Local Sidereal Time of Observation.

In summary, the astronomer at the Dominion Astrophysical Observatory is studying the K2 III star N'3148°α Arietis, located at latitude 48° 31' N in Saanich, near Victoria, B.C. The equatorial coordinates of α Arietis are right ascension=2h 07m 30s and declination of 23°29'. If the astronomer starts an observing run 3 hours before α Arietis crosses the meridian, the local sidereal time at which the observing run starts is obtained by adding -3h (since it is east of the meridian) to the right ascension of the star.
  • #1
~Sam~
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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?
 
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  • #2
Yep, that's about it. It's as simple as that. =)
 

1. What is Local Sidereal Time (LST)?

Local Sidereal Time (LST) is a measure of the rotation of the Earth with respect to the stars. It is based on the position of the vernal equinox, which is the point at which the celestial equator intersects with the ecliptic, and is used to determine the apparent positions of stars in the sky.

2. How is Local Sidereal Time calculated?

LST is calculated by multiplying the number of hours since the vernal equinox by 15 degrees, which is the amount of time it takes for the Earth to rotate 1 hour. This calculation takes into account the Earth's rotation on its axis as well as its revolution around the Sun.

3. What is the difference between Local Sidereal Time and Universal Time (UT)?

The main difference between LST and UT is that LST is based on the Earth's rotation with respect to the stars, while UT is based on the Earth's rotation with respect to the Sun. This means that LST and UT will differ by a small amount, as the Earth's rotation is not perfectly consistent.

4. How is Local Sidereal Time used in astronomy?

LST is used in astronomy to determine the position of celestial objects in the sky. By knowing the LST at a specific location and time, astronomers can accurately point their telescopes towards specific stars or other objects for observation.

5. How does Local Sidereal Time differ from Solar Time?

Local Sidereal Time and Solar Time are two different ways of measuring time based on different reference points. While LST is based on the Earth's rotation with respect to the stars, Solar Time is based on the Earth's rotation with respect to the Sun. This means that LST and Solar Time will differ by a small amount, as the Earth's rotation is not perfectly consistent.

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