What night of the week did Bonanza originally air when it first aired

1. 1- 1 12 Sep 59 A Rose for Lotta
http://epguides.com/Bonanza/

September 12, 1959 was a Saturday
http://www.timeanddate.com/calendar/?year=1959&country=1

"Everybody knows it was on Sunday night," was my first thought. On checking, I found it was shown on Saturday night for the first two seasons. -- "Bonanza, the first Western televised in color, premiered on a Saturday night in the fall of 1959. ... Two years after its debut, Bonanza moved to Sunday night and its popularity soared." -- museum.tv/archives/etv/B/htmlB/bonanza/bonanza.htm no longer exists

The premiere was on September 12, 1959, and the final episode broadcast on January 16, 1973.[2] In its initial season, Bonanza aired on Saturday evenings and placed at number 45 in the Nielsen ratings. During its second season, the series moved up to number 17. Bonanza was moved to Sundays at 9:00 PM Eastern Time at the start of its third season. In that time slot, the ratings soared and the series become second only to Wagon Train as the most popular program on American prime time television. It remained in the top ten of the ratings until its twelfth season and ranked at number one in its sixth, seventh, and eighth seasons. Bonanza also became a worldwide success as it was broadcast in nearly 50 countries, including Canada, Brazil, Yugoslavia, the United Kingdom, France, Italy, Switzerland, Saudi Arabia, Thailand, Australia, and Japan.

https://en.wikipedia.org/wiki/List_of_Bonanza_episodes