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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 221016A: Swift-BAT refined analysis
  2. GRB 221016A: Swift/UVOT Detection
  3. GRB 221016A: Swift-XRT refined Analysis
  4. Konus-Wind detection of GRB 221016A
  5. GRB 221016A: Fermi GBM observation
  6. GRB 220926B: Detection by GRBAlpha
  7. GRB 221009A: A type I BdHN of exceptional energetics
  8. MAXI GRB221017.24: Global MASTER-Net observations report
  9. GRB 221016A: z-band upper limit, possible afterglow brightening
  10. GRB 221017A: MAXI/GSC detection
  11. GRB 221016A: Enhanced Swift-XRT position
  12. GRB 221016A: LCOGT Optical Afterglow Detection
  13. GRB 221016A: Swift detection of a burst
  14. GRB 221016A: Fermi GBM Final Real-time Localization
  15. Swift GRB221016.99: Global MASTER-Net observations report
  16. GRB 221009A: Faulkes Telescope North continued optical afterglow follow-up
  17. Konus-Wind detection of a short burst coincident with a bright radio burst from SGR 1935+2154
  18. GRB 221009A: continued Assy optical afterglow observations, possible SN evidence
  19. Konus-Wind observation of the recent SGR 1935+2154 activity
  20. GRB 221009A: LEIA X-ray Afterglow Detection
  21. GRB 221009A: ATCA radio spectrum
  22. GRB 221009A: VLT spectroscopic detection of the host galaxy
  23. Fermi Gamma-ray Burst Monitor detections of SGR 1935+2154
  24. GRB 221009A: ATCA detection
  25. GRB 221009A: Armchair Energetics
  26. GRB 221009A: ALMA and ACA detections
  27. GRB 221009A: Fermi LAT data rate effects due to extremely high flux
  28. GRB 221009A: Large Binocular Telescope Observatory optical afterglow detection
  29. GRB 221009A: Pan-STARRS optical photometry
  30. GRB 221009A: VLA detection
  31. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  32. GRB 221009A: continued REM optical/NIR observations and evidence for an achromatic steepening in the afterglow light curve
  33. GRB 221009A: IXPE preliminary upper limits of X-ray polarization
  34. GRB 221009A: OHP optical observations
  35. GRB221009A: RTT-150 optical observations
  36. GRB 221009A: HEBS detection
  37. GRB 221009A: Gemini-South Infrared Afterglow Detection
  38. GRB221009A: Gemini-South Optical Afterglow Detection
  39. GRB 221009A: a 397.7 GeV photon observed by Fermi-LAT at 0.4 day after the GBM trigger
  40. GRB 221014A: Fermi GBM Final Real-time Localization
  41. GRB 221009A: Gamma-ray Detection by SIRI-2
  42. GRB221009A: Ionospheric disturbance observed in India
  43. GRB221009A: Detection as sudden ionospheric disturbances (SID)
  44. GRB221009A: RTT-150 optical observations
  45. MAXI GRB 221006A: Redshifts of the possible host galaxies
  46. GRB 221009A: search for neutrinos with KM3NeT
  47. GRB 221009A: MeerKAT detection
  48. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  49. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  50. Fermi Gamma-ray Burst Monitor continues to detect SGR 1935+2154
  51. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  52. Fermi trigger No 687345829: Global MASTER-Net observations report
  53. Fermi trigger No 687344475: Global MASTER-Net observations report
  54. Fermi trigger No 687340841: Global MASTER-Net observations report
  55. Fermi trigger No 687337536: Global MASTER-Net observations report
  56. GRB 221006A: Swift-XRT afterglow detection
  57. GRB 221009A: MITSuME Okayama optical observation
  58. GRB 221009A: Sayan observatory 1.6-m telescope observations
  59. Fermi trigger No 687281393: Global MASTER-Net observations report
  60. GRB 221009A: GMG observation
  61. GRB 221013B: Fermi GBM Final Real-time Localization
  62. Integral GRB221013.04: Global MASTER-Net observations report
  63. GRB 221013A: Fermi GBM Final Real-time Localization
  64. Integral GRB221013.00: Global MASTER-Net observations report
  65. Integral GRB221012.99: Global MASTER-Net observations report
  66. Integral GRB221012.94: Global MASTER-Net observations report
  67. Integral GRB221012.91: Global MASTER-Net observations report
  68. Integral GRB221012.88: Global MASTER-Net observations report
  69. Integral GRB221012.87: Global MASTER-Net observations report
  70. Integral GRB221012.77: Global MASTER-Net observations report
  71. Integral GRB221012.74: Global MASTER-Net observations report
  72. Integral GRB221012.72: Global MASTER-Net observations report
  73. Integral GRB221012.71: Global MASTER-Net observations report
  74. Integral GRB221012.68: Global MASTER-Net observations report
  75. Integral GRB221012.68: Global MASTER-Net observations report
  76. Integral GRB221012.98: Global MASTER-Net observations report
  77. Afterglow limits of GRB 221006A from OHP
  78. GRB221009A: optical afterglow measurements from Konkoly Observatory
  79. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  80. GRB 221009A/Swift J1913.1+1946: SMA observations
  81. INTEGRAL shows increasing activity in SGR J1935+2154
  82. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  83. Integral GRB221012.63: Global MASTER-Net observations report
  84. Integral GRB221012.61: Global MASTER-Net observations report
  85. Integral GRB221012.60: Global MASTER-Net observations report
  86. Integral GRB221012.53: Global MASTER-Net observations report
  87. GRB 221009A/Swift J1913.1+1946: eMERLIN observations
  88. Fermi trigger No 687205006: Global MASTER-Net observations report
  89. INTEGRAL detection of a burst from SGR J1935+2154
  90. GRB 220829A: Detection by GRBAlpha
  91. GRB 220826B: Detection by GRBAlpha
  92. GRB 221009A: NuSTAR Detection
  93. GRB 221009A: NICER follow-up observations
  94. GRB 221009A: LCOGT Optical Afterglow Detection
  95. GRB 221009A: COATLI Detection of the Afterglow
  96. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  97. GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
  98. Fermi trigger No 687190301: Global MASTER-Net observations report
  99. GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
  100. Fermi Gamma-ray Burst Monitor trigger 221011452/687178284 is not a GRB

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