Slowly flashing stationary whitish light observed by 75 witnesses observed during a star party over Mcdonald Observatory.As I was volunteering at a star party for a half hour every group asked me to leave the 16" Meade and witness a immobile flashing light in the sky. Because of my duties at the telescope I did not leave until it became clear that this was a very unusual event. I finally left the telescope and walked to the edge of the dome from where I could see the slowly flashing light in the sky through the dome opening slot. The light appeared to be about a mile away. Everyone in my group of about 75 people saw the slowly flashing stationary light. For two hours everyone saw it. When the star party ended I told the supervisor about it. Strangely no other group but mine reported seeing the whitish flashing light. The supervisor good naturedly said , "you saw a UFO".((NUFORC Note: Witness indicates that date is approximate. PD))