observation - Calculate time when star is above altitude 30°

To find the best observation time for an object, I'd like to calculate the time when it is 30° or more above the horizon. Local Sideral Time would be sufficient.

To include that in my program, I need the formula.

Example:
On June 4th, Jupiter has the coordinates
RA= 9h 19m 28.0s
Dekl= 16° 32' 0"

It rises at 10:32 and sets at 00:05.

After rise, when is it at altitude 30°, and after transit, when is it at altitude 30° again ?

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I found this formula at http://www.stjarnhimlen.se/comp/riset.html. Although it's for the sun, it seems to be what I'm looking for.

$$cos (text{LHA}) = frac{sin (text{h}) - sin (text{lat}) times sin (text{Decl})}{cos (text{lat}) times cos (text{Decl})}$$

Applied to the sample assuming a latitude of 45° I get.

Is this the correct approach?

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