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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').
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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 221021A: Fermi GBM Final Real-time Localization
  2. GRB 221009A: 1.3m DFOT Optical Observations
  3. Fermi GBM trigger 687320613 / 221013100 (GRB 221013B) is not a GRB
  4. GRB221009A: LBT optical imaging
  5. GRB 221009A: Peak luminosity of the supernova vs. synchrotron afterglow
  6. GRB 221017A: Swift-XRT observations
  7. GRB 221020A: Fermi GBM Final Real-time Localization
  8. Improved IPN localization for GRB 221009A (BepiColombo-MGNS light curve)
  9. GRB 221009A: TNG NIR detection
  10. GRB 221009A: BOAO NIR detections
  11. GRB 221009A X-ray light-curve and the indication of TeV light-curve
  12. AGILE detection of a burst from SGR J1935+2154 reported by VZLUSAT-2
  13. GRB 221009A: Spectroscopic detection of emerging SN features
  14. GRB 221009A: Continued LDT Afterglow Monitoring
  15. GRB 221013B: Swift/BAT-GUANO detection
  16. SGR 1935+2154: Bursting activity detected by VZLUSAT-2
  17. AGILE detection of the 2022 October 17 burst from SGR J1935+2154 reported by Konus-Wind
  18. GRB 221009A: GRANDMA observations
  19. SGR 1935+2154: Detection by GRBAlpha
  20. The probability of observing GRB 221009A at z = 0.151
  21. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 October 17
  22. GRB 221009A: Medicina Radio Telescope observations
  23. GRB 221017A: Swift ToO observations
  24. AGILE detection of short X-ray flaring activity contemporary to SGR J1935+2154 reported bursts
  25. GRB 221009A: Second epoch of NuSTAR data
  26. IPN triangulation of GRB 221017A (long)
  27. GRB 221016A: Swift-BAT refined analysis
  28. GRB 221016A: Swift/UVOT Detection
  29. GRB 221016A: Swift-XRT refined Analysis
  30. Konus-Wind detection of GRB 221016A
  31. GRB 221016A: Fermi GBM observation
  32. GRB 220926B: Detection by GRBAlpha
  33. GRB 221009A: A type I BdHN of exceptional energetics
  34. MAXI GRB221017.24: Global MASTER-Net observations report
  35. GRB 221016A: z-band upper limit, possible afterglow brightening
  36. GRB 221017A: MAXI/GSC detection
  37. GRB 221016A: Enhanced Swift-XRT position
  38. GRB 221016A: LCOGT Optical Afterglow Detection
  39. GRB 221016A: Swift detection of a burst
  40. GRB 221016A: Fermi GBM Final Real-time Localization
  41. Swift GRB221016.99: Global MASTER-Net observations report
  42. GRB 221009A: Faulkes Telescope North continued optical afterglow follow-up
  43. Konus-Wind detection of a short burst coincident with a bright radio burst from SGR 1935+2154
  44. GRB 221009A: continued Assy optical afterglow observations, possible SN evidence
  45. Konus-Wind observation of the recent SGR 1935+2154 activity
  46. GRB 221009A: LEIA X-ray Afterglow Detection
  47. GRB 221009A: ATCA radio spectrum
  48. GRB 221009A: VLT spectroscopic detection of the host galaxy
  49. Fermi Gamma-ray Burst Monitor detections of SGR 1935+2154
  50. GRB 221009A: ATCA detection
  51. GRB 221009A: Armchair Energetics
  52. GRB 221009A: ALMA and ACA detections
  53. GRB 221009A: Fermi LAT data rate effects due to extremely high flux
  54. GRB 221009A: Large Binocular Telescope Observatory optical afterglow detection
  55. GRB 221009A: Pan-STARRS optical photometry
  56. GRB 221009A: VLA detection
  57. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  58. GRB 221009A: continued REM optical/NIR observations and evidence for an achromatic steepening in the afterglow light curve
  59. GRB 221009A: IXPE preliminary upper limits of X-ray polarization
  60. GRB 221009A: OHP optical observations
  61. GRB221009A: RTT-150 optical observations
  62. GRB 221009A: HEBS detection
  63. GRB 221009A: Gemini-South Infrared Afterglow Detection
  64. GRB221009A: Gemini-South Optical Afterglow Detection
  65. GRB 221009A: a 397.7 GeV photon observed by Fermi-LAT at 0.4 day after the GBM trigger
  66. GRB 221014A: Fermi GBM Final Real-time Localization
  67. GRB 221009A: Gamma-ray Detection by SIRI-2
  68. GRB221009A: Ionospheric disturbance observed in India
  69. GRB221009A: Detection as sudden ionospheric disturbances (SID)
  70. GRB221009A: RTT-150 optical observations
  71. MAXI GRB 221006A: Redshifts of the possible host galaxies
  72. GRB 221009A: search for neutrinos with KM3NeT
  73. GRB 221009A: MeerKAT detection
  74. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  75. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  76. Fermi Gamma-ray Burst Monitor continues to detect SGR 1935+2154
  77. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  78. Fermi trigger No 687345829: Global MASTER-Net observations report
  79. Fermi trigger No 687344475: Global MASTER-Net observations report
  80. Fermi trigger No 687340841: Global MASTER-Net observations report
  81. Fermi trigger No 687337536: Global MASTER-Net observations report
  82. GRB 221006A: Swift-XRT afterglow detection
  83. GRB 221009A: MITSuME Okayama optical observation
  84. GRB 221009A: Sayan observatory 1.6-m telescope observations
  85. Fermi trigger No 687281393: Global MASTER-Net observations report
  86. GRB 221009A: GMG observation
  87. GRB 221013B: Fermi GBM Final Real-time Localization
  88. Integral GRB221013.04: Global MASTER-Net observations report
  89. GRB 221013A: Fermi GBM Final Real-time Localization
  90. Integral GRB221013.00: Global MASTER-Net observations report
  91. Integral GRB221012.99: Global MASTER-Net observations report
  92. Integral GRB221012.94: Global MASTER-Net observations report
  93. Integral GRB221012.91: Global MASTER-Net observations report
  94. Integral GRB221012.88: Global MASTER-Net observations report
  95. Integral GRB221012.87: Global MASTER-Net observations report
  96. Integral GRB221012.77: Global MASTER-Net observations report
  97. Integral GRB221012.74: Global MASTER-Net observations report
  98. Integral GRB221012.72: Global MASTER-Net observations report
  99. Integral GRB221012.71: Global MASTER-Net observations report
  100. Integral GRB221012.68: Global MASTER-Net observations report

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