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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"

30504 results found.

  1. GRB 221009A: LEIA X-ray Afterglow Detection
  2. GRB 221009A: ATCA radio spectrum
  3. GRB 221009A: VLT spectroscopic detection of the host galaxy
  4. Fermi Gamma-ray Burst Monitor detections of SGR 1935+2154
  5. GRB 221009A: ATCA detection
  6. GRB 221009A: Armchair Energetics
  7. GRB 221009A: ALMA and ACA detections
  8. GRB 221009A: Fermi LAT data rate effects due to extremely high flux
  9. GRB 221009A: Large Binocular Telescope Observatory optical afterglow detection
  10. GRB 221009A: Pan-STARRS optical photometry
  11. GRB 221009A: VLA detection
  12. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  13. GRB 221009A: continued REM optical/NIR observations and evidence for an achromatic steepening in the afterglow light curve
  14. GRB 221009A: OHP optical observations
  15. GRB221009A: RTT-150 optical observations
  16. GRB 221009A: HEBS detection
  17. GRB 221009A: Gemini-South Infrared Afterglow Detection
  18. GRB221009A: Gemini-South Optical Afterglow Detection
  19. GRB 221009A: a 397.7 GeV photon observed by Fermi-LAT at 0.4 day after the GBM trigger
  20. GRB 221009A: Gamma-ray Detection by SIRI-2
  21. GRB221009A: Detection as sudden ionospheric disturbances (SID)
  22. GRB221009A: RTT-150 optical observations
  23. MAXI GRB 221006A: Redshifts of the possible host galaxies
  24. GRB 221009A: search for neutrinos with KM3NeT
  25. GRB 221009A: MeerKAT detection
  26. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  27. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  28. Fermi Gamma-ray Burst Monitor continues to detect SGR 1935+2154
  29. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  30. GRB 221006A: Swift-XRT afterglow detection
  31. GRB 221009A: MITSuME Okayama optical observation
  32. GRB 221009A: Sayan observatory 1.6-m telescope observations
  33. GRB 221009A: GMG observation
  34. Afterglow limits of GRB 221006A from OHP
  35. GRB221009A: optical afterglow measurements from Konkoly Observatory
  36. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  37. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  38. INTEGRAL detection of a burst from SGR J1935+2154
  39. GRB 221009A: NuSTAR Detection
  40. GRB 221009A: NICER follow-up observations
  41. GRB 221009A: LCOGT Optical Afterglow Detection
  42. GRB 221009A: COATLI Detection of the Afterglow
  43. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  44. GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
  45. GRB 221009A: Detection by GRBAlpha
  46. GRB 221009A: Sintez-Newton/CrAO optical observations
  47. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  48. GRB 221006A: Swift ToO observations
  49. Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
  50. GRB 221009A (Swift J1913.1+1946): iTelescope optical observation
  51. GRB 221009A: BlackGEM optical observations
  52. LHAASO observed GRB 221009A with more than 5000 VHE photons up to around 18 TeV
  53. GRB 221009A: NOEMA mm detection
  54. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  55. GRB 221009A: Continued Swift/XRT observations
  56. GRB 221009A/Swift J1913.1+1946: Assy optical afterglow observation
  57. GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
  58. Konus-Wind detection of GRB 221009A
  59. GRB 221009A: Lulin SLT-40cm optical observations
  60. Swift J1913.1+1946: New Photometry
  61. GRB 221009A: Upper limits from a neutrino search with IceCube
  62. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  63. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  64. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  65. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  66. ​GRB 221009A: Multi-color detection of the optical
  67. GRB 221009A: Fermi-LAT refined analysis
  68. GRB 221009A (Swift J1913.1+1946): AGILE/GRID detection
  69. GRB 221009: Swift/UVOT Detection
  70. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  71. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  72. GRB 221009A: REM optical and NIR detection of the afterglow
  73. GRB 221009A: Swift-XRT refined Analysis
  74. GRB 221009A (Swift J1913.1+1946): AGILE/MCAL detection
  75. Swift J1913.1+1946: Early Optical Photometry
  76. GRB 221009A: Redshift from X-shooter/VLT
  77. GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
  78. GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
  79. GRB 221009A (Swift J1913.1+1946): Mondy optical observations
  80. Swift J1913.1+1946 : Pre-discovery limits from ZTF
  81. GRB 221009A: Fermi GBM observation
  82. IPN triangulation of extremely bright GRB 221009A
  83. Swift J1913.1+1946: Optical photometry
  84. Swift J1913.1+1946: Liverpool Telescope imaging and spectroscopy
  85. GRB 221009A or Swift J1913.1+1946: Fermi-LAT detection
  86. GRB 221009A: Fermi GBM detection of an extraordinarily bright GRB
  87. GRB 221009A: Swift detected transient may be GRB
  88. GRB 221008A: Swift-XRT observations
  89. GRB 221008A: Tiled Swift observations
  90. GRB 221006A: Swift-XRT observations
  91. GRB 221006A: Tiled Swift observations
  92. GRB 220930A: MITSuME Akeno optical upper limits
  93. GRB 220912A: Detection by VZLUSAT-2
  94. GRB220927A: Detection by GRBAlpha
  95. GRB 220921A: ATCA detection of radio counterpart
  96. GRB 220930A: AbAO Optical Upper Limit
  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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