Local Sidereal Time of Observation.

[~Sam~]

1. An astronomer at the Dominion Astrophysical Observatory (DAO), located at latitude
48° 31' N in Saanich, near Victoria, B.C., is studying the K2 III star N'3148°α Arietis. The equatorial coordinates of α Arietis are right ascension=2h 07 m 30s and declination of 23°29'

If the astronomer starts an observing run 3 hours before α Arietis crosses the meridian, at what local sidereal time does the observing run start?

Homework Equations

LST=HA+RA

The Attempt at a Solution

I'm wondering if I just used the equation of if there is more comprehension involved. Would I take the hour angle to be -3h (since it east of the meridian) and add it to the right ascension of the star?

 

[Matterwave]

Yep, that's about it. It's as simple as that. =)