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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. Afterglow limits of GRB 221006A from OHP
  2. GRB221009A: optical afterglow measurements from Konkoly Observatory
  3. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  4. GRB 221009A/Swift J1913.1+1946: SMA observations
  5. INTEGRAL shows increasing activity in SGR J1935+2154
  6. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  7. Integral GRB221012.63: Global MASTER-Net observations report
  8. Integral GRB221012.61: Global MASTER-Net observations report
  9. Integral GRB221012.60: Global MASTER-Net observations report
  10. Integral GRB221012.53: Global MASTER-Net observations report
  11. GRB 221009A/Swift J1913.1+1946: eMERLIN observations
  12. Fermi trigger No 687205006: Global MASTER-Net observations report
  13. INTEGRAL detection of a burst from SGR J1935+2154
  14. GRB 220829A: Detection by GRBAlpha
  15. GRB 220826B: Detection by GRBAlpha
  16. GRB 221009A: NuSTAR Detection
  17. GRB 221009A: NICER follow-up observations
  18. GRB 221009A: LCOGT Optical Afterglow Detection
  19. GRB 221009A: COATLI Detection of the Afterglow
  20. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  21. GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
  22. Fermi trigger No 687190301: Global MASTER-Net observations report
  23. GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
  24. Fermi Gamma-ray Burst Monitor trigger 221011452/687178284 is not a GRB
  25. GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
  26. GRB 221009A: Detection by GRBAlpha
  27. GRB 221009A: Sintez-Newton/CrAO optical observations
  28. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  29. GRB 221006A: Swift ToO observations
  30. GRB 221011A: Fermi GBM Final Real-time Localization
  31. Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
  32. GRB 221009A (Swift J1913.1+1946): iTelescope optical observation
  33. GRB 221009A: BlackGEM optical observations
  34. LHAASO observed GRB 221009A with more than 5000 VHE photons up to around 18 TeV
  35. GRB 221009A: NOEMA mm detection
  36. INTEGRAL detection of a burst from SGR J1935+2154
  37. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  38. Integral GRB221010.89: Global MASTER-Net observations report
  39. Fermi trigger No 687077239: Global MASTER-Net observations report
  40. GRB 221009A: Continued Swift/XRT observations
  41. GRB 221009A/Swift J1913.1+1946: Assy optical afterglow observation
  42. GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
  43. Konus-Wind detection of GRB 221009A
  44. GRB 221009A: Lulin SLT-40cm optical observations
  45. Swift J1913.1+1946: New Photometry
  46. GRB 221009A: Upper limits from a neutrino search with IceCube
  47. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  48. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  49. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  50. GRB221009A/Swift J1913.1+1946: Solar Orbiter STIX measurements
  51. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  52. ​GRB 221009A: Multi-color detection of the optical
  53. GRB 221009A: Fermi-LAT refined analysis
  54. GRB 221009A (Swift J1913.1+1946): AGILE/GRID detection
  55. GRB 221009: Swift/UVOT Detection
  56. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  57. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  58. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  59. GRB 221009A: REM optical and NIR detection of the afterglow
  60. GRB 221009A: Swift-XRT refined Analysis
  61. GRB 221009A (Swift J1913.1+1946): AGILE/MCAL detection
  62. Swift J1913.1+1946: Early Optical Photometry
  63. GRB 221009A: Redshift from X-shooter/VLT
  64. GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
  65. GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
  66. GRB 221009A (Swift J1913.1+1946): Mondy optical observations
  67. GRB 221009A BOOTES-2/TELMA and OSN optical detections
  68. Swift J1913.1+1946 : Pre-discovery limits from ZTF
  69. GRB 221009A: Fermi GBM observation
  70. IPN triangulation of extremely bright GRB 221009A
  71. Swift J1913.1+1946: Optical photometry
  72. Fermi trigger No 687014224: Global MASTER-Net observations report
  73. Swift J1913.1+1946: Liverpool Telescope imaging and spectroscopy
  74. GRB 221009A or Swift J1913.1+1946: Fermi-LAT detection
  75. GRB 221009A: Fermi GBM detection of an extraordinarily bright GRB
  76. GRB 221009A: Swift detected transient may be GRB
  77. Swift GRB221009.59: Global MASTER-Net OT detection
  78. GRB 221008A: Swift-XRT observations
  79. Swift J1913.1+1946 a new bright hard X-ray and optical transient
  80. GRB 221008A: Tiled Swift observations
  81. GRB 221008A: MAXI/GSC detection
  82. GRB 220915A: Detection by GRBAlpha
  83. GRB 221006A: Swift-XRT observations
  84. GRB 221006A: Tiled Swift observations
  85. GRB 221006A: MAXI/GSC detection
  86. GRB 2209030A: MITSuME Akeno optical upper limits
  87. GRB 220912A: Detection by VZLUSAT-2
  88. Fermi trigger No 686588176: Global MASTER-Net observations report
  89. GRB220927A: Detection by GRBAlpha
  90. Fermi GBM trigger 686565116/221004355 is not a GRB
  91. Fermi GBM trigger 686435254/221002852 is not a GRB
  92. Fermi GBM trigger 686350260/221001869 is not a GRB
  93. GRB 220921A: ATCA detection of radio counterpart
  94. GRB 220930A: AbAO Optical Upper Limit
  95. Fermi trigger No 686403226: Global MASTER-Net observations report
  96. Fermi trigger No 686350260: Global MASTER-Net observations report
  97. Konus-Wind detection of GRB 220930A
  98. GRB 220930A: AstroSat CZTI detection
  99. GRB 220930A: Swift-BAT refined analysis
  100. GRB 220930A: Swift-XRT refined Analysis

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