Age-old locations / Astrolabes

[Ruined]

The characters in my campaign are searching for a specific location in the world, based on an event that happened several years ago. Through one NPC's help, they've been pointed in the general vicinity and they could get access to the specific date and star chart that could have been seen on that night.

I know for the most part, astrolabes were used to tell time of day and date. Is it feasible that given a date and old star charts, someone could track down a specific location?

In essence, I'm looking for a solution to finding said location without using beams of light and/or illusions as seen in Indiana Jones or the Mummy series. Any thoughts?

 

[der_kluge]

The Aztecs had a celestial calendar that tracked the location of the moon in the sky that was highly, highly accurate. In essence, the moon has a specific location as to where it appears in the night sky. Someone can provide a specific number, but the moon rotates through this pattern of where it appears in the sky once every 19,000-some odd days. That equates to 52 years or so.

So, as long as your "several years ago" falls into this kind of time period, you could have the PCs consult an ancient, ruined temple of an aztec-like culture to determine the time that such an event occurred. Now, this pyramid would have information regarding *that* location. It would be possible to translate the location of this temple to the location your PCs are seeking by basing the difference on their "general vicinity".

However, you would need modern-day latitude/longitude to account for minute differences in the appearance of the nightsky within a "general vicinity".

In other words, the night sky in boston is probably only marginally different from the night sky in New York City. Only a computer could probably really tell a difference.

Interesting plot you've got going on there, btw.

 

[jerichothebard]

Yes, although according to this page, astrolabes were the precursors to other, more sophisticated navigational instruments like the sextant.

http://www.mat.uc.pt/~helios/Mestre/Novemb00/H61iflan.htm

jtb

 

[Alchemist]

According to my planetarium software, the difference between Boston and New York is 22s latitude and 6' 54" longitude, looking at betelgeuse at the exact same time. Whether your characters can somehow resolve that difference is up to you...

What you could do, since resolving latitude is just a matter of figuring out how far off of the horizon the north star is (assuming your world has such a navigational aide), is give a different clue for the longitudinal position. Since they have a star chart, they should be able to duplicate latitude easily (polaris is 20 degrees of the horizon on the map, therefore...). Perhaps landmarks that they must sight down to draw a line through the location to get a longitudinal fix. Your landmarks don't even have to be on a N-S line, as long as the line they create pass through your location of interest.

If that dosen't make any sense (and it may not, I'm not being terribly coherent here), I'll try to draw a picture for you...

 

[Ruined]

Thanks for the replies everyone. I think I'll end up going with something along the sextant route, since they have a star chart for that point in time (the necromancers in Hollowfaust have kept such records for a long time).