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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 180905A: BOOTES-3/YA optical observations
  2. GRB 180905A: Enhanced Swift-XRT position
  3. GRB 180904A: AbAO optical upper limit
  4. GRB 180904A: Swift/UVOT Upper Limits
  5. GRB 180904A: RATIR Optical and NIR Observations
  6. GRB 180904A: Swift-BAT refined analysis
  7. Fermi GBM trigger 557852757/180905629 is not a GRB
  8. GRB 180905A: Swift detection of a burst
  9. GRB 180904A: Swift-XRT refined Analysis
  10. GRB 180904A: LT early observations
  11. GRB 180904A: SAO RAS optical observations
  12. GRB 180904A: OSN observations
  13. GRB 180904A: Enhanced Swift-XRT position
  14. GRB 180904A: NOT optical observations, candidate host galaxy
  15. GRB 180904A: Swift detection of a burst
  16. Konus-Wind observation of GRB 180828A
  17. GRB 180829A: Swift-XRT observations
  18. GRB 180828A: AstroSat CZTI detection
  19. GRB 180828A: Swift/UVOT Upper Limits
  20. GRB 180828A: RATIR Optical and NIR Observations
  21. GRB 180828A: Swift-BAT refined analysis
  22. GRB 180829A: Tiled Swift observations
  23. GRB 180829A/MAXI J0406-019: MAXI/GSC detection
  24. GRB 180828A: Swift-XRT refined Analysis
  25. GRB 180828A / Swift J1754.9-2548: Enhanced Swift-XRT position
  26. GRB 180828A: Fermi GBM observation
  27. GRB 180828A: Swift detection of a GRB or possible Galactic Transient Swift J1754.9-2548
  28. GRB 180728A: classification of the associated SN 2018fip
  29. Konus-Wind observation of GRB 180824A
  30. Fermi GBM trigger 557014342/180826925 is not a GRB
  31. Fermi GBM trigger 557008382/180826856 is not a GRB
  32. GRB 180818B: TSHAO optical upper limit
  33. GRB 180824A: MASTER inspection IPN short GRB error box
  34. GRB 180823A, Swift-BAT refined analysis
  35. IPN Triangulation of GRB 180824A (short)
  36. GRB 180823A: Swift/UVOT Upper Limits
  37. GRB 180823A: RATIR Optical and NIR Observations
  38. GRB 180823A: Swift-XRT refined Analysis
  39. GRB 180823A: Enhanced Swift-XRT position
  40. GRB 180823A: Swift detection of a burst
  41. GRB 180821A: VLT observations
  42. GRB 180821A: Swift/UVOT Upper Limits
  43. GRB 180821A: Swift-BAT refined analysis
  44. GRB 180821A: iTelescope counterpart is not the afterglow
  45. GRB 180821A: Swift-XRT refined Analysis
  46. GRB 180821A: LCO Siding Springs observations
  47. GRB 180821A: Enhanced Swift-XRT position
  48. GRB 180818B: 1.5m OSN optical afterglow candidate
  49. GRB 180821A: iTelescope optical afterglow detection
  50. GRB 180821A: BOOTES-3/YA optical observations
  51. GRB 180821A: Swift detection of a burst
  52. GRB180806A: confirmation of the X-ray afterglow
  53. GRB 180818B: Swift-XRT refined Analysis
  54. GRB 180818B: Swift-BAT refined analysis
  55. GRB 180818A: Swift-BAT refined analysis
  56. GRB 180818B: Fermi GBM observations
  57. GRB 180818B: Swift/UVOT Upper Limits
  58. GRB 180818B: Enhanced Swift-XRT position
  59. GRB 180818A: Swift/UVOT Upper Limits
  60. GRB 180818B: Swift detection of a burst
  61. GRB 180818A: Swift-XRT refined Analysis
  62. GRB 180818A: Enhanced Swift-XRT position
  63. GRB 180818A: Swift detection of a burst
  64. Swift Trigger 853790 is probably not an astrophysical source
  65. GRB 180809B: AstroSat CZTI detection
  66. GRB 180728A: MASTER early polarization and 19 days monitoring
  67. GRB 180728A: discovery of the associated supernova
  68. GRB 180809A: further Swift/XRT observations
  69. Correction: Chandra X-ray observations of GW170817 at 1 year post-merger: increasingly rapid fading
  70. LIGO/Virgo GW170817: A steep decline in the radio light curve and prediction for the X-rays
  71. GRB 180812A: Swift/UVOT Detection
  72. Chandra X-ray observations of GW170817 at 1 year post-merger: increasingly rapid fading
  73. GRB 180812A: Swift-BAT refined analysis
  74. GRB 180812A: Fermi GBM detection
  75. GRB 180812A: Swift-XRT refined Analysis
  76. GRB 180809B: ePESSTO NTT NIR observations
  77. GRB 180812A: COATLI Detection and Light Curve
  78. GRB 180812A: Enhanced Swift-XRT position
  79. GRB 180812A: BOOTES-5/JGT optical afterglow detection
  80. GRB 180812A: Swift detection of a burst
  81. Konus-Wind observation of GRB 180809B
  82. GRB180809B TUG T60 observations
  83. MASTER: OT detection during two Fermi GBM triggers (555263883 and 555263883) error boxes inspection in 22.5 mag SDSS galaxy direction
  84. GRB 180809B: Swift-XRT refined Analysis
  85. GRB 180809B: CrAO optical observations
  86. GRB 180809B, Swift-BAT refined analysis
  87. GRB 180806A: AstroSat CZTI detection
  88. Swift Trigger 852625: Swift/BAT/XRT/UVOT observations
  89. GRB 180809B: Swift/UVOT Detection
  90. Konus-Wind observation of GRB 180806A
  91. GRB 180809A: Fermi GBM observation
  92. GRB 180809A: CALET Gamma-Ray Burst Monitor detection
  93. GRB 180809B: CALET Gamma-Ray Burst Monitor detection
  94. Swift Trigger 852625: a possible GRB
  95. GRB 180809B: VLT optical upper limits
  96. GRB180809B: MASTER Triple Independent Automatic OT Detection
  97. GRB 180809B: LCO Sutherland observations
  98. GRB 180809B: GROND Detection of the NIR Afterglow
  99. GRB 180809B: RATIR Optical Observations and Confirmation of Rapid Fading
  100. GRB180809B: MASTER OT observation

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