Paper Astrolabe

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Astrolabe designed for an android application – location Ottawa, Canada (developer: Robin Davies)

Some of the possible calculations with the astrolabe:
1) tell the time
2) tell what time the sun will rise the next morning
3) calculate how many hours of darkness for a given date

1) – set current calendar date on the back of the base plate with the help of the alidade
– convert to the corresponding astrological date by looking at the intersection or the alidade on the astological dates scale on the back of the base plate
– use the alidade to find the altitude of the brighest known star in the sky (outer scale of the back of the base plate)
– locate the specific star of which you have measured the altitude on the rete (front of astrolabe)
– rotate the rete to align the star with the altitude line that crosses the meridian
– the astrolabe is now set for the specific date
– rotate the rule on the rete according to the astrological date found in the first step
– follow the opposite side of the rule to determine the time of day in solar time

2) – convert the calendar date to the astrological date on the back of the base plate
– on the front of the astrolabe, rotate the rete so that the astrological date intersects the horizon
– determine the time by aligning the rule with the astrological date and follow it to the time scale

3) – convert the calendar date to the astrological date on the back of the base plate
– on the front of the astrolabe, rotate the rete so that the astrological date intersects the horizon
– align the rule to find the time (like opt 2) at each intersection of the rete on the horizon
– determine at what time the sun will rise and set and calculate remaining hours of the day to know how many hours of darkness there will be

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