1. The problem statement, all variables and given/known data Out to what distance in parsecs can we find the distances of stars to 10% accuracy or better; i.e., at what distance would the 1 mas accuracy of the measurements result in a 10% uncertainty in the distance? (HINT: To reasonable accuracy, the percentage uncertainty in the inverse of a quantity equals the percentage uncertainty in the quantity itself.) 2. Relevant equations Tan(θ)= opp/adj 3. The attempt at a solution My teacher tells me that this is all the information I need, this question mentioned the Hipparcos catalogue, but I was told I didn't need it. Any ideas? I know how to calculate the distance of a celestial object using parallactic angle..but how are you suppose to know the uncertainity?