Another thing, locations on the sky can be determined to an extravagant degree of precision, for any object bright enough to be seen at all.

Distances, OTOH, are not known for most objects, and if known, only for those bodies which are easy to measure, and/or someone is particularly interested in and took the time to determine. They are generally known only to a very low level of precision (and are frequently updated as the state of the art improves). A +/- 10% error in distance is considered excellent in astronomy. Unlike angles, which can be measured to exquisite precision, distances are often only approximate.

As a rule, nearby objects’ distances can be determined much easier and more precisely than more distant ones. For a location on the grid, distance is irrelevant. A distant galaxy’s RA and Dec are just as precise as the closest star’s.

It’s sort of like the old sailing ship days, when a navigator could use his sextant to determine latitude to within a mile, but his longitude was purely an educated guess..

Prior to some timing observations that were made in the 18th century of the transit of Venus (or maybe it was Mercury) across the sun, we had no idea what the absolute dimensions of the solar system were. We knew from geometrical reasoning the relative distances to all the planets in terms of the Astronomical Unit, but until that transit observation we had no idea how big an Astronomical Unit was.

The distances to the stars were not determined until after Bessel’s measurement of the parallax of 61 Cygni in 1838.

Hubble in the 1920s first determined the distance to an external galaxy.

As for star charts, they do not generally include distances to the stars. The maps only tell you the position in the sky of an object, its direction. However, many stars (as well as many other objects) now have determined distances and they are published in catalogues.

I do have a star atlas, The Millenium Star Atlas, that has labeled the distances of every star in the atlas less than 200 light years away, but only stars bright enough to fall within the magnitude limits of the atlas are so marked. There are many stars whose distances are known who are not labeled with a distance, but they exceed the 200 ly limit (otherwise, the map would be to cluttered to read). There are also many stars closer than 200 ly that don’t appear on the atlas at all because they’re too faint.

The Millenium Atlas has a million stars down to magnitude 11. About 10,000 stars brighter than that within 200 ly are labeled with a distance.

As a rule, though, star charts are used to identify objects at the telescope, or on photographs, or to use the charted stars as landmarks to find still fainter objects. All the information that may be known about an object usually has to be looked up in a separate catalog.

The size of the dot used to locate the star’s position gives you its brightness. Other symbols tell you if it is multiple, variable, if it has a name, or if it is peculiar, noteworthy or well-known.

I also have an atlas that color-codes the star dots by their spectral class (temperature). Additional information is often left out because it would make the map cluttered and illegible. That data, if it exists, can be found in a catalogue, or by looking up the star if you know its name or number.

Now that everything is in computerized databases available on the net, as well as downloadable big scope time exposure photogaphy of the entire sky, the Golden Age of stellar cartography is over. They are just too expensive to compile and produce, and the information is available elsewhere, cheaper and more detailed than any book can deliver.

I have a copy of what may be the very last paper atlas (2009)to be produced, it contains, among many other things, four million stars down to manitude 12, and about 70,000 galaxies. At a couple of hundred dollars I found it irresistable, but I understand the publisher went broke and has a warehouse full of them he can’t sell.

Although I seem to remember gravitational lensing requires a direct or very close to direct lineup.