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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').
  1. GRB 221009A: Second epoch of NuSTAR data
  2. IPN triangulation of GRB 221017A (long)
  3. GRB 221016A: Swift-BAT refined analysis
  4. GRB 221016A: Swift/UVOT Detection
  5. GRB 221016A: Swift-XRT refined Analysis
  6. Konus-Wind detection of GRB 221016A
  7. GRB 221016A: Fermi GBM observation
  8. GRB 220926B: Detection by GRBAlpha
  9. GRB 221009A: A type I BdHN of exceptional energetics
  10. MAXI GRB221017.24: Global MASTER-Net observations report
  11. GRB 221016A: z-band upper limit, possible afterglow brightening
  12. GRB 221017A: MAXI/GSC detection
  13. GRB 221016A: Enhanced Swift-XRT position
  14. GRB 221016A: LCOGT Optical Afterglow Detection
  15. GRB 221016A: Swift detection of a burst
  16. GRB 221016A: Fermi GBM Final Real-time Localization
  17. Swift GRB221016.99: Global MASTER-Net observations report
  18. GRB 221009A: Faulkes Telescope North continued optical afterglow follow-up
  19. Konus-Wind detection of a short burst coincident with a bright radio burst from SGR 1935+2154
  20. GRB 221009A: continued Assy optical afterglow observations, possible SN evidence
  21. Konus-Wind observation of the recent SGR 1935+2154 activity
  22. GRB 221009A: LEIA X-ray Afterglow Detection
  23. GRB 221009A: ATCA radio spectrum
  24. GRB 221009A: VLT spectroscopic detection of the host galaxy
  25. Fermi Gamma-ray Burst Monitor detections of SGR 1935+2154
  26. GRB 221009A: ATCA detection
  27. GRB 221009A: Armchair Energetics
  28. GRB 221009A: ALMA and ACA detections
  29. GRB 221009A: Fermi LAT data rate effects due to extremely high flux
  30. GRB 221009A: Large Binocular Telescope Observatory optical afterglow detection
  31. GRB 221009A: Pan-STARRS optical photometry
  32. GRB 221009A: VLA detection
  33. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  34. GRB 221009A: continued REM optical/NIR observations and evidence for an achromatic steepening in the afterglow light curve
  35. GRB 221009A: IXPE preliminary upper limits of X-ray polarization
  36. GRB 221009A: OHP optical observations
  37. GRB221009A: RTT-150 optical observations
  38. GRB 221009A: HEBS detection
  39. GRB 221009A: Gemini-South Infrared Afterglow Detection
  40. GRB221009A: Gemini-South Optical Afterglow Detection
  41. GRB 221009A: a 397.7 GeV photon observed by Fermi-LAT at 0.4 day after the GBM trigger
  42. GRB 221014A: Fermi GBM Final Real-time Localization
  43. GRB 221009A: Gamma-ray Detection by SIRI-2
  44. GRB221009A: Ionospheric disturbance observed in India
  45. GRB221009A: Detection as sudden ionospheric disturbances (SID)
  46. GRB221009A: RTT-150 optical observations
  47. MAXI GRB 221006A: Redshifts of the possible host galaxies
  48. GRB 221009A: search for neutrinos with KM3NeT
  49. GRB 221009A: MeerKAT detection
  50. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  51. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  52. Fermi Gamma-ray Burst Monitor continues to detect SGR 1935+2154
  53. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  54. Fermi trigger No 687345829: Global MASTER-Net observations report
  55. Fermi trigger No 687344475: Global MASTER-Net observations report
  56. Fermi trigger No 687340841: Global MASTER-Net observations report
  57. Fermi trigger No 687337536: Global MASTER-Net observations report
  58. GRB 221006A: Swift-XRT afterglow detection
  59. GRB 221009A: MITSuME Okayama optical observation
  60. GRB 221009A: Sayan observatory 1.6-m telescope observations
  61. Fermi trigger No 687281393: Global MASTER-Net observations report
  62. GRB 221009A: GMG observation
  63. GRB 221013B: Fermi GBM Final Real-time Localization
  64. Integral GRB221013.04: Global MASTER-Net observations report
  65. GRB 221013A: Fermi GBM Final Real-time Localization
  66. Integral GRB221013.00: Global MASTER-Net observations report
  67. Integral GRB221012.99: Global MASTER-Net observations report
  68. Integral GRB221012.94: Global MASTER-Net observations report
  69. Integral GRB221012.91: Global MASTER-Net observations report
  70. Integral GRB221012.88: Global MASTER-Net observations report
  71. Integral GRB221012.87: Global MASTER-Net observations report
  72. Integral GRB221012.77: Global MASTER-Net observations report
  73. Integral GRB221012.74: Global MASTER-Net observations report
  74. Integral GRB221012.72: Global MASTER-Net observations report
  75. Integral GRB221012.71: Global MASTER-Net observations report
  76. Integral GRB221012.68: Global MASTER-Net observations report
  77. Integral GRB221012.68: Global MASTER-Net observations report
  78. Integral GRB221012.98: Global MASTER-Net observations report
  79. Afterglow limits of GRB 221006A from OHP
  80. GRB221009A: optical afterglow measurements from Konkoly Observatory
  81. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  82. GRB 221009A/Swift J1913.1+1946: SMA observations
  83. INTEGRAL shows increasing activity in SGR J1935+2154
  84. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  85. Integral GRB221012.63: Global MASTER-Net observations report
  86. Integral GRB221012.61: Global MASTER-Net observations report
  87. Integral GRB221012.60: Global MASTER-Net observations report
  88. Integral GRB221012.53: Global MASTER-Net observations report
  89. GRB 221009A/Swift J1913.1+1946: eMERLIN observations
  90. Fermi trigger No 687205006: Global MASTER-Net observations report
  91. INTEGRAL detection of a burst from SGR J1935+2154
  92. GRB 220829A: Detection by GRBAlpha
  93. GRB 220826B: Detection by GRBAlpha
  94. GRB 221009A: NuSTAR Detection
  95. GRB 221009A: NICER follow-up observations
  96. GRB 221009A: LCOGT Optical Afterglow Detection
  97. GRB 221009A: COATLI Detection of the Afterglow
  98. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  99. GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
  100. Fermi trigger No 687190301: Global MASTER-Net observations report

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