Gemara:

Kiddushin 

Halacha:

Kriyat HaTorah,  Rosh Hashana,  Tefillah,  Yom Kippur 

Collections: R' Grunstein Turning your back to Aron-Kodesh

References: Kiddushin: 33B  

Description

One MUST stand ONLY for the Torah on the go/for a Torah that is Mobile, but not when its stantionary. Thus, no obligitory to stand when opening the Ark WITHOUT taking out the Torahs, as well as for someone sitting with the Torah (during the הפטרה) as well as when saying a א-ל מלא רחמים at the Bima with the Torah in one's hand