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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. GRB221009A: Gemini-South Optical Afterglow Detection
  2. GRB 221009A: a 397.7 GeV photon observed by Fermi-LAT at 0.4 day after the GBM trigger
  3. GRB 221014A: Fermi GBM Final Real-time Localization
  4. GRB 221009A: Gamma-ray Detection by SIRI-2
  5. GRB221009A: Ionospheric disturbance observed in India
  6. GRB221009A: Detection as sudden ionospheric disturbances (SID)
  7. GRB221009A: RTT-150 optical observations
  8. MAXI GRB 221006A: Redshifts of the possible host galaxies
  9. GRB 221009A: search for neutrinos with KM3NeT
  10. GRB 221009A: MeerKAT detection
  11. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  12. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  13. Fermi Gamma-ray Burst Monitor continues to detect SGR 1935+2154
  14. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  15. Fermi trigger No 687345829: Global MASTER-Net observations report
  16. Fermi trigger No 687344475: Global MASTER-Net observations report
  17. Fermi trigger No 687340841: Global MASTER-Net observations report
  18. Fermi trigger No 687337536: Global MASTER-Net observations report
  19. GRB 221006A: Swift-XRT afterglow detection
  20. GRB 221009A: MITSuME Okayama optical observation
  21. GRB 221009A: Sayan observatory 1.6-m telescope observations
  22. Fermi trigger No 687281393: Global MASTER-Net observations report
  23. GRB 221009A: GMG observation
  24. GRB 221013B: Fermi GBM Final Real-time Localization
  25. Integral GRB221013.04: Global MASTER-Net observations report
  26. GRB 221013A: Fermi GBM Final Real-time Localization
  27. Integral GRB221013.00: Global MASTER-Net observations report
  28. Integral GRB221012.99: Global MASTER-Net observations report
  29. Integral GRB221012.94: Global MASTER-Net observations report
  30. Integral GRB221012.91: Global MASTER-Net observations report
  31. Integral GRB221012.88: Global MASTER-Net observations report
  32. Integral GRB221012.87: Global MASTER-Net observations report
  33. Integral GRB221012.77: Global MASTER-Net observations report
  34. Integral GRB221012.74: Global MASTER-Net observations report
  35. Integral GRB221012.72: Global MASTER-Net observations report
  36. Integral GRB221012.71: Global MASTER-Net observations report
  37. Integral GRB221012.68: Global MASTER-Net observations report
  38. Integral GRB221012.68: Global MASTER-Net observations report
  39. Integral GRB221012.98: Global MASTER-Net observations report
  40. Afterglow limits of GRB 221006A from OHP
  41. GRB221009A: optical afterglow measurements from Konkoly Observatory
  42. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  43. GRB 221009A/Swift J1913.1+1946: SMA observations
  44. INTEGRAL shows increasing activity in SGR J1935+2154
  45. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  46. Integral GRB221012.63: Global MASTER-Net observations report
  47. Integral GRB221012.61: Global MASTER-Net observations report
  48. Integral GRB221012.60: Global MASTER-Net observations report
  49. Integral GRB221012.53: Global MASTER-Net observations report
  50. GRB 221009A/Swift J1913.1+1946: eMERLIN observations
  51. Fermi trigger No 687205006: Global MASTER-Net observations report
  52. INTEGRAL detection of a burst from SGR J1935+2154
  53. GRB 220829A: Detection by GRBAlpha
  54. GRB 220826B: Detection by GRBAlpha
  55. GRB 221009A: NuSTAR Detection
  56. GRB 221009A: NICER follow-up observations
  57. GRB 221009A: LCOGT Optical Afterglow Detection
  58. GRB 221009A: COATLI Detection of the Afterglow
  59. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  60. GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
  61. Fermi trigger No 687190301: Global MASTER-Net observations report
  62. GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
  63. Fermi Gamma-ray Burst Monitor trigger 221011452/687178284 is not a GRB
  64. GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
  65. GRB 221009A: Detection by GRBAlpha
  66. GRB 221009A: Sintez-Newton/CrAO optical observations
  67. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  68. GRB 221006A: Swift ToO observations
  69. GRB 221011A: Fermi GBM Final Real-time Localization
  70. Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
  71. GRB 221009A (Swift J1913.1+1946): iTelescope optical observation
  72. GRB 221009A: BlackGEM optical observations
  73. LHAASO observed GRB 221009A with more than 5000 VHE photons up to around 18 TeV
  74. GRB 221009A: NOEMA mm detection
  75. INTEGRAL detection of a burst from SGR J1935+2154
  76. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  77. Integral GRB221010.89: Global MASTER-Net observations report
  78. Fermi trigger No 687077239: Global MASTER-Net observations report
  79. GRB 221009A: Continued Swift/XRT observations
  80. GRB 221009A/Swift J1913.1+1946: Assy optical afterglow observation
  81. GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
  82. Konus-Wind detection of GRB 221009A
  83. GRB 221009A: Lulin SLT-40cm optical observations
  84. Swift J1913.1+1946: New Photometry
  85. GRB 221009A: Upper limits from a neutrino search with IceCube
  86. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  87. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  88. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  89. GRB221009A/Swift J1913.1+1946: Solar Orbiter STIX measurements
  90. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  91. ​GRB 221009A: Multi-color detection of the optical
  92. GRB 221009A: Fermi-LAT refined analysis
  93. GRB 221009A (Swift J1913.1+1946): AGILE/GRID detection
  94. GRB 221009: Swift/UVOT Detection
  95. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  96. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  97. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  98. GRB 221009A: REM optical and NIR detection of the afterglow
  99. GRB 221009A: Swift-XRT refined Analysis
  100. GRB 221009A (Swift J1913.1+1946): AGILE/MCAL detection

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