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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. SGR 1935+2154: Detection by GRBAlpha
  2. The probability of observing GRB 221009A at z = 0.151
  3. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 October 17
  4. GRB 221009A: Medicina Radio Telescope observations
  5. GRB 221017A: Swift ToO observations
  6. AGILE detection of short X-ray flaring activity contemporary to SGR J1935+2154 reported bursts
  7. GRB 221009A: Second epoch of NuSTAR data
  8. IPN triangulation of GRB 221017A (long)
  9. GRB 221016A: Swift-BAT refined analysis
  10. GRB 221016A: Swift/UVOT Detection
  11. GRB 221016A: Swift-XRT refined Analysis
  12. Konus-Wind detection of GRB 221016A
  13. GRB 221016A: Fermi GBM observation
  14. GRB 220926B: Detection by GRBAlpha
  15. GRB 221009A: A type I BdHN of exceptional energetics
  16. MAXI GRB221017.24: Global MASTER-Net observations report
  17. GRB 221016A: z-band upper limit, possible afterglow brightening
  18. GRB 221017A: MAXI/GSC detection
  19. GRB 221016A: Enhanced Swift-XRT position
  20. GRB 221016A: LCOGT Optical Afterglow Detection
  21. GRB 221016A: Swift detection of a burst
  22. GRB 221016A: Fermi GBM Final Real-time Localization
  23. Swift GRB221016.99: Global MASTER-Net observations report
  24. GRB 221009A: Faulkes Telescope North continued optical afterglow follow-up
  25. Konus-Wind detection of a short burst coincident with a bright radio burst from SGR 1935+2154
  26. GRB 221009A: continued Assy optical afterglow observations, possible SN evidence
  27. Konus-Wind observation of the recent SGR 1935+2154 activity
  28. GRB 221009A: LEIA X-ray Afterglow Detection
  29. GRB 221009A: ATCA radio spectrum
  30. GRB 221009A: VLT spectroscopic detection of the host galaxy
  31. Fermi Gamma-ray Burst Monitor detections of SGR 1935+2154
  32. GRB 221009A: ATCA detection
  33. GRB 221009A: Armchair Energetics
  34. GRB 221009A: ALMA and ACA detections
  35. GRB 221009A: Fermi LAT data rate effects due to extremely high flux
  36. GRB 221009A: Large Binocular Telescope Observatory optical afterglow detection
  37. GRB 221009A: Pan-STARRS optical photometry
  38. GRB 221009A: VLA detection
  39. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  40. GRB 221009A: continued REM optical/NIR observations and evidence for an achromatic steepening in the afterglow light curve
  41. GRB 221009A: IXPE preliminary upper limits of X-ray polarization
  42. GRB 221009A: OHP optical observations
  43. GRB221009A: RTT-150 optical observations
  44. GRB 221009A: HEBS detection
  45. GRB 221009A: Gemini-South Infrared Afterglow Detection
  46. GRB221009A: Gemini-South Optical Afterglow Detection
  47. GRB 221009A: a 397.7 GeV photon observed by Fermi-LAT at 0.4 day after the GBM trigger
  48. GRB 221014A: Fermi GBM Final Real-time Localization
  49. GRB 221009A: Gamma-ray Detection by SIRI-2
  50. GRB221009A: Ionospheric disturbance observed in India
  51. GRB221009A: Detection as sudden ionospheric disturbances (SID)
  52. GRB221009A: RTT-150 optical observations
  53. MAXI GRB 221006A: Redshifts of the possible host galaxies
  54. GRB 221009A: search for neutrinos with KM3NeT
  55. GRB 221009A: MeerKAT detection
  56. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  57. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  58. Fermi Gamma-ray Burst Monitor continues to detect SGR 1935+2154
  59. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  60. Fermi trigger No 687345829: Global MASTER-Net observations report
  61. Fermi trigger No 687344475: Global MASTER-Net observations report
  62. Fermi trigger No 687340841: Global MASTER-Net observations report
  63. Fermi trigger No 687337536: Global MASTER-Net observations report
  64. GRB 221006A: Swift-XRT afterglow detection
  65. GRB 221009A: MITSuME Okayama optical observation
  66. GRB 221009A: Sayan observatory 1.6-m telescope observations
  67. Fermi trigger No 687281393: Global MASTER-Net observations report
  68. GRB 221009A: GMG observation
  69. GRB 221013B: Fermi GBM Final Real-time Localization
  70. Integral GRB221013.04: Global MASTER-Net observations report
  71. GRB 221013A: Fermi GBM Final Real-time Localization
  72. Integral GRB221013.00: Global MASTER-Net observations report
  73. Integral GRB221012.99: Global MASTER-Net observations report
  74. Integral GRB221012.94: Global MASTER-Net observations report
  75. Integral GRB221012.91: Global MASTER-Net observations report
  76. Integral GRB221012.88: Global MASTER-Net observations report
  77. Integral GRB221012.87: Global MASTER-Net observations report
  78. Integral GRB221012.77: Global MASTER-Net observations report
  79. Integral GRB221012.74: Global MASTER-Net observations report
  80. Integral GRB221012.72: Global MASTER-Net observations report
  81. Integral GRB221012.71: Global MASTER-Net observations report
  82. Integral GRB221012.68: Global MASTER-Net observations report
  83. Integral GRB221012.68: Global MASTER-Net observations report
  84. Integral GRB221012.98: Global MASTER-Net observations report
  85. Afterglow limits of GRB 221006A from OHP
  86. GRB221009A: optical afterglow measurements from Konkoly Observatory
  87. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  88. GRB 221009A/Swift J1913.1+1946: SMA observations
  89. INTEGRAL shows increasing activity in SGR J1935+2154
  90. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  91. Integral GRB221012.63: Global MASTER-Net observations report
  92. Integral GRB221012.61: Global MASTER-Net observations report
  93. Integral GRB221012.60: Global MASTER-Net observations report
  94. Integral GRB221012.53: Global MASTER-Net observations report
  95. GRB 221009A/Swift J1913.1+1946: eMERLIN observations
  96. Fermi trigger No 687205006: Global MASTER-Net observations report
  97. INTEGRAL detection of a burst from SGR J1935+2154
  98. GRB 220829A: Detection by GRBAlpha
  99. GRB 220826B: Detection by GRBAlpha
  100. GRB 221009A: NuSTAR Detection

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