Q:  When will M42 be highest in the sky?


  At 7 PM = 19:00 local time, its hour angle is about -2.5 hours.
That means that in 2.5 hours, it will reach the meridian, and its
highest altitude above the horizon. So,


           M42 will be highest at 9:30 PM = 21:30 local time



     Q:  The Declination of M42 is  Dec = -5 degrees.   When it crosses the
         meridian, how high above the horizon will the Orion Nebula appear?


   The latitude of the RIT Observatory is +43 degrees.  A star which has
Declination of +43 degrees will appear to pass directly overhead, at a 
maximum altitude of 90 degrees.  If M42 were on a celestial equator,
at Declination of 0 degrees, it would reach a maximum altitude 43 degrees
lower than that; in other words, it would cross the meridian at an altitude
of (90 - 43) = 47 degrees.  

    But M42 is 5 degrees further south than the celestial equator, so it
will reach a maximum altitude 5 degrees lower than that: 42 degrees above
the horizon.

    In short


          maximum altitude  =  90  -  (observer's latitude - star's Dec)