LST Clock is an application that displays the current Local Sidereal Time at several observatories. You can also enter your own longitude (west of greenwich is positive in this application), to get the Sidereal time in other locations. Sidereal time is a time system which measures the rotational orientation of the Earth relative to the stars rather than the Sun. Effectively the Sidereal day is about 4 minutes less than the Solar day. Why four minutes? Because as our planet rotates about its axis, it also revolves around the Sun. During one day the Earth manages to move about one degree in its orbit around the Sun. This means that the Earth must revolve one additional degree (or 361 degrees) for the Sun to appear to return to its original position. This takes 24 hours. However 360 degrees of rotation only takes about 23 hours and 56 minutes, or one Sidereal day.
Why is Sidereal time important? Mostly we can ignore the subtleties of Sidereal time and stick with Solar time, however in those cases where you actually want to know where the stars might be at any given time, you will want to know the Local Sidereal Time. The positions of astronomical objects are recorded in Right Ascension (RA) and Declination (Dec). Declination is similar to Latitudes on the Eath, and runs from 90 degrees south (-90) which would be above the south pole of the Earth to 90 degrees north (+90) which is above the north pole of the Earth. 0 degrees declination would be the position of any star or object directly above the equator. Right Ascension is similar to Longitude on the Earth, however Right Ascensions are fixed in the sky and the Earth rotates under these Right Ascension lines. We measure Right Ascension in terms of hours, minutes, and seconds. 1 hour of Right Ascension corresponds to 15 degrees on the sky at a Declination of 0. The Right Ascension above any point on the Earth is constantly changing as the Earth rotates. So 1 hour Right Ascension may be above you now, but later 2 hours Right Ascention will be above you. The Local Sidearal Time actually indicates what the Right Ascension is in the sky directly overhead. So at 2:15 LST the Right Ascension 2hours and 15 minutes is directly overhead. Armed with a Sidereal Clock and an astronomical atlas you can find just about anything in the sky. Binoculars or a telescope might be helpful.
Click the link below to run a Sidereal Clock.