When is the next 13.00 Local Sidereal Time for a UK observer?

In summary, the next "13.00 Local Sidereal Time" for a UK observer is at 10:06pm and the star "Phecda" and the galaxy "M109" will be almost directly overhead. The centre of the Milky Way is tilted 30 degrees from the horizon and located to the southeast, 20 degrees below the horizon. There are no named stars within 10 degrees of the nadir. Moving north or south from the UK, there may be different stars near the nadir and zenith, but the centre of our galaxy's cluster cannot be pinpointed on the sky.
  • #1
Ulysees
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When is the next "13.00 Local Sidereal Time" for a UK observer?

Anyone with software or equations to work that out?
 
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  • #2
You can work it out yourself fairly easily. When the Sun passes through your local meridian (i.e. - noon), your local sidereal time is whatever right ascension the Sun is at. Right now, the Sun is at ~2h54m. To get to 13h00m, you therefore need to wait 13:00-2:54=10:06. That would mean that 13h00m passes overhead at 12:00pm + 10:06 = 10:06pm.

Though that presumes that your local noon, when the Sun is in the middle of the sky, is in fact 12:00pm! Depending on where you are in the timezone this may be incorrect, and you would have to add (or subtract) whatever is the difference.
 
  • #3
Thanks.

What star is directly above an observer at 13.00 LST? (Observer at Britain's latitude and longitude).

Is the centre of the galaxy directly above?

Is the centre of the galaxy in the opposite direction perhaps? (Directly below the feet of the observer).

Is there some important star directly above (or directly below)?
 
  • #4
A google for "sidereal time calculator" yields lots of hits. Here's the first: http://tycho.usno.navy.mil/sidereal.html

According to Starry Night, the star "Phecda" and the galaxy "M109" are almost directly overhead at that time (given in the previous post) and the Milky Way is tilted roughly 30 degrees from the horizon from north to south (imagine a hula hoop around your waist, tilted up 30 degrees). The center of the Mikly Way is to the southeast, 20 degrees below the horizon. There is no named star within 10 degrees of the nadir.
 
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  • #5
That's impressive. Thanks Russ.

Any named star within 1 hour (+/-15 degrees) from the nadir?

What if the observer is north or south of the UK, all the way to the equator or the north pole? Anything significant near the nadir or zenith for this observer?
 
  • #6
Do we know where the centre of the cluster that our galaxy belongs to, resides on the sky?
 

1. What is Local Sidereal Time (LST)?

Local Sidereal Time is a measure of the Earth's rotation relative to the stars. It is based on the position of the vernal equinox and is used to determine the local time of a specific location on Earth.

2. How is Local Sidereal Time calculated?

Local Sidereal Time is calculated by converting the current Universal Time (UT) to the local time zone and then adding the observer's longitude in degrees. This gives the Greenwich Sidereal Time (GST), which is then adjusted for the Earth's rotation rate and the vernal equinox.

3. Why is Local Sidereal Time important for astronomers?

Local Sidereal Time is important for astronomers because it is directly related to the position of the stars in the sky. It is used to determine when a specific star or constellation will be visible in the night sky for a given location.

4. How do I convert LST to my local time zone?

To convert LST to your local time zone, you will first need to know your longitude and the current Universal Time (UT). Once you have this information, you can use a conversion chart or online calculator to determine the corresponding local time.

5. When is the next 13.00 LST for a UK observer?

The next 13.00 LST for a UK observer will vary depending on the current Universal Time (UT) and the longitude of the observer's location. It is recommended to use an online calculator or astronomical software to determine the exact time for a specific date and location.

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