A compass is tricky, a high end compass should have an adjustment to correct for magnetic to geodetic azimuths.
Basically it simply rotates the face of the compass so the numbers align with geodetic north instead of magnetic north, when the needle points north the compass reads 12 degrees
I would always check my correction to a known line direction. Not sure what street or line you can check it against but it's mostly getting the correction and making sure you rotate the face the correct direction, then 54 degrees on your compass will point along the great circle line you want. Be careful that it's not being magnetically influenced by a local attraction. That's easy as you can point it then walk along the line and be sure it keeps pointing that same direction.?ÿ
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A compass inside a building would not be sufficiently reliable.
If it were my job to know.?ÿ
I'd want to know the source of the coordinates.?ÿ
I could take my GPS gear to the particular spot in Jerusalem, and store this point. Then, as I moved about the world, I could "stake out" Jerusalem. Eventually, I'd place a mark on the ground, and then another mark, so that all 3 points, we're in a straight line. Then, I could use a magnetic compass to determine precisely what the declination was.?ÿ
This could include the vertical component as well.?ÿ
N
You could set your total station up, and hit "turn to point" and it would!
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Probably overkill, as explained in the article I posted.?ÿ
IMO, the first answer to your question from bill93 is all you need to know to look in the direction you want and can be made a little easier by a couple of the others, but don't let them spin you around too much.?ÿ My first thought about bill's answer was also that if you have an iPhone, you can go to Settings, scroll down to Compass, make sure it's set to True North and it automatically compensates for your local magnetic declination.?ÿ And by default, it displays in north azimuth.?ÿ So, one setting and you can point right at it; to the nearest degree anyway.
Quick correction to this:?ÿ On the site you linked that you got your azimuth from (cool site, btw), they say "Compass from A to B" for the azimuth, but the formula they list beneath it is actually a geodetic formula for calculating azimuth, ie having no magnetic influence that a physical compass would have.?ÿ Bad terminology there for a survey tech.?ÿ So I checked the geodetic ("true") azimuth from an NGS site calculator and the Az given is the same given in your sites "compass" reading.?ÿ No magnetic adjustment necessary.?ÿ Set iPhone to true north and turn to the 54 degrees.
@mightymoe mine read about the same with iphone on 'magnetic north'.?ÿ Only advantage I might see is being able to interpolate between degrees on the compass where the iphone stock compass app only reads to a degree.