We report astrometric observations of H _ { 2 } O masers around the red supergiant VY Canis Majoris ( VY CMa ) carried out with VLBI Exploration of Radio Astrometry ( VERA ) .
Based on astrometric monitoring for 13 months , we successfully measured a trigonometric parallax of 0.88 \pm 0.08 mas , corresponding to a distance of 1.14 ^ { +0.11 } _ { -0.09 } kpc .
This is the most accurate distance to VY CMa and the first one based on an annual parallax measurement .
The luminosity of VY CMa has been overestimated due to a previously accepted distance .
With our result , we re-estimate the luminosity of VY CMa to be ( 3 \pm 0.5 ) \times 10 ^ { 5 } L _ { \odot } using the bolometric flux integrated over optical and IR wavelengths .
This improved luminosity value makes location of VY CMa on the Hertzsprung-Russel ( HR ) diagram much closer to the theoretically allowable zone ( i.e .
the left side of the Hayashi track ) than previous ones , though uncertainty in the effective temperature of the stellar surface still does not permit us to make a final conclusion .