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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 J1913.1+1946: New Photometry
  2. GRB 221009A: Upper limits from a neutrino search with IceCube
  3. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  4. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  5. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  6. GRB221009A/Swift J1913.1+1946: Solar Orbiter STIX measurements
  7. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  8. ​GRB 221009A: Multi-color detection of the optical
  9. GRB 221009A: Fermi-LAT refined analysis
  10. GRB 221009A (Swift J1913.1+1946): AGILE/GRID detection
  11. GRB 221009: Swift/UVOT Detection
  12. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  13. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  14. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  15. GRB 221009A: REM optical and NIR detection of the afterglow
  16. GRB 221009A: Swift-XRT refined Analysis
  17. GRB 221009A (Swift J1913.1+1946): AGILE/MCAL detection
  18. Swift J1913.1+1946: Early Optical Photometry
  19. GRB 221009A: Redshift from X-shooter/VLT
  20. GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
  21. GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
  22. GRB 221009A (Swift J1913.1+1946): Mondy optical observations
  23. GRB 221009A BOOTES-2/TELMA and OSN optical detections
  24. Swift J1913.1+1946 : Pre-discovery limits from ZTF
  25. GRB 221009A: Fermi GBM observation
  26. IPN triangulation of extremely bright GRB 221009A
  27. Swift J1913.1+1946: Optical photometry
  28. Fermi trigger No 687014224: Global MASTER-Net observations report
  29. Swift J1913.1+1946: Liverpool Telescope imaging and spectroscopy
  30. GRB 221009A or Swift J1913.1+1946: Fermi-LAT detection
  31. GRB 221009A: Fermi GBM detection of an extraordinarily bright GRB
  32. GRB 221009A: Swift detected transient may be GRB
  33. Swift GRB221009.59: Global MASTER-Net OT detection
  34. GRB 221008A: Swift-XRT observations
  35. Swift J1913.1+1946 a new bright hard X-ray and optical transient
  36. GRB 221008A: Tiled Swift observations
  37. GRB 221008A: MAXI/GSC detection
  38. GRB 220915A: Detection by GRBAlpha
  39. GRB 221006A: Swift-XRT observations
  40. GRB 221006A: Tiled Swift observations
  41. GRB 221006A: MAXI/GSC detection
  42. GRB 2209030A: MITSuME Akeno optical upper limits
  43. GRB 220912A: Detection by VZLUSAT-2
  44. Fermi trigger No 686588176: Global MASTER-Net observations report
  45. GRB220927A: Detection by GRBAlpha
  46. Fermi GBM trigger 686565116/221004355 is not a GRB
  47. Fermi GBM trigger 686435254/221002852 is not a GRB
  48. Fermi GBM trigger 686350260/221001869 is not a GRB
  49. GRB 220921A: ATCA detection of radio counterpart
  50. GRB 220930A: AbAO Optical Upper Limit
  51. Fermi trigger No 686403226: Global MASTER-Net observations report
  52. Fermi trigger No 686350260: Global MASTER-Net observations report
  53. Konus-Wind detection of GRB 220930A
  54. GRB 220930A: AstroSat CZTI detection
  55. GRB 220930A: Swift-BAT refined analysis
  56. GRB 220930A: Swift-XRT refined Analysis
  57. GRB 220930A: LCOGT Optical Upper Limits
  58. GRB 220930A: Swift/UVOT Upper Limits
  59. GRB 220930A: Enhanced Swift-XRT position
  60. Swift GRB 220930A: Global MASTER-Net observations report
  61. GRB 220930A: BOOTES-5/JGT early optical upper limit
  62. GRB 220930A: Prompt enhanced Swift-XRT position
  63. GRB 220930A: COATLI Upper Limits
  64. GRB 220930A: Swift detection of a burst
  65. Fermi-LAT gamma-ray observations of IceCube-220928A
  66. IceCube-220928A: Upper limits from a search for additional neutrino events in IceCube
  67. Konus-Wind detection of GRB 220927A
  68. IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event
  69. Fermi GRB 220927A: Global MASTER-Net observations report
  70. IPN triangulation of GRB 220927A (long)
  71. GRB 220921A: LCOGT Optical Observations
  72. GRB 220611A: Host galaxy redshift from VLT/X-shooter
  73. GRB 220927A: Fermi GBM Final Localization
  74. GRB 220924A: Fermi GBM detection
  75. Integral GRB220926.44: Global MASTER-Net observations report
  76. Ultra-long GRB 220525B: Konus-Wind and Fermi-GBM detection
  77. Swift Trigger 1125354 (GRB 220926A) is not a GRB
  78. Swift GRB220926.34: Global MASTER-Net observations report
  79. Swift GRB 220926A: Global MASTER-Net observations report
  80. Analysis of long GRB 220926B detected by INTEGRAL
  81. GRB 220926B
  82. GRB 220926A: Swift detection of a burst
  83. Fermi GRB 220925A: Global MASTER-Net observations report
  84. GRB 220924A: Swift/BAT-GUANO detection outside the coded FOV
  85. GRB 220921A: further MeerLICHT observations
  86. GRB 220925A: Fermi GBM Final Real-time Localization
  87. Fermi trigger No 685748699: Global MASTER-Net observations report
  88. GRB 220924A: Fermi GBM Final Real-time Localization
  89. Swift GRB220923.47: Global MASTER-Net observations report
  90. GRB 220921A: ALMA detection
  91. GRB 220921A: DDOTI Detection of the Afterglow
  92. Konus-Wind detection of GRB 220921A
  93. GRB 220921A: Fermi GBM detection
  94. IceCube-220907A: Classification of AT2022oyn as a Type Ia supernova
  95. GRB 220921A: MeerLICHT afterglow observations
  96. GRB 220921A: Swift-XRT Observations
  97. GRB 220921A: MASTER OT inside Fermi-LAT error-box
  98. LAT GRB220921.46: Global MASTER-Net observations report
  99. GRB 220921A: Fermi-LAT detection
  100. GRB 220921A: Tiled Swift observations

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