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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: NICER follow-up observations
  2. GRB 221009A: LCOGT Optical Afterglow Detection
  3. GRB 221009A: COATLI Detection of the Afterglow
  4. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  5. GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
  6. Fermi trigger No 687190301: Global MASTER-Net observations report
  7. GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
  8. Fermi Gamma-ray Burst Monitor trigger 221011452/687178284 is not a GRB
  9. GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
  10. GRB 221009A: Detection by GRBAlpha
  11. GRB 221009A: Sintez-Newton/CrAO optical observations
  12. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  13. GRB 221006A: Swift ToO observations
  14. GRB 221011A: Fermi GBM Final Real-time Localization
  15. Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
  16. GRB 221009A (Swift J1913.1+1946): iTelescope optical observation
  17. GRB 221009A: BlackGEM optical observations
  18. LHAASO observed GRB 221009A with more than 5000 VHE photons up to around 18 TeV
  19. GRB 221009A: NOEMA mm detection
  20. INTEGRAL detection of a burst from SGR J1935+2154
  21. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  22. Integral GRB221010.89: Global MASTER-Net observations report
  23. Fermi trigger No 687077239: Global MASTER-Net observations report
  24. GRB 221009A: Continued Swift/XRT observations
  25. GRB 221009A/Swift J1913.1+1946: Assy optical afterglow observation
  26. GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
  27. Konus-Wind detection of GRB 221009A
  28. GRB 221009A: Lulin SLT-40cm optical observations
  29. Swift J1913.1+1946: New Photometry
  30. GRB 221009A: Upper limits from a neutrino search with IceCube
  31. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  32. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  33. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  34. GRB221009A/Swift J1913.1+1946: Solar Orbiter STIX measurements
  35. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  36. ​GRB 221009A: Multi-color detection of the optical
  37. GRB 221009A: Fermi-LAT refined analysis
  38. GRB 221009A (Swift J1913.1+1946): AGILE/GRID detection
  39. GRB 221009: Swift/UVOT Detection
  40. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  41. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  42. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  43. GRB 221009A: REM optical and NIR detection of the afterglow
  44. GRB 221009A: Swift-XRT refined Analysis
  45. GRB 221009A (Swift J1913.1+1946): AGILE/MCAL detection
  46. Swift J1913.1+1946: Early Optical Photometry
  47. GRB 221009A: Redshift from X-shooter/VLT
  48. GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
  49. GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
  50. GRB 221009A (Swift J1913.1+1946): Mondy optical observations
  51. GRB 221009A BOOTES-2/TELMA and OSN optical detections
  52. Swift J1913.1+1946 : Pre-discovery limits from ZTF
  53. GRB 221009A: Fermi GBM observation
  54. IPN triangulation of extremely bright GRB 221009A
  55. Swift J1913.1+1946: Optical photometry
  56. Fermi trigger No 687014224: Global MASTER-Net observations report
  57. Swift J1913.1+1946: Liverpool Telescope imaging and spectroscopy
  58. GRB 221009A or Swift J1913.1+1946: Fermi-LAT detection
  59. GRB 221009A: Fermi GBM detection of an extraordinarily bright GRB
  60. GRB 221009A: Swift detected transient may be GRB
  61. Swift GRB221009.59: Global MASTER-Net OT detection
  62. GRB 221008A: Swift-XRT observations
  63. Swift J1913.1+1946 a new bright hard X-ray and optical transient
  64. GRB 221008A: Tiled Swift observations
  65. GRB 221008A: MAXI/GSC detection
  66. GRB 220915A: Detection by GRBAlpha
  67. GRB 221006A: Swift-XRT observations
  68. GRB 221006A: Tiled Swift observations
  69. GRB 221006A: MAXI/GSC detection
  70. GRB 2209030A: MITSuME Akeno optical upper limits
  71. GRB 220912A: Detection by VZLUSAT-2
  72. Fermi trigger No 686588176: Global MASTER-Net observations report
  73. GRB220927A: Detection by GRBAlpha
  74. Fermi GBM trigger 686565116/221004355 is not a GRB
  75. Fermi GBM trigger 686435254/221002852 is not a GRB
  76. Fermi GBM trigger 686350260/221001869 is not a GRB
  77. GRB 220921A: ATCA detection of radio counterpart
  78. GRB 220930A: AbAO Optical Upper Limit
  79. Fermi trigger No 686403226: Global MASTER-Net observations report
  80. Fermi trigger No 686350260: Global MASTER-Net observations report
  81. Konus-Wind detection of GRB 220930A
  82. GRB 220930A: AstroSat CZTI detection
  83. GRB 220930A: Swift-BAT refined analysis
  84. GRB 220930A: Swift-XRT refined Analysis
  85. GRB 220930A: LCOGT Optical Upper Limits
  86. GRB 220930A: Swift/UVOT Upper Limits
  87. GRB 220930A: Enhanced Swift-XRT position
  88. Swift GRB 220930A: Global MASTER-Net observations report
  89. GRB 220930A: BOOTES-5/JGT early optical upper limit
  90. GRB 220930A: Prompt enhanced Swift-XRT position
  91. GRB 220930A: COATLI Upper Limits
  92. GRB 220930A: Swift detection of a burst
  93. Fermi-LAT gamma-ray observations of IceCube-220928A
  94. IceCube-220928A: Upper limits from a search for additional neutrino events in IceCube
  95. Konus-Wind detection of GRB 220927A
  96. IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event
  97. Fermi GRB 220927A: Global MASTER-Net observations report
  98. IPN triangulation of GRB 220927A (long)
  99. GRB 220921A: LCOGT Optical Observations
  100. GRB 220611A: Host galaxy redshift from VLT/X-shooter

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