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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: Faulkes Telescope North continued optical afterglow follow-up
  2. Konus-Wind detection of a short burst coincident with a bright radio burst from SGR 1935+2154
  3. GRB 221009A: continued Assy optical afterglow observations, possible SN evidence
  4. Konus-Wind observation of the recent SGR 1935+2154 activity
  5. GRB 221009A: LEIA X-ray Afterglow Detection
  6. GRB 221009A: ATCA radio spectrum
  7. GRB 221009A: VLT spectroscopic detection of the host galaxy
  8. Fermi Gamma-ray Burst Monitor detections of SGR 1935+2154
  9. GRB 221009A: ATCA detection
  10. GRB 221009A: Armchair Energetics
  11. GRB 221009A: ALMA and ACA detections
  12. GRB 221009A: Fermi LAT data rate effects due to extremely high flux
  13. GRB 221009A: Large Binocular Telescope Observatory optical afterglow detection
  14. GRB 221009A: Pan-STARRS optical photometry
  15. GRB 221009A: VLA detection
  16. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  17. GRB 221009A: continued REM optical/NIR observations and evidence for an achromatic steepening in the afterglow light curve
  18. GRB 221009A: IXPE preliminary upper limits of X-ray polarization
  19. GRB 221009A: OHP optical observations
  20. GRB221009A: RTT-150 optical observations
  21. GRB 221009A: HEBS detection
  22. GRB 221009A: Gemini-South Infrared Afterglow Detection
  23. GRB221009A: Gemini-South Optical Afterglow Detection
  24. GRB 221009A: a 397.7 GeV photon observed by Fermi-LAT at 0.4 day after the GBM trigger
  25. GRB 221014A: Fermi GBM Final Real-time Localization
  26. GRB 221009A: Gamma-ray Detection by SIRI-2
  27. GRB221009A: Ionospheric disturbance observed in India
  28. GRB221009A: Detection as sudden ionospheric disturbances (SID)
  29. GRB221009A: RTT-150 optical observations
  30. MAXI GRB 221006A: Redshifts of the possible host galaxies
  31. GRB 221009A: search for neutrinos with KM3NeT
  32. GRB 221009A: MeerKAT detection
  33. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  34. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  35. Fermi Gamma-ray Burst Monitor continues to detect SGR 1935+2154
  36. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  37. Fermi trigger No 687345829: Global MASTER-Net observations report
  38. Fermi trigger No 687344475: Global MASTER-Net observations report
  39. Fermi trigger No 687340841: Global MASTER-Net observations report
  40. Fermi trigger No 687337536: Global MASTER-Net observations report
  41. GRB 221006A: Swift-XRT afterglow detection
  42. GRB 221009A: MITSuME Okayama optical observation
  43. GRB 221009A: Sayan observatory 1.6-m telescope observations
  44. Fermi trigger No 687281393: Global MASTER-Net observations report
  45. GRB 221009A: GMG observation
  46. GRB 221013B: Fermi GBM Final Real-time Localization
  47. Integral GRB221013.04: Global MASTER-Net observations report
  48. GRB 221013A: Fermi GBM Final Real-time Localization
  49. Integral GRB221013.00: Global MASTER-Net observations report
  50. Integral GRB221012.99: Global MASTER-Net observations report
  51. Integral GRB221012.94: Global MASTER-Net observations report
  52. Integral GRB221012.91: Global MASTER-Net observations report
  53. Integral GRB221012.88: Global MASTER-Net observations report
  54. Integral GRB221012.87: Global MASTER-Net observations report
  55. Integral GRB221012.77: Global MASTER-Net observations report
  56. Integral GRB221012.74: Global MASTER-Net observations report
  57. Integral GRB221012.72: Global MASTER-Net observations report
  58. Integral GRB221012.71: Global MASTER-Net observations report
  59. Integral GRB221012.68: Global MASTER-Net observations report
  60. Integral GRB221012.68: Global MASTER-Net observations report
  61. Integral GRB221012.98: Global MASTER-Net observations report
  62. Afterglow limits of GRB 221006A from OHP
  63. GRB221009A: optical afterglow measurements from Konkoly Observatory
  64. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  65. GRB 221009A/Swift J1913.1+1946: SMA observations
  66. INTEGRAL shows increasing activity in SGR J1935+2154
  67. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  68. Integral GRB221012.63: Global MASTER-Net observations report
  69. Integral GRB221012.61: Global MASTER-Net observations report
  70. Integral GRB221012.60: Global MASTER-Net observations report
  71. Integral GRB221012.53: Global MASTER-Net observations report
  72. GRB 221009A/Swift J1913.1+1946: eMERLIN observations
  73. Fermi trigger No 687205006: Global MASTER-Net observations report
  74. INTEGRAL detection of a burst from SGR J1935+2154
  75. GRB 220829A: Detection by GRBAlpha
  76. GRB 220826B: Detection by GRBAlpha
  77. GRB 221009A: NuSTAR Detection
  78. GRB 221009A: NICER follow-up observations
  79. GRB 221009A: LCOGT Optical Afterglow Detection
  80. GRB 221009A: COATLI Detection of the Afterglow
  81. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  82. GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
  83. Fermi trigger No 687190301: Global MASTER-Net observations report
  84. GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
  85. Fermi Gamma-ray Burst Monitor trigger 221011452/687178284 is not a GRB
  86. GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
  87. GRB 221009A: Detection by GRBAlpha
  88. GRB 221009A: Sintez-Newton/CrAO optical observations
  89. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  90. GRB 221006A: Swift ToO observations
  91. GRB 221011A: Fermi GBM Final Real-time Localization
  92. Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
  93. GRB 221009A (Swift J1913.1+1946): iTelescope optical observation
  94. GRB 221009A: BlackGEM optical observations
  95. LHAASO observed GRB 221009A with more than 5000 VHE photons up to around 18 TeV
  96. GRB 221009A: NOEMA mm detection
  97. INTEGRAL detection of a burst from SGR J1935+2154
  98. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  99. Integral GRB221010.89: Global MASTER-Net observations report
  100. Fermi trigger No 687077239: Global MASTER-Net observations report

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