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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 (Swift J1913.1+1946): Swift-BAT refined analysis
  2. Fermi Gamma-ray Burst Monitor trigger 221011452/687178284 is not a GRB
  3. GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
  4. GRB 221009A: Detection by GRBAlpha
  5. GRB 221009A: Sintez-Newton/CrAO optical observations
  6. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  7. GRB 221006A: Swift ToO observations
  8. GRB 221011A: Fermi GBM Final Real-time Localization
  9. Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
  10. GRB 221009A (Swift J1913.1+1946): iTelescope optical observation
  11. GRB 221009A: BlackGEM optical observations
  12. LHAASO observed GRB 221009A with more than 5000 VHE photons up to around 18 TeV
  13. GRB 221009A: NOEMA mm detection
  14. INTEGRAL detection of a burst from SGR J1935+2154
  15. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  16. Integral GRB221010.89: Global MASTER-Net observations report
  17. Fermi trigger No 687077239: Global MASTER-Net observations report
  18. GRB 221009A: Continued Swift/XRT observations
  19. GRB 221009A/Swift J1913.1+1946: Assy optical afterglow observation
  20. GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
  21. Konus-Wind detection of GRB 221009A
  22. GRB 221009A: Lulin SLT-40cm optical observations
  23. Swift J1913.1+1946: New Photometry
  24. GRB 221009A: Upper limits from a neutrino search with IceCube
  25. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  26. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  27. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  28. GRB221009A/Swift J1913.1+1946: Solar Orbiter STIX measurements
  29. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  30. ​GRB 221009A: Multi-color detection of the optical
  31. GRB 221009A: Fermi-LAT refined analysis
  32. GRB 221009A (Swift J1913.1+1946): AGILE/GRID detection
  33. GRB 221009: Swift/UVOT Detection
  34. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  35. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  36. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  37. GRB 221009A: REM optical and NIR detection of the afterglow
  38. GRB 221009A: Swift-XRT refined Analysis
  39. GRB 221009A (Swift J1913.1+1946): AGILE/MCAL detection
  40. Swift J1913.1+1946: Early Optical Photometry
  41. GRB 221009A: Redshift from X-shooter/VLT
  42. GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
  43. GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
  44. GRB 221009A (Swift J1913.1+1946): Mondy optical observations
  45. GRB 221009A BOOTES-2/TELMA and OSN optical detections
  46. Swift J1913.1+1946 : Pre-discovery limits from ZTF
  47. GRB 221009A: Fermi GBM observation
  48. IPN triangulation of extremely bright GRB 221009A
  49. Swift J1913.1+1946: Optical photometry
  50. Fermi trigger No 687014224: Global MASTER-Net observations report
  51. Swift J1913.1+1946: Liverpool Telescope imaging and spectroscopy
  52. GRB 221009A or Swift J1913.1+1946: Fermi-LAT detection
  53. GRB 221009A: Fermi GBM detection of an extraordinarily bright GRB
  54. GRB 221009A: Swift detected transient may be GRB
  55. Swift GRB221009.59: Global MASTER-Net OT detection
  56. GRB 221008A: Swift-XRT observations
  57. Swift J1913.1+1946 a new bright hard X-ray and optical transient
  58. GRB 221008A: Tiled Swift observations
  59. GRB 221008A: MAXI/GSC detection
  60. GRB 220915A: Detection by GRBAlpha
  61. GRB 221006A: Swift-XRT observations
  62. GRB 221006A: Tiled Swift observations
  63. GRB 221006A: MAXI/GSC detection
  64. GRB 2209030A: MITSuME Akeno optical upper limits
  65. GRB 220912A: Detection by VZLUSAT-2
  66. Fermi trigger No 686588176: Global MASTER-Net observations report
  67. GRB220927A: Detection by GRBAlpha
  68. Fermi GBM trigger 686565116/221004355 is not a GRB
  69. Fermi GBM trigger 686435254/221002852 is not a GRB
  70. Fermi GBM trigger 686350260/221001869 is not a GRB
  71. GRB 220921A: ATCA detection of radio counterpart
  72. GRB 220930A: AbAO Optical Upper Limit
  73. Fermi trigger No 686403226: Global MASTER-Net observations report
  74. Fermi trigger No 686350260: Global MASTER-Net observations report
  75. Konus-Wind detection of GRB 220930A
  76. GRB 220930A: AstroSat CZTI detection
  77. GRB 220930A: Swift-BAT refined analysis
  78. GRB 220930A: Swift-XRT refined Analysis
  79. GRB 220930A: LCOGT Optical Upper Limits
  80. GRB 220930A: Swift/UVOT Upper Limits
  81. GRB 220930A: Enhanced Swift-XRT position
  82. Swift GRB 220930A: Global MASTER-Net observations report
  83. GRB 220930A: BOOTES-5/JGT early optical upper limit
  84. GRB 220930A: Prompt enhanced Swift-XRT position
  85. GRB 220930A: COATLI Upper Limits
  86. GRB 220930A: Swift detection of a burst
  87. Fermi-LAT gamma-ray observations of IceCube-220928A
  88. IceCube-220928A: Upper limits from a search for additional neutrino events in IceCube
  89. Konus-Wind detection of GRB 220927A
  90. IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event
  91. Fermi GRB 220927A: Global MASTER-Net observations report
  92. IPN triangulation of GRB 220927A (long)
  93. GRB 220921A: LCOGT Optical Observations
  94. GRB 220611A: Host galaxy redshift from VLT/X-shooter
  95. GRB 220927A: Fermi GBM Final Localization
  96. GRB 220924A: Fermi GBM detection
  97. Integral GRB220926.44: Global MASTER-Net observations report
  98. Ultra-long GRB 220525B: Konus-Wind and Fermi-GBM detection
  99. Swift Trigger 1125354 (GRB 220926A) is not a GRB
  100. Swift GRB220926.34: Global MASTER-Net observations report

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