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

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