Worksheet for correcting reddening and extinction


1. Measure observed apparent magnitudes of star in two filters; here, B and V

             B  =  _________
             V  =  _________


2. Calculate observed color (B-V)

            (B-V) = __________


3. Observe spectral type of star

             spectral type =  _________


4. Use spectral type to determine the intrinsic color of the star (B-V)0

             (B-V)0 =  _________


5. Compute the color excess E(B-V)

            E(B-V)  =  (B-V)  -  (B-V)0  =  ________


6. Using the ratio of selective to total extinction (easy to look
      up in reference sites or textbooks) for each filter,
      calculate the extinction in each measurement.


           AB  =  4.1 * E(B-V)  =  __________
           AV  =  3.1 * E(B-V)  =  __________


7. Correct the observed apparent magnitudes by subtracting the extinction
      from each one.

  
           corrected B0  =  B - AB =  _________
           corrected V0  =  V - AV =  _________