Q:  What is the age of stars in the cluster NGC 104?

            The color of the turnoff point in the 
            cluster is about (B-V) = 0.5.  The models
            with the same turnoff color appear to
            be around 1-3 Gyr old.


   Q:  What is the distance modulus (m - M) for stars in
       the cluster NGC 104?

            The apparent V magnitude of the turnoff point
            in the cluster is about m = 17.  
 
            The absolute V magnitude of the turnoff point
            in models of the same age is about M = 2.5.

            The distance modulus is thus 

                (m - M)  =  17 - 2.5  =  14.5


   Q:  What is the distance to the cluster NGC 104?

            We can use the formula


                (m - M)  =  5 log d  -  5

                            (m - M) + 5       14.5 - 5
               log d     =  -----------   =   --------  =  3.9
                                5                5


                              3.9 
                    d    =  10       =   7900 pc