 220930A: COATLI Upper Limits
  8. GRB 220930A: Swift detection of a burst
  9. Fermi-LAT gamma-ray observations of IceCube-220928A
  10. IceCube-220928A: Upper limits from a search for additional neutrino events in IceCube
  11. Konus-Wind detection of GRB 220927A
  12. IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event
  13. Fermi GRB 220927A: Global MASTER-Net observations report
  14. IPN triangulation of GRB 220927A (long)
  15. GRB 220921A: LCOGT Optical Observations
  16. GRB 220611A: Host galaxy redshift from VLT/X-shooter
  17. GRB 220927A: Fermi GBM Final Localization
  18. GRB 220924A: Fermi GBM detection
  19. Integral GRB220926.44: Global MASTER-Net observations report
  20. Ultra-long GRB 220525B: Konus-Wind and Fermi-GBM detection
  21. Swift Trigger 1125354 (GRB 220926A) is not a GRB
  22. Swift GRB220926.34: Global MASTER-Net observations report
  23. Swift GRB 220926A: Global MASTER-Net observations report
  24. Analysis of long GRB 220926B detected by INTEGRAL
  25. GRB 220926B
  26. GRB 220926A: Swift detection of a burst
  27. Fermi GRB 220925A: Global MASTER-Net observations report
  28. GRB 220924A: Swift/BAT-GUANO detection outside the coded FOV
  29. GRB 220921A: further MeerLICHT observations
  30. GRB 220925A: Fermi GBM Final Real-time Localization
  31. Fermi trigger No 685748699: Global MASTER-Net observations report
  32. GRB 220924A: Fermi GBM Final Real-time Localization
  33. Swift GRB220923.47: Global MASTER-Net observations report
  34. GRB 220921A: ALMA detection
  35. GRB 220921A: DDOTI Detection of the Afterglow
  36. Konus-Wind detection of GRB 220921A
  37. GRB 220921A: Fermi GBM detection
  38. IceCube-220907A: Classification of AT2022oyn as a Type Ia supernova
  39. GRB 220921A: MeerLICHT afterglow observations
  40. GRB 220921A: Swift-XRT Observations
  41. GRB 220921A: MASTER OT inside Fermi-LAT error-box
  42. LAT GRB220921.46: Global MASTER-Net observations report
  43. GRB 220921A: Fermi-LAT detection
  44. GRB 220921A: Tiled Swift observations
  45. Fermi trigger No 685452089: Global MASTER-Net observations report
  46. Fermi-LAT gamma-ray observations of IceCube-220918A and detection of a new gamma-ray source, Fermi J0502.5+0037
  47. IceCube-220918A: Upper limits from a search for additional neutrino events in IceCube
  48. IceCube Alert 220918.53: Global MASTER-Net observations report
  49. IceCube-220918A - IceCube observation of a high-energy neutrino candidate track-like event
  50. Fermi trigger No 684894705: Global MASTER-Net observations report
  51. IceCube-220907A: No significant detection in HAWC
  52. Improved IPN error box for GRB 220910A
  53. Fermi trigger No 684927323: Global MASTER-Net observations report
  54. Fermi trigger No 684911625: Global MASTER-Net observations report
  55. GRB 220909A: Fermi GBM observation
  56. Konus-Wind detection of GRB 220910A
  57. GRB 220910B: Fermi GBM Final Localization
  58. Fermi trigger No 684716840: Global MASTER-Net observations report
  59. Fermi GRB 220912A: Global MASTER-Net observations report
  60. GRB 220910A: Fermi GBM observation
  61. IPN triangulation of GRB 220910A (bright/long)
  62. GRB 220912A: AstroSat CZTI detection
  63. GRB 220831A: DECam optical counterpart follow-up
  64. GRB 220909A: Swift-XRT observations
  65. GRB 220912A: Fermi GBM Final Real-time Localization
  66. IPN triangulation of GRB 220905A
  67. GRB 220909A: Swift ToO observations
  68. GRB 220909A: Swift/BAT-GUANO candidate arcminute localization
  69. GRB 220831A: Gemini-South Infrared Observations
  70. GRB 220910A: AstroSat CZTI detection
  71. GRB 220910A: AGILE detection
  72. GRB 220909A: Fermi GBM Final Real-time Localization
  73. IceCube-220907A: Upper limits from a search for additional neutrino events in IceCube
  74. GRB 220907A: Swift-BAT refined analysis
  75. IceCube-220907A: One Candidate Counterpart from the Zwicky Transient Facility
  76. GRB 220831A: Gemini-South/GMOS detection of potential optical counterpart
  77. IPN triangulation of GRB 220903A (long)
  78. GRB 220907A: Fermi GBM observation
  79. GRB 220907A: Nanshan/NEXT optical upper limits
  80. GRB 220907A: Swift/UVOT Upper Limits
  81. GRB 220907A: Swift-XRT refined Analysis
  82. GRB 220831A: ATCA 5/9 GHz radio observations
  83. Fermi-LAT Gamma-ray Observations of IceCube-220907A
  84. GRB 220907A: Swift-XRT position
  85. GRB 220907A: Swift detection of a burst
  86. GRB 220907A: Fermi GBM Final Real-time Localization
  87. Swift GRB220907.59: Global MASTER-Net observations report
  88. IceCube-220907A - IceCube observation of a high-energy neutrino candidate track-like event
  89. IceCube Alert 220907.28: Global MASTER-Net observations report
  90. GRB 220831A: Swift-UVOT Upper Limits
  91. Fermi GRB 220905A: Global MASTER-Net observations report
  92. GRB 220905A: BALROG localization (Fermi Trigger 684070128 / GRB 220905478)
  93. GRB 220905A: Fermi GBM Final Real-time Localization
  94. Introducing Self-Service Configuration of GCN Notices over Email for Transient Alerts
  95. GRB 220831A: DECam detection of a possible optical counterpart
  96. Fermi GRB 220902A: Global MASTER-Net observations report
  97. GRB 220902A: Fermi GBM Final Real-time Localization
  98. GRB 220831A, VLT/HAWK-I near-infrared observations
  99. GRB 220831C: Fermi GBM Final Localization
  100. GRB 220831A: Fermi GBM observation

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