Sunset Cactus Flower

We have had my large Sagurao type cactus for at least 10 years in my cactus and succulent collection. This is the first time it has flowered. The flowers are large about 15 cm across, The flowers hang down and the soft light at sunset brings out the pastel yellow and white in the flowers. These flowers only last 48 hours.  then the cactus may not flower for another 10 years